Buller (2014) The Impacts of Climate Change on Geological Processes

April 2014
The Impacts of Climate Change on
Geological Processes
Stephanie Marie Buller
Submitted to the Department of Geography, Environment and Disaster Management of
Coventry University towards BSc Geography and Natural Hazards

Buller, (2014) Climate Change and Geological Processes
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The Impacts of Climate Change on Geological Processes
Abstract;
Future climatic change as a result of anthropogenic climate warming may potentially promote the
occurrence of geological phenomena. This paper critically reviews and evaluates existing literature
which seeks to determine causal links between climate change and increased geological activity. This
paper builds upon the work of McGuire (2010) in order to develop an unbiased evaluation of the
extent to which contemporary climate change may alter the frequency of geological events. Patterns
of climatic change associated with volcanic, seismic and submarine landslide occurrences during the
late Quaternary are discussed, followed by a critical review of the mechanism by which climate
change may alter geological processes. This paper further identifies aleatory, epistemic and
ontological uncertainties which exist and impede our understanding of current climate science and
geological system responses. The extent to which contemporary climate change may trigger a
geological response remains uncertain and controversial, as assuming uniformitarianism, it is likely
that the frequency of volcanic, seismic and submarine landslide events may increase in response to
climate changes. In order for the true extent to be accurately determined, uncertainties must be
reduced, for which areas of further study have been identified and recommended.
Keywords: Climate Change, Quaternary, Holocene, Deglaciation, Sea Level Rise, Post Glacial
Rebound, Volcanoes, Earthquakes, Submarine Mass Failures

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Declaration and Acknowledgments
Declaration
I hereby declare that this project is entirely my own work and where I have used the work of others
it has been referenced correctly. I can also confirm that the project has been completed in
compliance with the University ethics policy and that the information that was supplied with the
original ethics document handed in with the project proposal corresponds with the work conducted
for the project.
Acknowledgements
The Author would like to acknowledge and thank Dr. Jason Jordan for his unwavering guidance,
support and kindness over the years. But most importantly I thank you for showing me my research
interest, and for which I shall always be grateful. Without you this would not have been possible and
I would not be as determined to pursue every opportunity that now lay ahead of me as a result, you
have given me the confidence to believe in myself and follow my dreams.
The author would further like to thank family for their support through the challenges I have faced
over the years. In particular Simon, you have been my rock and my strength throughout this last
year, and I would truly have not made it to this point without you. I am truly blessed to have such a
wonderful person in my life.

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Table of Contents
Chapter 1: Paper Overview.....................................................................................................................6
Section 1: Introduction .......................................................................................................................6
1.2: Aims, Objectives and Methodology.........................................................................................7
Chapter 2: Climate Change .....................................................................................................................8
Section 1: Climate Forcing ..................................................................................................................8
1.1: Sub-Milankovitch Cycles (D-O/Heinrich Events)....................................................................10
1.2: Volcanic Forcing.....................................................................................................................10
1.3: Anthropogenic Forcing...........................................................................................................11
Section 2: Contemporary and Future Climate Change .....................................................................14
2.1: Contemporary Climate Change and Implications for Geological Activity..............................17
Section 3: Climate Change Uncertainty ............................................................................................18
Chapter 3: The Quaternary...................................................................................................................22
Section 1: Glacial/Interglacial Cycles ................................................................................................22
Section 2: Abrupt Climatic Change during the Quaternary ..............................................................23
2.1: The Younger Dryas.................................................................................................................24
2.2: The 8.2Ka Cold Event .............................................................................................................27
Chapter 4: The Impact of Climate Change on Volcanoes .....................................................................29
Section 1: Volcanism and Past Climatic Change ...............................................................................29
Section 2: Effects of Glacial loading and Deglacial Unloading on Volcanic Processes......................30
Section 3: Effects of Sea Level Rise on Volcanic Processes...............................................................32
Section 4: Contemporary Climate Change and Volcanic Activity .....................................................36
Chapter 5: The Impact of Climate Change on Seismicity......................................................................37
Section 1: Seismicity and Past Climatic Changes ..............................................................................37
Section 2: Post Glacial Rebound and Seismic Frequency..................................................................39
Section 3: Eustatic Loading and Seismic Frequency .........................................................................45
Section 4: Contemporary Climate Change and Seismic Activity.......................................................49
Chapter 6: The Impact of Climate Change on Submarine Failures.......................................................49
Section 1: Submarine Failures...........................................................................................................50
Section 2: Submarine Failures and Past Climatic Changes ...............................................................53
Section 3: Rates of Sedimentation and Slope Stability.....................................................................54
Section 4: The Holocene Storegga Slide ...........................................................................................55
4.1: The 8.2Ka Event, LAO and Storegga.......................................................................................55
Section 5: Sea Level Rise and Submarine Failures ............................................................................57

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5.2: Eustatic Induced Seismicity as a triggering mechanism ........................................................58
Section 6: Contemporary Climate Change and Submarine Failures.................................................60
Chapter 7: Final Discussion and Concluding Remarks ..........................................................................60
Section 1: Final Discussion................................................................................................................60
Section 2: Concluding Remarks.........................................................................................................62
References ............................................................................................................................................64

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List of Figures Found
Figure 1: Solar and cosmic factors that influence climate. ...................................................................8
Figure 2: Orbital variations, solar energy changes and resulting glacial cycles,.....................................9
Figure 3: Effects of stratospheric aerosols on the atmosphere............................................................10
Figure 4: The natural greenhouse gas effect. .......................................................................................12
Figure 5: Northern Hemisphere Temperature changes over the last millennia...................................13
Figure 6a and b): Northern and southern hemisphere temperatures over last 2 millennia................14
Figure 7: Modelling results and recorded observations for the last 100years.....................................15
Figure 8: Climate modelled scenarios...................................................................................................16
Figure 9: The Earth’s Climatic System..................................................................................................19
Figure 10: The uncertainty explosion ...................................................................................................19
Figure 11: The cascade of uncertainties ..............................................................................................20
Figure 12: Climate Modelling uncertainties..........................................................................................21
Figure 13: Ocean temperature oscillations...........................................................................................22
Figure 14: An Overview of Quaternary Climatic Changes.....................................................................23
Figure 15: Lake Agassiz and Laurentide ice sheet.................................................................................25
Figure 16: Lake Agassiz re-routing. .......................................................................................................25
Figure 17: Sea level rise and tephra emplacing events.........................................................................34
Figure 18: Melting response to change in sea level..............................................................................35
Figure 19: Effects of glacial loading on the crust..................................................................................40
Figure 20: Effects of unloading and Glacio-Isostatic Rebound .............................................................40
Figure 21: Correlation between glacial unloading and increased slip rates.........................................41
Figure 22: The Wasatch Fault ...............................................................................................................42
Figure 23: The Teton fault.....................................................................................................................42
Figure 24: Elevated slip rates along the Wasatch Fault during the LGM..............................................43
Figure 25: Effects of ice loading on the Teton fault..............................................................................44
Figure 26: Global Relative Sea Level rise following the LGM 20Kya to present ...................................45
Figure 27: Rapid Global Eustatic Sea Level Rise during the Holocene period 10Kya to present..........46
Figure 28: Relative sea level rise since the LGM...................................................................................47
Figure 29: The 4 main types of submarine instability...........................................................................50
Figure 30: The causes of submarine landslides ....................................................................................51
Figure 31: The factors and processes responsible for initiating Submarine Slope Failures .................51
Figure 32: Locations of known Submarine Mass Failures.....................................................................52
Figure 33: Submarine Landslide Regions ..............................................................................................53
Figure 34: The LAO discharge, Holocene Storegga slide and Storegga slide tsunami..........................56
Figure 35: Meltwater pulses, sea level rise and submarine landslides.................................................57
List of Tables Found
Table 1: Post Glacial Faults documented in Finland, Norway and Sweden..........................................38
Table 2: Norwegian post glacial faults considered to be almost certainly neotectonic.......................38

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Chapter 1: Paper Overview
Section 1: Introduction
As global population rises, the population interface becomes increasingly vulnerable to the risk from
natural disaster through urban expansion and resource disparity; furthermore the threat of climate
change is gradually becoming recognised around the world.
Climate change is referred to as the change in regional climate resulting from alterations in
temperature and/or precipitation. This is often the result of larger complex system interactions
between the global climate system, and external forces such as Croll-Milankovitch cycles, Oceanic
Decadal Oscillations, volcanic aerosols and solar irradiance.
The IPCC, confirmed in the AR5 Report and summary for policy makers that the world’s climate is
changing, and the threat from climate change is now irrefutable (IPCC, 2013). The IPCC confirms we
are entering into a periods of warmer climate, following the last glacial maximum, this is a known
natural cycle referred to as an interglacial. However this natural process has been exacerbated by
anthropogenic activity, resulting in accelerated warming.
Anthropogenic climate change is a change in the Earth’s climate as a result of human activities and
this includes the combustion of fossil fuels and the release of aerosols into the atmosphere.
Resulting in changes to atmospheric composition, that amplifies natural green-house gas (GHG)
effects, this causes global temperature increases as more solar-radiation becomes trapped by the
GHG.
Anthropogenic climate change is currently of global concern, rising land and sea surface
temperatures, may lead to rapid climatic shifts in precipitation levels, increasing the risk of flood,
drought and famine. Temperature increases will also enhance deglaciation, melting of land-based
glaciers, ice caps and ice sheets and will result in global sea level rise.

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The topic of this paper is concerned with the consequences of climate change upon geological
activity. This paper seeks to investigate the methods by which climate has the capacity to alter
geological processes such as volcanic eruptions, seismicity and submarine failures, through evidence
of past climate shifts and geological responses as well as theoretical and empirical understanding of
the process and mechanisms which can be altered and the method by which they are influenced by
climate change processes.
1.2: Aims, Objectives and Methodology
 The primary aim of this paper is to give an in-depth understanding and critical analysis of
existing literature that seeks to determine a link between climate change processes and
potential geological responses. To achieve this aim the objective is to collect, collate and
critically review theoretical and empirical studies regarding the topic of this paper.
 The secondary aim of this paper is to determine possible future geological responses from
anthropogenic climate change. This aim will be fulfilled through the discussion and
evaluation of the mechanism by which climate change may alter geological events, seeking
to unite this with the current understanding of anticipated climate change impacts, with
previous examples of geological responses to climate change during the late Quaternary.
 The final aim of this paper is to identify uncertainties which surround the current
understanding of the topics reviewed in this paper. This will be achieved by identifying and
recommending areas for further study in order to reduce uncertainties and increase
understanding regarding future geological responses to climate change.
This project has no direct primary fieldwork data collection, due to limitations which make primary
collection unsuitable. Therefore, secondary data will be utilised, collected from a range of
academically recognised sources such as journals, books and reports from key field-leading
researchers and institutional organisations. However it is worth noting limitations associated with
this method, such as access to material, opinion biases, currency, and relevancy. The literature will
be reviewed and critically assessed in order to determine the links that exist between geological
processes and climate change processes.

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Chapter 2: Climate Change
This paper will be focusing on known geological events associated with times of abrupt or rapid
climate change, such as the Quaternary. Therefore, this chapter aims to explore mechanisms of both
natural and anthropogenic climate change, as well as discussing future climate change scenarios and
evaluating uncertainties, with regards to future climate predictions in the context of geological
hazards.
Section 1: Climate Forcing
Wanner et al., (2008) state that natural climatic forcing can occur through orbital, solar, eruption,
land cover and GHG variations. Furthermore Wanner et al., (2008) cite that predominant climate
change during the Holocene is a result of forcing through orbital, solar and volcanic variations. A
simplified diagram of solar and cosmic variations is shown in figure 1.
Figure 1: Shows solar and cosmic factors that influence climate. Fluctuations in UV variations and solar wind are natural
external triggers to climate change by altering the Stratosphere and Troposphere; Van Geel et al., (1999).

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Orbital forcing refers to the quantity of solar radiation that reaches the Earth’s upper atmosphere as
a result of solar forcing and astronomical forcing (Berger et al., 2013) which includes axial
orientation and positioning relative to the sun. Astronomical theory is commonly referred to as
Croll-Milankovitch cycles where changes to orbital eccentricity occur at 400,000 and 100,000yr
intervals, variations in axial tilt occur at 40,000yr intervals and changes in axial precission occur at
20,000yrs (Wanner et al., 2008; Bennet, 1990; Imbrie and Imbrie, 1979, Dawson, 1992; Raymo and
Nisancioglu, 2003).
Solar forcing is the result of changes in the energy output from the sun (Wanner et al., 2008) and
this refers to sunspot cycles, a change in total solar irradiance, from minima to maxima, in an 11year
Schwabe Cycle (Lean et al., 1995; Wanner et al., 2008). However as noted by Wanner et al., (2008)
exact sun cycles have as yet been poorly identified and constrained, but are thought to have played
an important role in Quaternary climate forcing (Pekarek, 2000; Beer et al., 2000; Van Geel et al.,
1999). Figure 2 shows the effects of Precession, Obliquity, Eccentricity, and Solar Forcing on Glacial-
Interglacial cycles.
Figure 2: Graph depicting orbital variations, solar energy changes and resulting glacial cycles, as a consequence of
Milankovitch cycles, demonstrating solar and orbital forcing of climate on 100kyr intervals; Adapted from Quinn et al.,
(1991) and Lisiecki and Raymo (2005).

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1.1: Sub-Milankovitch Cycles (D-O/Heinrich Events)
Dansgaard-Oeschger (D-O) events/cycles are abrupt periods of climate oscillation that occurred
approximately 25 times during the Last Glacial Period based on Greenland Ice-cores (Bond et al.,
1999; 1993; 1992; Bond and Lotti, 1995). Heinrich events describe an influx of icebergs being
released into the north Atlantic, which then melt and release large volumes of freshwater, with six
distinct events having been recorded during the last glacial maximum period and transition into the
Holocene (Bond et al., 1999; 1993; 1992; Bond and Lotti, 1995; Broecker, 1992; Heinrich, 1988;
Maslin et al., 2001). Conclusions have been that the two events are connected, that the large
freshwater influx from the iceberg rafting is responsible for the changes in the thermohaline
circulation which in turn may cause the Dansgaard-Oeschger cycles (Rabassa, 2013; Labeyrie, 2007).
However as noted by many authors the exact relationship between D-O and Heinrich events with
the climate is yet to be fully understood.
1.2: Volcanic Forcing
Volcanic eruptions have the potential to have negative or positive feedback mechanisms on climate.
Negative feedback results in climate cooling and positive feedbacks result in climate warming.
Figure 3: Diagram indicating the effects of stratospheric aerosols on the atmosphere; Robock, (2003) adapted from
Robock, (2000)
Figure 3 shows how large volcanic eruptions with high SO2 concentrations are ejected into the
troposphere and stratosphere at ~20-25km in altitude, they are able to influence climate resulting in
cooling (Robock, 2003; Coffey and Mankin, 2003; Dawson, 1992; Wanner et al., 2008). Aerosols

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entering the stratosphere can alter albedo in turn causing backscattering of solar radiation (Robock,
2003) or negative radiative forcing (Crawley, 2000). Zielinski, (2002) states that only large explosive
equatorial eruptions have the capacity to alter global climate for a number of years.
Huybers and Langmuir, (2009) argue that volcanic activity may present a positive feedback
mechanism for deglaciation and atmospheric CO2, based on 2-6 times elevations in background
eruptive frequency during 12-7ka, consistent with CO2 concentrations within ice cores. Huybers and
Langmuir, (2009) State that deglacial processes may increase volcanic eruption frequency, as later
discussed in chapter 4, which in turns produces greater atmospheric co2 and warming, further
enhancing deglaciation.
Overall it is believed that the complex interaction between orbital, solar and volcanic forcing are
responsible for the dramatic climatic changes experienced throughout the early Holocene (Shindell,
2013; Mayewski et al., 2004).
1.3: Anthropogenic Forcing
As previously mentioned Anthropogenic forcing, is related to the combustion of fossil fuels and the
release of GHG’s that enhance the natural greenhouse effect, shown in figure 4.

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Figure 4: Representation of the natural greenhouse gas effect. Higher levels of Methane, CO2, chlorofluorocarbons and
other GHG’s in the troposphere enhance the natural GHG effect, resulting in greater absorption of infrared radiation
resulting in less radiative reflection, consequently increasing the temperature of the lower atmosphere; Houghton,
(2010).
Observational records indicate unprecedented warming during the late twentieth century, now
understood to be the consequence of anthropogenic activity and the production of GHG’s (Mann,
2013; IPCC, 2013). The IPCC confirmed in 2013 that the threat from climate change as a result of
anthropogenic activity is irrefutable.
Our understanding of future climate change has been based on our understanding of the past.
Mann, (1999) and Mann et al., (1998) reconstructed temperature over the past millennia shown in
figure 5, commonly referred to as the ‘Hockey Stick Graph’.

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Figure 5: Graph depicting Northern Hemisphere Temperature changes over the last millennia, based on climate proxies
and historical records; Mann, (1999)
Mann and Jones (2003) reconstruct Northern and Southern hemisphere temperatures to support
Mann, (1999) by identifying a global temperature trend for increasing temperatures. Both figures 6a
and b) indicate an accelerated increase in temperature, since ~1870, this has been attributed to
Anthropogenic climate change by the release of GHG’s since early industrial times.

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Figure 6a and b): Graphs show northern and southern hemisphere temperatures over last 2 millennia; Mann and Jones,
(2003)
Section 2: Contemporary and Future Climate Change
The IPCC confirmed in 2013 that the threat from climate change as a result of anthropogenic activity
is irrefutable; this therefore highlights the significant need for an improved understanding of the
climate system in order to better model and predict the future. The IPCC, (2013) released a series of
climate modelling predictions in the recent AR5 summary report shown in figure 8, based on current
climate observations and modelling trends indicated in figure 7.

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Figure 7: Global graphs comparing modelling results and recorded observations for the last 100years; Yellow panels
indicate Temperature change; White panels indicate sea ice extent; blue panels indicate ocean heat content. Modelling
which accounts for only natural forcing, fails to match the observed changes in Land and ocean temperature changes,
therefore indicating that climate change is not a direct result of natural processes, which only the combined effect of
natural and anthropogenic forcing can account for the unprecedented warming observed since the late twentieth
century; IPCC, (2013)

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Figure 8: Climate modelled scenarios showing relative change between RCP2.6 (1986-2005) and RCP8.5 (2081-2100)
diagram A) precipitation B) sea ice extent C) ocean surface PH; IPCC, (2013)

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2.1: Contemporary Climate Change and Implications for Geological Activity
McGuire, (2010) discusses potential periods of previously enhanced geological activity associated
with periods of abrupt climate change. McGuire, (2010) assumes uniformitarianism when
considering past and future geo responses to climate change.
McGuire, (2010) infers that at high latitudes, seismicity and volcanic activity may increase through
ice mass loss and crustal adjustment and modulation, based on work by; Turpeinen et al., (2008);
Hampel et al., (2010); Pagli and Sigmundsson, (2008); Sigmundsson et al., (2010). Mcguire (2010)
further suggests that a likely consequence could be increased submarine failures and tsunami’s,
based on Tappin, (2010).
McGuire, (2010) argues that in oceanic settings increased volcanic and seismic activity should also be
expected through crustal loading associated with sea level rise, which may again result in greater
submarine failure and tsunami occurrence.
The conclusion drawn by McGuire, (2010) is strictly uniformitarian, inferring that past periods of
exceptional climate change are associated with a geo response and therefore future climate change
shall likely result in a geo response suggesting increased frequency of volcanic and seismic events
may occur and in turn likely increases in Submarine failures and Tsunami’s.
Liggins et al., (2010) offer a comprehensive regional assessment into the potential geopheric
responses that may potential occur in response to climate change scenarios based on the IPPC AR4
projections. These conclusions are in agreement with those of McGuire, (2010), but again assume
uniformitarianism basing potential responses on ‘associated’ previous responses, the limitations of
this is that the majority of these associations between previous geological responses to climate
change remain theoretical and are yet to be empirically proven, therefore modelling applied
scenarios present large uncertainties.

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Overall, this could be considered as a narrow and biased point of view, with supporting literature
intent on proving the link between increased geological activity and climate change. It should also be
noted that the majority of literature has as yet failed to prove more than circumstantial and
theoretical links, citing age proximity as cause and effect as a suitable triggering mechanism
(McGuire, 2010; McGuire et al., 1997; Smith et al., 2011, 2013; Garziglia et al., 2003; Trincardi et al.,
2003). The literature relies heavily on modelling, with inherent uncertainty, which should not
necessarily be taken as truth in the context of future climate change, given the variety and volume of
uncertainty associated with future climate.
In conclusion, McGuire, (2010) offers a well synthesised literature review in support for climate
forcing of geological hazards. However, what this paper attempts to do, is critically review and
evaluate arguments both for and against climate forcing of geological hazards, attempting to deliver
an unbiased and balanced argument in order to conclude and determine to what extent future
climate change may have the potential to trigger geological activity.
Section 3: Climate Change Uncertainty
Mitchell and Hulme, (1999) identify inherent climate uncertainty to be the result of deterministic
chaos presented by the complexities intrinsic to the climate system by external and internal
forcing’s, feedbacks and complex interactions, highlighting epistemic and aleatory uncertainties. The
complexity of the climate system as whole can be seen in figure 9.

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Figure 9: Schematics of the Earth’s Climatic System, depicting the complexities between the hydrosphere, Atmosphere,
Geosphere, Biosphere, Cryosphere, Solar and Anthropogenic interactions; Houghton, (2010).
Increasing complexities present increasing uncertainties as noted by Schneider, (1983 and 2002)
Oreskes et al.,(2010), Houghton (2010) and Maslin (2013) which can lead to the uncertainty
explosion, shown in figure 10, and the cascade of uncertainty shown in figure 11.
Figure 10: The uncertainty explosion, suggests multiplying uncertainty of future consequences associated with political,
economic, sociological, physical responses; Schneider, (2002) modified after Jones, (2000)

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Figure 11: the cascade of uncertainties to be regarded when developing climate scenarios; Houghton (2010) sourced
from IPCC, (2001)
As discussed by Maslin, (2013) models have limitations based on their closed system simplicities, as
well as the limited understanding of the physical user with regard to the complexities of the physical
system. Epistemological and ontological uncertainties with regards to climate modelling are
discussed at length by Foley, (2010) the summary of which can be seen in Figure 12.

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Figure 12: Climate Modelling uncertainties, arising from aleatory uncertainty associated with the natural climate system
and epistemological and ontological uncertainty arising from climate modelling; Foley, (2010).
Overall the majority agree that although large uncertainties exists with regard to climate change and
future responses, it is however likely that based on previous global changes, since not only the start
of the interglacial warming trend but also accelerated warming by anthropogenic activities, are likely
to result in continued temperature increases, continued ice mass loss and increased sea level rise
(IPCC, 2013). These three responses are considered to have been responsible for enhanced geo-
hazards during previous periods of climate changes during the Quaternary, these considerations will
be critically reviewed later in this paper.

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Chapter 3: The Quaternary
According to Elias, (2013) the Quaternary spans the last 2.6my, and is separated into two geological
epochs the Pleistocene (2.6my-11ky BP) and the Holocene (11Ky to present). This period of time is of
significant importance to climate scientists in order to better understand climate change and
potential links to geological hazards. The Quaternary is the most understood period of time
demonstrating dramatic climatic shifts with roughly 50 large scale oscillations between glacials
lasting on average 100,000yrs and interglacials ~10,000yrs. The Quaternary contains evidence of
dramatic climate shifts and responses from the atmosphere and cryosphere that have yet to be
observed in recorded history, and as noted by Elias, (2013) can offer extensive insight into potential
future climate change scenarios and feedbacks.
Section 1: Glacial/Interglacial Cycles
As previously noted in chapter 2, glacial/interglacial cycles are thought to have been controlled by
Milankovitch cycles, see figure 2; chapter 2, section 1. Glacial/Interglacial cycles during the
Quaternary period can be seen in figure 13.
Figure 13: Graph showing ocean temperature oscillations, based on oxygen isotope ratios within benthic foraminifera
over last 3my. Warm interglacial periods represented by odd numbered peaks, cold glacial periods indicated by even
numbered troughs; Elias, (2013) adapted from Lisiecki and Raymo, (2005)
The last Glacial Maximum concluded ~20 ca Ky BP (Smith et al., 2013) during the late Pleistocene,
giving way to a warmer period known as the current Interglacial. Wide spread ice mass loss and ice
sheet decline, lead to rapid sea level rise, and abrupt climate oscillations through the late

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Pleistocene and early Holocene ~11,650-7000BP (Smith et al., 2013), this period is often referred to
as the late Pleistocene-early Holocene transitional period. This paper will be focusing on potential
geological events which may have occurred as a result of deglacial processes during the interglacial
and responses to abrupt climate shifts.
Section 2: Abrupt Climatic Change during the Quaternary
This paper will discuss two notable periods of exceptionally abrupt climate change during the
Quaternary late Pleistocene-early Holocene transition, where warm interglacial conditions reverted
rapidly back to glacial with respectively cooler conditions, these are the Younger Dryas stadial and
the 8.2Ka Cold Event, indicated in figure 14.
Figure 14: An Overview of Quaternary Climatic Changes, and consequential temperature oscillations; Alley, (2000)

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2.1: The Younger Dryas
The transitional phase between from glacial to interglacial, was not uniform but punctuated by an
abrupt cold stadial known as the Younger Dryas (Ruddiman and Duplessey, 1985; Broecker et al,
1988). The Younger Dryas (YD) has been dated between 12,900-11,700 calibrated years before
present by Carlson, (2013), who further gives detailed discussion of the climate impacts associated
with the YD across the globe.
Broecker et al., (1988) discuss various hypotheses for the triggering of the YD, concluding that the
likely cause was theorised by Johnson and McClure, (1976) who cited meltwater discharge from
North America as a probable cause. This was supported by Rooth, (1982) who concluded that
meltwater discharge could halt north Atlantic deep water production. Broecker et al., (1985) and
Rind et al., (1986) further supported this theory demonstrating climate characteristics of the YD as a
likely impact of the North Atlantic conveyor belt discontinuing. Broecker et al., (1989) concludes
based on isotope data that the conveyor belt did shut down during the YD and that meltwater
outflow into the North Atlantic did result in the YD cold period.
The exact triggering mechanism which initiated the YD remains unknown and controversial. Even the
source and method of meltwater discharge remains a source of much debate, with conclusions
ranging from the drainage of Lake Agassiz (Broecker et al., 1989), to an impact hypothesis (Firestone
et al., 2007; Van Hoesel et al., 2014) as well as Dansgaard-Oeschger cycles (Teller, 1990; McGuire et
al., 2002; Broecker et al., 2010)
Teller, (1990) concludes that glacial lake Agassiz shown in figure 15, drained through the great lakes
and St. Lawrence valley into the north Atlantic, shown in figure 16, a theory also shared by Clark et
al., (2001) with an estimated outburst volume ~30,000m3 (Broecker et al., 1989).

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Figure 15: Map depicting the location of Lake Agassiz and Laurentide ice sheet, typically routed through the Mississippi
to the Gulf of Mexico, (Broecker et al., 1989).
Figure 16: Lake Agassiz re-routed through great lakes and St. Lawrence valley into the North Atlantic during the YD, as a
result of ice sheet advance, (Broecker et al., 1989).

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Later work by Teller et al., (2002) concludes that not only did a large outburst from LA possibly result
in the YD cooling event but later outbursts may have been responsible for the Preboreal Oscillation
and the 8.2ka cold event by again triggering changes in ocean circulation resulting in climatic
changes.
However Lowell et al., (2005) challenged this hypothesis, concluding an alternative triggering
mechanism for the YD should be sought based on geomorphological and chronological data which
indicated that meltwater corridors proposed for the drainage of LA were still ice damned. Lowell et
al., (2005) conclude that there was no catastrophic meltwater release from LA during the onset of
the YD, and therefore an alternative mechanism for the shutdown of thermohaline circulation (THC)
ought to be sought. It is worth noting that Lowell et al., (2005) still maintain that the YD cold event
was triggered by a break down in the North Atlantic THC, but the chain of events did not begin with
LA. This is in agreement with Teller et al., (2005) who also noted that absent flood deposits and
outflow channels in the great lakes suggest that deglaciation of the area was incomplete, preventing
outflow.
An alternative outflow route could be the Clearwater-Athabasca-Mackenzie (CAM) river basin into
the Arctic Ocean followed by North Atlantic, suggested by (Teller, 2013; Teller et al., 2005; Condron
and Winsor, 2012; Tarasov and Peltier, 2006; 2005; Murton et al., 2010; Upham, 1895; Smith and
Fisher, 1993; Teller and Thorleifson, 1983; Zoltai, 1967; Elson, 1967). Teller, (2013) presents
evidence for both eastward drainage through the great lakes and north-western drainage through
the CAM basin, concluding that as yet no definitive conclusion has been made with regards to LA
outflow route.
Furthermore Broecker et al., (2010) based on Barber et al., (1999) suggests that the rate of onset for
the YD, cannot be attributed to catastrophic outflow from LA as the rate of onset is inconsistent for
catastrophic events based on the rate of onset for the 8.2ka cold event. Therefore based on the
work by Lowell et al., (2005) and Broecker et al., (2010) there may be enough reasonable doubt
surrounding the theory of LA as a triggering mechanism for the YD to warrant identification of
alternative hypothesis.

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Broecker et al., (2010) suggest that the YD, may not have been the result of catastrophic drainage or
meltwater pulses, but a natural processes in the ongoing transition from glacial to interglacial
conditions, and is a natural punctuation in the climate conditions that may or may not be the result
of Dansgaard-Oeschger events.
A further alternative conclusion to the Younger Dryas is that of the Younger-Dryas-Impact-
Hypothesis (YDIH), which proposes that an ET (Extra-terrestrial ) impact occurred ~12.9Ka BP, over
north America resulting in the Youger Dryas (Firestone et al., 2007; Pinter et al., 2011; Van Hoesel et
al., 2014). The theory suggests that impact force and heat may have been significant enough to
destabilise the Laurentide ice sheet residing over North America, providing a large source of
meltwater that may have been released into the North Atlantic or Arctic. The meltwater route is also
suggested by Teller et al., (2005, 2013) although the source of meltwater significantly differs. The
YDIH was supported by 12 impact markers used to evidence the event.
Van Hoesel et al., (2014) and Pinter et al., (2011) conclude that the evidence to support this event
fails to support the hypothesis. Pinter et al., (2011) argues extensively against the evidence used
suggesting that evidence may have either been misinterpreted, ambiguous evidence was
manipulated to suit a chain of argument, that can be explained by alternative causes. Van Hoesel et
al., (2014) propose further research areas. Overall there is very little support for the YDIH, due to
lack of supporting and valid evidence.
Overall, the causal mechanism and source for the YD remains uncertain as does the exact date of the
event (Van Hoesel et al., 2014). Meltwater triggering and AMOC shut down is cited as the most likely
trigger, but the source of meltwater remains controversial.
2.2: The 8.2Ka Cold Event
Beget, (1983) found evidence of a neoglaciation in the Northern hemisphere between ca 8500-
7500yr BP, concluding that a global cooling event must have occurred. This was the first recognition
of the 8.2ka cold event (Wang et al., 2005). Dansgaard, (1987) supported this through Greenland ice

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core records which indicated a cold event between 8.4-8.0 cal Ka BP. The 8.2Ka cold event is now
recognised as a period of abrupt climate change in the North Atlantic.
The 8.2ka cold event is believed by many to be the response to freshwater influx from glacial retreat,
impacting the Atlantic Meridional Overturning Circulation (AMOC). The link between freshwater,
ocean circulation and climate change was first proposed by Rooth, (1982) and later developed by
Broecker et al., (1985; 1988; 1989; 1990) Johnston and McClure, (1976) and Broecker, (1994; 1997;
1998;). As the theory stands large influxes of fresh and meltwater into the North Atlantic are capable
of halting North Atlantic Ocean Circulation, preventing the AMOC from delivering heat to high
latitudes resulting in abrupt cooling events (Li et al., 2012; Tornqvist and Hijma, 2012; Alley, 2007;
Broecker et al., (1985; 1988; 1989; 1990; Broecker,1994; 1997; 1998) in the northern hemisphere
and warming events in the southern hemisphere producing a ‘see-saw’ effect (Broecker, 1998; Alley,
2007). Knutti et al., (2004) supported this using coupled ocean-atmosphere-sea ice models to
effectively model the 8.2ka event and climate impacts.
The triggering mechanism for the fresh water influx is believed by many (Li et al., 2012; Tornqvist
and Hijm; 2012; Smith et al; 2011, 2013; Barber et al 1999; Alley et al., 2003; Alley and Augustsdottir,
2005; Lajeunesse and St-Onge, 2008., Cheng et al., 2009; Teller et al., 2002) to be a freshwater
outburst from glacial Lake Agassiz, with many arguing age proximity between the LAO outburst and
the 8.2ka cold event as a causal link through a freshwater influx and breakdown of the AMOC as a
triggering mechanism.
Li et al., (2012) note that uncertainty regarding the date of the 8.2ka event has prevented the
confirmation of causal links and in particular age proximity to the freshwater outburst of Lake
Agassiz. Li et al., date the LAO drainage to 8.18-8.31ka, and the 8.2ka event to 8.15-8.25ka based on
work by Thomas et al., (2007) Kobashi et al., (2007) and Cheng et al., (2009), inferring that the
drainage of LAO resulted in a rapid oceanic and atmospheric response to the influx of freshwater,
supporting cause and effect theory for age proximity of events.
Overall the causal mechanism of the 8.2ka event is most widely recognised and accepted as the final
drainage of LAO, resulting in a second shut down of the AMOC, resulting in abrupt cooling.

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Chapter 4: The Impact of Climate Change on Volcanoes
McGuire, (2010) argues that climate change triggers a geological response such as volcanic activity,
furthermore implying that contemporary climate change may consequentially induce volcanic
activity. Therefore, this Chapter aims to discuss supposed periods of increased volcanic activity and
that may correspond to periods of past rapid climate change. Secondly this chapter will review the
methods by which climate change may or may not alter volcanic processes through glacial-deglacial
cycles and sea level rise. Furthermore this chapter seeks to determine the extent to which
contemporary climate change may influence future volcanism.
Section 1: Volcanism and Past Climatic Change
Previous abrupt climate changes during the Quaternary have been linked to increased volcanism,
(Rampino, 1979; Hall, 1982; Tuffen, 2010; Watt et al., 2013; McGuire et al., 1997). Increased coastal
volcanic activity in the Mediterranean and New Zealand has been attributed to sea level rise during
the early Holocene as a result of climate change (Smith et al., 2011; Firth et al., 2005; McGuire et al.,
1997) supported by Zielinski et al., (1994; 1996) who identified increased volcanic aerosols within
the Greenland ice cores.
Zielinski et al., (1994) and Zielisnki et al., (1996) observed greatest concentrations between 13-7Ky
BP, during the Late Pleistocene-Early Holocene transitional phase, with the greatest volcanism
occurring between 9-7ky BP, in accordance with the final stages of global deglaciation. This
corresponds with increased Tephra emplacement observed by McGuire et al., (1997) in
Mediterranean Sea floor deposits (Smith et al., 2011).
Globally eruptive records show an increased frequency of volcanism between 12-7Ky BP in
deglaciating regions with a 2-6X rise in background volcanism (Huybers and Langmuir, 2009).
Globally, regionally and locally there is a statistically significant relationship between past climate
warming and increased volcanism, (Tuffen, 2010; Jellinek et al., 2004; Nowell et al., 2004; Huybers
and Langmuir, 2009; Major and Newhall, 1989) supporting the notion that previous climate change

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elicited a volcanic reaction, presenting evidence for uniformitarian cause and effect, when predicting
future volcanic responses to climate change.
Evidence for increased eruptive intensity is also discussed by Zielinski, (2000) Tuffen, (2010)
McGuire, (2010) Firth et al., (2005) based on the evidence of Zielinski et al., (1994; 1996), Zielinski
(2000) argues that not only did periods of rapid climate change correspond to increased volcanic
frequency but also increased intensity and magnitude of events. This infers future climate warming
could illicit potentially increased eruptive frequency and intensity, presenting increased risk from
volcanic hazards if previous patterns were to be repeated.
Increased volcanism as a result of rapid climate change during the Quaternary has been attributed to
deglaciation following the last glacial maximum; (Zielinski, 2000; Tuffen, 2010; McGuire, 2010;
Rampino, 1979; Hall, 1982; Grove, 1974; Smith et al., 2011; McGuire and Maslin, 2013; Watt et al.,
2013) inferring that glacial-deglacial cycles may modulate volcanic activity.
McGuire, (2010) assumes the uniformitarian stance assuming that previous volcanic responses to
climate change may occur again, presenting high risk to northern latitudes and oceanic and coastal
volcanoes.
Section 2: Effects of Glacial loading and Deglacial Unloading on Volcanic
Processes
Glacial-deglacial cycles can influence the rate of decompression melting of magma (Huybers and
Langmuir, 2009; Jull and McKenzie 1996; Slater et al., 1998; Schmidt et al., 2013; Maclannan et al.,
2002). During glaciation ice weight results in lithospheric flexure, preventing adiabatic
decompression melting of magma, Slater et al., (1998) explains that mantle upwelling is halted until
the solidus pressure state is returned. When deglaciation begins during an interglacial phase,
pressure reductions through ice mass loss allows for lithospheric rebound, temporarily increasing
the rate of magma production through melt generation by ~100-140% (Schmidt et al., 2013).

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An analysis of volcanic events during the Holocene by Huybers and Langmuir, (2009) supports
deglaciation as a triggering mechanism of increased volcanism. Nakada and Yakose, (1992) support
the theory through surface mass transfer of water and ice volumes upon the lithosphere resulting in
pressure changes, capable of increasing magma production triggering volcanic activity.
Tuffen, (2010) confirms a statistically significant correlation between deglacial unloading and
increased volcanism, but recognises that timing of responses have been variable, which may be a
consequence of ice mass thickness, lithospheric thickness and characteristics such as geology and
rheology. Morner, (1971) states that loading depression is 1/3 of the thickness of the ice, however
this may vary depending on lithological structure, giving values between 0.25 and 0.33 times the
thickness. This may therefore account for the variations in volcanic responses to deglaciation.
Jull and McKenzie, (1996) believed volcanic response to deglaciation would be instantaneous,
however Slater et al., (1998) identified a 1-3Kya timescale response of Icelandic Volcanoes to
deglaciation, supporting Tuffen, (2010) and accounting for variable volcanic responses.
The analysis of explosive volcanism in ice land following the last glacial maximum, observed a 20-30x
increase in the eruptive rate of magma roughly 11Kya, coinciding with final stages of ice retreat
(Slater et al., 1998). This supports the theory of deglaciation as a triggering mechanism for increased
volcanism through increased decompression melting.
Sigvaldason et al., (1992) and Kelemen et al., (1997) proposed that increased magma production due
to magma pooling and storage within the volcanic system during glacial times, is then released
through pressure reduction during deglaciation due to ice mass loss, contributing towards increased
eruptive rates.
Gudmundsson, (1986) argues pressurisation of magma reservoirs within the main chambers of
volcanoes may occur during glaciation due to ice loads, preventing eruptions and increasing the
available store of magma, allowing for reservoir tapping, during deglaciation.

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It is possible that increases in eruptive rate may be the result of the combined effect of, increased
decompression melting and magma generation, magma storage and pooling as well as reservoir
pressurisation during glacial times. Based on the evidence discussed it can be inferred that there is a
relationship between deglaciation and unloading of ice masses on volcanism. Resulting in previously
known examples of increased eruptive rates following deglaciation in Iceland, combined with the
successful modelling of these events by Jull and McKenzie, (1996) and Slater et al., (1998) confirming
this. Furthermore the statistically significant relationship between volcanism and unloading by
Tuffen, (2010) confirms this relationship.
Overall evidence suggests there is a relationship between deglaciation and increased volcanic
activity, which therefore supports the notion that future climate change and associated ice mass
losses may result in increased eruptive frequencies presenting increased risk from volcanic hazards.
Section 3: Effects of Sea Level Rise on Volcanic Processes
During deglaciation water locked up in ice is returned to the oceans, resulting in eustatic sea level
rise, this process is referred to as post glacial mass transfer by McGuire, (2010) and surface mass
redistribution (of water volumes) by Nakada and Yakose, (1992). The Early Holocene is a known
period of rapid sea level rise (Smith et al., 2011), and has been closely attributed with increased
volcanic frequency by McGuire et al., (1997) McGuire, (2010) Firth et al., (2005) and Smith et al.,
(2011).
McGuire et al., (1997) proposes that the redistribution of water volumes on the Earth’s surface
results in stress accumulations, that have may have triggered increased volcanic frequency amongst
coastal and island-arc volcanoes, during and after the early Holocene sea level rise (EHSLR). McGuire
et al., (1997) and Firth et al., (2005) identify a short term and long term volcanic response to sea
level rise.

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Short term response is considered to be the result of changes to the internal stress regime through
rising water tables, increasing the likelihood of pore pressurisation promoting phreatic activity as
magma interacts with saturated flanks, resulting in increased explosive volcanism. Rapid loading of
adjacent faults and margins may increase internal instabilities, promoting magma migration,
increasing the eruptive potential as pathways are opened. Increased rates of marine and coastal
erosion of the volcanic slopes could promote flank collapses, triggering eruptions. Furthermore
increased loading pressures along continental shelves and margins may increase confining pressures
within the main chamber potentially triggering eruptions.
Long term volcanic response, is attributed by McGuire et al., (1997) to melt ascension through
mantle loading due to increased surface pressures from increased water volumes. McGuire et al.,
(1997) conclude that finite element modelling indicates adjacent sea level rise could trigger
eruptions through a reduction in compressive stressors within the volcanic edifice. This supports
work by McNutt & Beavan (1987); McNutt, (1999) and McGuire et al. (1997) who infer that oceanic
loading and flexure results in reduced shallow compressive stressors and increased compressive
stressors at depth, in effect squeezing magma. This further supports the work by McNutt and
Beavan (1987) who concluded that eruptions at Pavlof, an Alaskan volcano in the North Pacific, may
be the result of sea level modulation. McNutt and Beavan, (1987) cite compressive strain
accumulation, through adjacent continental eustatic loading, resulting in magma squeezing and
emplacement.
McGuire et al., (1997) relates volcanic activity to sea level rate in the Mediterranean spanning the
last 80Ka, observing a comparable like for like trend between volcanic activity and sea level rise,
indicated in figure 17.

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Figure 17: Indicates that as sea level rises, the periodicity between tephra emplacing events decreases, inferring that sea
level rise results in an increase in eruptive events; McGuire et al., (1997)
However in order to present a balanced and unbiased view as to how volcanism may be affected by
sea level rise, it is important to consider alternatives to the argument presented by McGuire et al.,
(1997) and again in McGuire, (2010), by counteracting this with an alternative view and possible
relationship that was not considered in McGuire., (2010). Arguments presented by Lund and
Asimow, (2011) and Mason et al., (2004), suggest that periods of increased sea level result in
reduced volcanic activity, and furthermore that periods of sea level unloading result in increased
volcanic activity, presenting an inverse argument, that McGuire., (2010) fails to recognize.
Lund and Asimow, (2011) assume the position of Jull and McKenzie, (1996) and Slater et al., (1998)
who argue that increased volcanism occurs in response to glacial unloading, and reduced volcanism
occurs during loading, Lund and Asimow therefore adopt this approach towards loading effects on
the crust and attempt to apply this to the oceanic crust with regards to eustatic loading as opposed
to glacial loading. Lund and Asimow, (2011) conclude that periods of sea level unloading should
result in increased activity, due to the removal of weight and pressure, increasing decompression
melting, followed by sea level loading resulting in a marked decrease in volcanic activity. This
theoretical argument is supported by modelling, which infers that peaks in magmatic flux occurs in

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response to sea level unloading during MIS 2+4, furthermore during sea level rise, the minimum
simulated flux is observed, this is shown in figure 18.
Figure 18: Indicates increased melting response to change in sea level inferring that magmatic flux during sea level falls
during MIS stages 2 and 4, with reduced magmatic flux during sea level rise; Lund and Asimow, (2011) spreading rate is
indicated by colour (75mm/yr Green; 30mm/yr Black; 10mm/yr Red)
Lund and Asimow, (2011) conclude that potentially climate may have the capacity to influence upper
mantle melting and therefore in turn volcanic activity.
Mason et al., (2004) supports this through there identification of volcanic seasonality in global,
regional and local eruptions records spanning the last 300yrs. Seasonality of eruptions show
significant correlation to environmental changes, which are linked to surface deformations in
response to the hydrological cycle. In particular Mason et al., (2004) observed a global peak in
eruptive rate during sea level falls, and in particular peak eruptions at Pavlof volcano in the north
pacific, which contrasts the conclusions of McNutt and Beavan, (1987) who associated eruptive
peaks with sea level rise. Further work should be undertaken in order to determine which hypothesis
is correct, if any at all. Furthermore Mason et al., (2004) find an absence of regionally significant
peaks in volcanism, during periods of sea level rise. Concluding that statistically enhanced volcanism
occurs during recurring annual sea level falls.

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McGuire, (2010) argues that not only will sea level rise increase the likelihood of volcanic eruptions,
but furthermore explosive volcanic eruptions as a result of volcanic flank saturation promoting
phreatic activity through magma intrusions interacting with elevated pore water pressures within
the flanks. This is supported by Liggins et al., (2010) who conclude that elevations in precipitation as
a result of climate change may increase pore water pressures within volcanic flanks, leading to
saturation and increased episodes of phreatic activity.
Capra, (2006) expands upon this discussing the impact of precipitation changes due to climate
change on volcanic flank stability, citing precipitation elevations as a triggering mechanism for
volcanic flank collapse, and possibly a trigger for eruptions. Capra, (2006) supports this with the
chain of events leading to Mt. St. Helens eruption 1980; an eruption triggered by a flank collapse,
initially triggered by an earthquake. Furthermore Capra, (2006) proposes that ‘Globally Synchronous’
collapses occurred following the LGM. Tappin, (2010) concludes that Potential increases in volcanic
flank collapses could increase the frequency of tsunami generating events.
Section 4: Contemporary Climate Change and Volcanic Activity
Overall this chapter concludes that periods of increased volcanism have been associated with
climatic change during the late Quaternary, confirming a link between climate change and
volcanism. Secondly, that increased volcanism can occur in response to deglaciation and increased
decompression melting. Thirdly, that the impact of eustatic loading/unloading is yet to be fully
understood and determined, necessitating further research. Furthermore changes in precipitation
are likely to promote phreatic activity, potentially triggering flank collapses and explosive eruptions,
with possible increases in tsunami generation.
Therefore based on the conclusions drawn, there is potential for deglaciating regions to experience
increased volcanism. The extent to which sea level rise will impact volcanism is yet to be
determined, from the view point of McGuire, (2010) oceanic and marine volcanism will increase,
however based on the views of Lund and Asimow, (2011), Volcanism will decrease, since both
arguments remain theoretical further studies are required. Furthermore regions liable to experience
increased precipitation could experience increasing phreatic activity, flank collapses, eruptions and
tsunami, whereas regions anticipating reduced precipitation may experience, less volcanic activity.

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Chapter 5: The Impact of Climate Change on Seismicity
McGuire, (2010) states that climate change results in crustal phenomena such as seismic activity,
furthermore suggesting that future climate change may result in seismic responses. Therefore, this
chapter aims to discuss previous climatic changes linked to phases of altered seismic frequency,
followed by reviewing the mechanisms by which climate change may modulate volcanic activity
through deglacial processes such as post glacial rebound and Eustatic loading through sea level rise.
Furthermore this chapter will determine to what extent future climate change is likely to alter
seismic frequency.
Section 1: Seismicity and Past Climatic Changes
Increased seismicity has been linked to deglaciation following the LGM, (Jamieson, 1865, 1882;
Kolderup, 1930; Muir-Wood, 2000; Gudmundsson, 1999; Wu et al., 1999; Chappell, 1974; Stewart et
al., 2000; Fjeldskaar et al., 2000; Dehls et al., 2000; Morner, 1978; Manga and O’Connell, 1995;
Hampel et al., 2010., 2013) particularly in formerly glaciated areas such as Fennoscandia.
Bungum et al., (2005) noted elevated seismicity following a period of aseismicity attributed to the
weight and removal of the ice load overlying the Fennoscandian crust ~10Ky BP. Stewart et al.,
(2000) supports Gregerson and Basham (1989) who concluded that “Increased seismicity
immediately follows deglaciation” supported by significant faulting in Fennoscandia following
postglacial times, during rapid deglaciation(Lagerback, 1979; Lagerback and Witscard, 1983; Muir-
Wood, 1989, 1993; Talbot, 1999; Stewart et al., 2000). This is supported by Hampel et al., (2010)
based on modelling by Turpeinen et al., (2008) indicating elevated slip rates ~15m between 10.5-
8kya. This is further supported by Stewart et al., (2000) Lagerback and Sundh (2008) Olesen, (2013)
and Olesen et al., (2004) Table 1, summarises postglacial faults in Finland, Norway and Sweden.

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Table 1: Post Glacial Faults documented in Finland, Norway and Sweden (Olesen, 2013; Modified from Olesen et al.,
2004; Lagerback and Sundh, 2008; Stewart et al., 2008; Dehls et al., 2000).
Faults that have been determined as ‘almost certainly’ Neotectonics in Fennoscandia by Bungum,
(2005) are shown in Table 2.
Table 2: Norwegian post glacial faults considered to be almost certainly neotectonics and created through single events
based on the outcomes of the NEONOR Project (Bungum et al., 2005; Dehls et al., 2000)
Post glacial uplift in Fennoscandia reached 850m, resulting in ~30MPa of crustal stress, which
Gudmundsson, (1999) concluded to be significant in initiating and reactivating seismogenic faults.
Gudmundsson, (1999) further suggested that reactivation of tensile and shear fractures may
increase hydraulic conductivity of upper crustal rocks. Supporting work by Costain and Bollinger,
(1996) who argue that increased hydrostatic fluid pressures within crustal rocks can promote
increased seismicity through fluid presence reducing the strength of rock asperities (Griggs, 1967;
Wylie and Mah, 2004).

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Overall it is understood that increased seismicity occurred in Fennoscandia during the final stages of
deglaciation ~10Ky BP during the early Holocene, as a consequence of climate changes and
deglaciation following the LGM. Furthermore Hampel et al., (2010) argue that postglacial seismic
amplification was not restricted to large ice sheets but also extends to smaller ice masses, supported
by increased seismicity along faults in American Basin-Range Province, potentially suggesting that
the effect of deglaciation on seismicity may have been greater than previously understood. Further
suggesting potential seismic response to climate change and deglaciation may not be constrained to
locations bearing ice sheets, but also smaller glaciated mountains and valleys, presenting potentially
greater seismic risk associated with future climate change.
Section 2: Post Glacial Rebound and Seismic Frequency
Deglaciation results in surface mass redistribution of water and ice loads as well as crustal
deformation, known as Glacio-Hydro-Isostasy (Stewart et al., 2000; Jamieson, 1865; 1882; De Geer,
1888). Glacio-Hydro-Isostasy is the process by which the earth responds to changes in water or ice
load variations upon the surface throughout glacial/Interglacial cycles (Lambeck, 2011).
Glacio-Isostasy takes place when surface loading during ice sheet growth results in crustal
subsidence or lithospheric flexure (Watts, 2001). When the ice sheet recedes unloading occurs
resulting in crustal rebound/ Isostatic uplift, (Lambeck, 2011) demonstrated in figure 19. Glacio-
Isostasy is typically accompanied by intense faulting and seismic activity (Morner, 1978).
Hydro-Isostasy occurs when ice sheets expand resulting in removal of water from the ocean or
diminish resulting in addition of water to the ocean, consequently causing the oceanic crust to
rebound or flexure, (Lambeck, 2011; Watts, 2001) demonstrated in figure 20.

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Figure 19: Demonstrates the effects of glacial loading on the crust and resulting flexure of the lithosphere; Stewart et al.,
(2000) adapted from Muir-Wood, (1989) and Fenton, (1992)
Figure 20: Demonstrates the effects of unloading and Glacio-Isostatic Rebound; Stewart et al., (2000) adapted from
Muir-Wood, (1989) and Fenton, (1992)
Chappell, (1974) supports the theory of Glacio- Hydro-Isostasy concluding that relative sea level rise
following the last deglaciation may have resulted in ~8m of average depression across oceanic
basins, with rebound generating ~16m of mean uplift of continental areas over the last 7Kya.

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Manga and O’Connell, (1995) present the possibility that climate variations can impact mantle
dynamics based on modelling the effects of surface strain rates on the teconosphere. Stewart et al.,
(2000) support this by concluding that late Pleistocene deglaciation affected large areas
encompassing both elastic lithospheric flexure and mantle flow, resulting in sizeable crustal
deformation that continues as present.
Hampel et al., (2013) use finite element modelling to examine the reaction of faults to loading and
unloading. The model is applied to Northern Scandinavia where increased seismicity corresponds
with deglaciation, shown in figure 21.
Figure 21: Shows the direct correlation between glacial unloading and increased slip rates through ~2m unloading of the
Fennoscandian ice sheet, diagram further indicates aseismicity during ice presence. Source: Hampel et al., (2010), based
on work by Talbot, (1999) and Milne et al., (2001)
Modelling by Hampel et al., (2010) indicates aseismicity during the existence of the Fennoscandian
ice sheet, as a result of seismic suppression through surface loading (Stewart et al., 2000) supporting
Bungum et al., (2005) who also reported elevated seismicity following a period of aseismicity in
Fennoscandia ~10Ky BP. The timing of modelled elevated slip rates ~10.8Kya BP, corresponds with
paleo-seismological records,(Morner, 2004; Bungum et al., 2005) linking theoretical and empirical
studies in order to support the notion of increased seismicity in Fennoscandia as a result of removal
of the Fennoscandian ice sheet during deglaciation, supporting the conclusion of Hampel et al.,

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(2010) that deglaciation did cause the period of increased seismicity in Scandinavia. This therefore
supports the notion of postglacial rebound as a trigger for increases seismic frequency.
Evidence of postglacial increases in seismicity due to rebound can also be found in the United States,
where the Wasatch (see figure 22) and Teton Fault (see figure 23) have indicate elevated slip rates
following the LGM (Byrd et al., 1994; McCaplin, 2002; Ruleman and Lagerson, 2002; Hetzel and
Hampel, 2005; Hampel et al., 2010) shown in figure 24.
Figure 22: Map depicting the location of the Wasatch Fault; Utah Geological Survey, (1996)
Figure 23: Map indicating the location of the Teton fault; Hampel et al., (2010)

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Figure 24: Graph indicating elevated slip rates along the Wasatch Fault during the LGM; Hampel et al., (2010)
Hetzel and Hampel, (2005) attribute Wasatch faulting to increasing slip rates through PGR from
regression of lake Bonneville and retreat of the Unite and Wasatch Mountain Glaciers. 3D modelling
indicates 69m uplift in agreement with palaeo-shoreline records. Modelling slip rates are further in
accordance with geological and palaeo-seismological data which shows triangulated evidence based
of quantitative evidence to support postglacial increases in seismicity through deglaciation processes
such as redistribution of smaller volumes of ice and water loads.
Teton faulting is linked to melting of the Yellowstone Ice cap and valley glaciers. 3D modelling by
Hampel et al., (2007) that original surface loading from Yellowstone Ice cap lead to ~80m crustal
subsidence around 22kya BP. Modelling infers a reduction in seismicity during ice accumulation,
followed by slip rate increase when deglaciation begins, with heightened rates occurring between
16-8kya BP, shown in figure 25, supported by palaeo-seismological data.

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Figure 25: Graph indicates the effects of ice loading on the Teton fault, with elevated slip rate between 16-8Ky BP;
Hampel et al., (2010)
Evidence for postglacial seismicity as a consequence of deglaciation and uplift may also be found in
the European Alps. 10m fault scarps have been identified and attributed to PGR (Ustaszewski et al.,
2008; Norton and Hampel, 2010; Hampel et al., 2010). Modelling by Norton and Hampel (2010)
resulted in the conclusion that increased seismicity may have been triggered by unloading and uplift
of the valley floor resulting in slip increases in ridge crests along zones of existing weakness
(Ustaszewski et al., 2008).
Palaeo-seismological data suggests that faulting in the Upper-Rhine may be responsible for the Basel
Earthquake of 1356, and is attributed to on-going alpine deglaciation (Hampel et al., 2010), inferring
that if deglaciation in alpine regions continues as is to be expected based on current Global Climate
Models (GCM’s) increased seismicity maybe likely resulting in future hazards and risks to
mountainous alpine regions.
Johnston, (1987, 1989) suggested seismicity in Antarctica and Greenland may be impeded by the ice
sheet presence above, supporting the theory of aseismicity during glacial loading and ice sheet
presence (Hamepl et al., 2010; Bungum et al., 2005; Stewart et al., 2000). Suber et al., (2000) Suber
and Molnia, (2004) and Larsen et al., (2005) supported this theory investigating seismic modulation
through glacial ice mass fluctuations, supported by seismic evidence between 1993 and 1995,

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indicating elevated seismicity in response to ice mass redistribution on a large scale. Results suggest
there is potential for elevated seismicity if future climate change continues and ice sheets decay.
Hampel et al., (2010) support the conclusion of future seismic response of ice mass loss in Greenland
and Antarctica through the reduced seismicity along the Teton fault during the Yellowstone Ice cap
existence and increased seismicity following its decay, taking the uniformitarian stance that
Greenland and Antarctica should behave in the same way.
Section 3: Eustatic Loading and Seismic Frequency
Following the LGM, sea level rose by ~120m between 20-7kya,(Smith et al., 2013; Fleming et al.,
1998) as a result of deglaciation, shown in figure 26.The Early Holocene is associated with the final
stage of deglaciation, resulting in rapid sea level rise ~60m, between 11.65-7Ka (Smith et al., 2011)
shown in figure 27. Sea level rise averaged between ca 10mm with maximums during the EHSLR of
ca12-13mm/yr (Bard et al, 2010; Smith et al, 2013).
Figure 26: Global Relative Sea Level rise following the LGM 20Kya to present; Fleming et al., (1998)

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Figure 27: Rapid Global Eustatic Sea Level Rise during the Holocene period 10Kya to present; Fleming et al., (1998)
The rate of sea level rise has not been constant, instead showing incremental, punctuated rises in SL
that Tornqvist and Hijma (2012) may result from meltwater, supporting Blanchon and Shaw, (1995)
and Bird et al (2010) who concluded that rapid rates of sea level rise may be controlled by large
subglacial and proglacial influxes of meltwater. Estimated times of meltwater pulses during SLR since
the LGM can be seen in figure 28.

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Figure 28: Graph indicating Relative sea level rise since the LGM, graph shows ~120m rise in Eustatic sea level, with
incremental jumps, attributed with possible meltwater pulses; Gornitz, (2007)
Smith et al., (2013) argue for a causal link between the rate of SLR during the EH, and increased
seismicity, based on SLR being a known cause of continental flexure and steepening (Bourcart, 1950)
however this has not been empirically confirmed to have impacted seismicity. Smith et al., (2013)
reaffirm the argument by Fairbridge, (1961) that hydro-isostatic effects by deglaciation result in
subsidence of the continental shelf and rebound of the adjacent crust, by supporting this with work
by mitrovica and petlier, (1991) who suggest inland meltwater migration to the continental shelf
increases loading. Furthermore modelling by Hutton et al., (2013) suggest ~30 % shelf steepening
occurred following the LGM, however this remains purely theoretical and only factors in SL loading,
potentially oversimplifying margin complexities, un-accounting for sedimentation and isostasy.
Smith et al., (2013) suggest that flexure probably resulted in increased seismicity, but fails to support
this with more than theoretical modelling and cause and effect theory.
Modells by luttrell and Sandwell, (2010) calculate ‘likely’ stress responses to oceanic loading since
the LGM, without palaeo-seismological data to support modelling. Luttrell and Sandwell, (2010)
conclude that the link between SLR and seismic induction remains unproven and unsubstantiated,

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but modelling confirms a potential for SLR to modulate seismic activity, however extent remains
unclear due to epistemic and aleatory uncertainties.
Smith et al., (2013) draw findings by Usman et al., (2011) who argue increased seismic frequency of
3-3.9Mw events along the Pakistani continental margin is a result of SLR. The paper merely presents
2 known increasing observable trends, with a possible cause and effect theory. However the authors
fail to statistically test this relationship, allowing for alternative conclusions as to cause and effect,
such as seismic cyclicities (McGuire, 2008; Bollinger and Costain, (1988). Furthermore the data set
spans 48yrs, indicating very little into true seismicity, indicating data bias, chosen in particular to
manipulate this apparent trend, in order to seek a theoretical link, with a known upward trend such
as SLR. Overall this suggests that in fact SLR may not be a causal mechanism and other factors may
be at play. In order to substantiate this ‘established’ link palaeo-seismological data would also be
required, to prove a long term trend exists, combining theoretical and empirical statistical studies to
remove uncertainties. Until this has been done this research should be disregarded as confirming a
link between SLR and increased seismicity. This furthermore enhances the fact that research used to
present the argument of SLR and increased seismicity by Smith et al., (2013) remains theoretical and
unsubstantiated.
Smith et al., (2013) further draw on Brothers et al., (2013) who identify columb stress increases of
>1Mpa across passive continental margin fault systems during the LP-EH transition, inferring a link
between SLR and seismicity. This supports earlier work by Brothers, (2011) which investigates the
effects of water loading on the San Andreas Fault, concluding that the combination of lake loading
elevated pore pressures and fault movement may be significant stressors to initiate fault rupture;
suggesting smaller hydrological loads may influence seismic frequency. Brothers et al., (2013)
supports this further by concluding that eustatic SLR may result in flexural stresses influential to
seismicity, results imply fault rupturing along passive margins between 15-8Kya was a likely
consequence of rapid SLR. This effectively supports the theoretical argument of Smith et al., (2013)
in that margin flexure from rapid eustatic rise may result in increased seismicity.
Overall Smith et al., (2013) present a compelling argument for rate of sea level rise and increased
seismicity, based on theoretical literature and modelling. However theoretical this remains,
requiring quantitative empirical studies to remove epistemic and aleatory uncertainties that

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surround the theory in order to substantiate. However challenges regarding the palaeo-
seismological record must be recognised, as a limitation to many studies. Furthermore the presence
of other influential processes during the EHSLR may also be seismically inducing such as PGR,
obscuring the reality of results. To overcome this further research into the effects of rapid sea level
rise on seismic frequency should be conducted away from glaciated and formerly glaciated margins
where PGR may be influential.
Section 4: Contemporary Climate Change and Seismic Activity
Overall based on the literature reviewed within this chapter it can be understood that PGR in
Fennoscandia did result in increased seismicity during peak deglaciation. The mechanism by which
PGR can influence Seismicity is understood and effectively modelled, further supported by palaeo-
seismological records. Therefore it is likely that to some extent seismic frequency may increase as a
result of continued ice mass loss at ice sheets, glaciers and ice caps. Currently further research is
required to effectively substantiate the cause and effect theory between SLR and increased
seismicity, as yet, theoretical studies and modelling have failed to provide comprehensive
understanding, in order to determine a future response. It could be concluded that there may to
some extent be potential for SLR to impact seismicity.
Chapter 6: The Impact of Climate Change on Submarine Failures
With increasing development along the continental shelves, slopes, margins and basins, submarine
failures are potentially hazardous to offshore marine installations and telecommunications.
Furthermore Submarine failures have the capacity to produce large devastating tsunami, hazardous
to coastal communities, such as the Papua New Guinea submarine landslide and tsunami in 1998,
(Tappin, 2001; 2008).
This chapter will discuss the methods by which submarine failures may have been influenced by
climate change in the past, followed by potential influences climate change may have on submarine
mass transport processes and determine whether future climate change may alter the frequency
and/or the intensity of these mass transport events.

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Section 1: Submarine Failures
Prior and Coleman, (1979) state that Submarine Landslides are the most common form of slope
instability, often greater in volume than terrestrial counterparts, figure 29, shows the four main
types of submarine mass failure.
Figure 29: Diagrams indicate the 4 main types of submarine instability; Prior and Coleman, (1979)
The causes of submarine landslides are indicated in figure 30, and the factors and processes
responsible for initiating Submarine Mass failures and Identified in figure 31.

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Figure 30: Identifies the causes of submarine landslides; Locat and Lee, (2002)
Figure 31: Diagrammatic representation of the factors and processes responsible for initiating Submarine Slope Failures;
Prior and Coleman, (1979)
Tappin, (2010) identified known locations of submarine mass failures, as shown in figure 32.

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Figure 32: Map showing the locations of known Submarine Mass Failures; Red dots indicate submarine failures known or
thought to have triggered tsunami, Yellow dots, Indicate failures along convergent margins, Green dots indicate
continental shelves, Blue dots indicate active river systems; Tappin, (2010)
Failure occurs when shear stress exceeds shear strength (Henkel, 1970). Figure 2, shows the known
locations of submarine failures, typically occurring most commonly in deltas, submarine canyon-fan
systems, fjords, continental slopes and volcanic flanks (Hampton et al., 1996; Lee, 2005, 2009;
Tappin, 2010). Controls on submarine slope stability have been identified by Lee, (2009) these
include i) sedimentation rates, volumes and types, ii) thickness of sediments, iii) changes in sea floor
condition affecting hydrate stability, v) seismicity and vi) alterations in ground water flow.
However Tappin, (2010) believes these controls to be in turn controlled by larger driving forces such
as glacial-deglacial cycles attributed to climate changes. Tappin, (2010) basis this notion on the idea
that environmental changes may result in changes in the factors that influences slope instability,
resulting in the slope sediment becoming ‘primed’ or ‘pre-conditioned’ for failure, which then only
requires a triggering mechanism or event to initiate the failure, such as an earthquake.

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Section 2: Submarine Failures and Past Climatic Changes
The Quaternary is a period renowned for exceptional climate changes, during the
Pleistocene/Holocene transitions from glacial to interglacial and the various stadial/interstadial
oscillations that occur. Urlaub et al., (2013) compiled a data set of large global submarine landslides,
with known ages and volumes from the Quaternary period, shown in figure 33.
Figure 33: Locations of Submarine Landslides; Different symbols represent differing depositional systems (dots: glaciated
regions, rectangles: sediment-starved margins, triangles: river fan systems,); Urlaub et al., (2013). The map indicates the
majority of known submarine landslides occur in the northern latitudes; however this could be due to data biases.
It has been suggested by a variety of authors for many years now that climate change maybe
capable of influencing the occurrence of submarine slides through, glacial/interglacial sedimentation
rates, sea level rise, glacio-hydro-isostacy and increased seismic triggering mechanisms. This chapter
will therefore discuss the mechanisms by which climate change may have the capacity to alter
submarine mass transport processes that may trigger submarine failures.

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Section 3: Rates of Sedimentation and Slope Stability
Changes in the parameters that affect slope stability identified by Lee, (2009) can be a consequence
of glacial-deglacial cycles as a result of changes in the sediment regime, influencing pore pressures
within the slope sediments.
During glacial times, rapid thick sedimentation occurs, resulting in increasing pore pressures
(Kvalstad et al., 2005; Tappin, 2010; Smith et al., 2011; Stigall, 2009; Dugan and Stigall, 2009; Laberg
et al., 2006). Interglacials result in the deposition of fine grained sediments that are susceptible to
failure (Tappin, 2010). This has been linked as the ‘priming’ and ‘preconditioning’ mechanism that
may result in failure once triggered, by an event such as an earthquake through isostatic rebound or
gas hydrate dissociation (Kvalstad et al., 2005; Tappin, 2010; Smith et al., 2011; Stigall, 2009; Dugan
and Stigall, 2009; Laberg et al., 2006; Liggins et al., 2010; Maslin et al., 2010).
Rates of sedimentation are greater during glacial periods than interglacial periods (Tappin, 2010),
this alters the sediment regime of submarine slopes, leading to excess pore pressures that result in
sediment preconditioning (Tappin, 2010) making the slopes liable to failure through triggering
mechanisms. This process has been used to explain the Storegga Submarine Landslide Event.
Gacio-isostastic-seismicity; as previously discussed in chapter 5, post glacial rebound (PGR) occurs as
a result of glacial unloading resulting in the uplift of the crust that lay beneath the former ice mass,
this can lead to elevated slip rates along tectonic faults (Hampel et al., 2010), resulting in increased
seismic frequency. Chapter 5 also discussed the relationship between eustatic loading from rapid sea
level rise on seismicity, concluding there could be a link, but at this stage it remains theoretical.
Chapter 5 concluded that PGR has been a likely control on observed elevated seismicity in formerly
glaciated areas and furthermore there may be a link between the rates of sea level rise on seismic
frequency.
It is believed that seismicity may have been the triggering mechanism for the Storegga submarine
mass failure that occurred offshore mid Norway. Tappin, (2010) believes this to be the result of PGR

55 | P a g e
whilst Smith et al., (2013) believe it to be the result of eustatic sea level rise increasing potential
seismicity.
Section 4: The Holocene Storegga Slide
The Holocene Storegga slide is a large submarine landslide identified on the mid-Norwegian
continental margin. The slide is one of eight submarine slides identified within the Storegga slide
complex (Solheim et al., 2005). The Norwegian continental margin is prone to large scale sliding due
to its structural setting and sedimentary deposition linked to changes in the sediment regime
through glacial/interglacial cycles, with a slide recurrence interval suggested by Solheim et al., (2005)
of approximately 1/100ky following glacial/interglacial sequences. Slide characteristics and
morphologies are similar as discussed by Solheim et al., (2005), further strengthening the
glacial/interglacial cyclic control on submarine activity upon this margin.
The Holocene Storegga slide is the most fully understood, research undertaken to understand the
geohazards of the area as a result of the Ormen-Lange gas field proposals which lead to significant
multi-disciplinary research and advancements in submarine slope science (Solheim et al., 2005).
Solheim et al., (2005) explain the Storegga slide as being a translational slide, dated by Bondevik et
al., (2012) to between 8120-8175ky, using green mosses preserved in the tsunami deposits. Dating
places the slide around the same time as the 8.2ka cold event. One conclusion that could be drawn is
that like the 8.2ka event, Storegga was also a response to the Lake Aggasiz-Ojibway (LAO) outburst.
4.1: The 8.2Ka Event, LAO and Storegga
As discussed in Chapter 3, the 8.2ka event 8.15-8.25ka BP, is believed to have been triggered by the
outburst of LAO 8.18-8.31ka BP, (Li et al., 2012; Tornqvist and Hijma, 2012; Smith et al., 2013; Smith
et al., 2011; Barber et al., 1999; Alley et al., 2003; Alley and Augustsdottir, 2005; Lajeunesse and St-
Onge, 2008., Cheng et al., 2009; Teller et al., 2002) outflow was a result of deglaciation of the
Laurentide ice sheet during the EHSLR warm period.

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Smith et al., (2011) review evidence for the cause of the 8.2ka event, expanding on the work of
Barber et al., (1999) who suggested the event had been triggered by the LAO outflow. Smith et al.,
(2011) argues causal link through the age proximity of the two events when reviewing the time
evidence for both events, showing that outflow is a likely causal triggering mechanism for the 8.2ka
event. This is later expanded in Smith et al., (2013) to incorporate the Storegga submarine landslide
in to this chain of events, citing the rapid sea level jump associated with the drainage of LAO, and the
8.2ka event as a possible triggering mechanism.
Smith et al., (2013) argue this case with Storegga dated to 8120-8175ky BP (Bondevik et al., 2012)
and LAO drainage at 8.18-8.31ka BP, suggesting that the age proximity of the events may indicate a
cause and effect relationship through rapid sea level rise and overburdening of the submarine
sediments.
Smith et al., (2013) not only argue that the LAO outflow inferred a dramatic oceanic and climatic
response triggering the 8.2ka event, but may have potentially elicited a geospheric response through
the Storegga submarine failure. This is due to the fact the LAO drainage resulted in global eustatic
rise of ~1.11-4.19m based on an outflow volume of ~ 40,000-151,000km3 (Clarke et al., 2004; Lewis
et al., 2012) this rapid Eustatic rise may have triggered Storegga through overburdening and pore
pressurization of the unconsolidated glacial deposits through eustatic rise. This argument for cause
and effect can be observed in figure 34.
Figure 34: Time graph, showing age proximity of events; LAO discharge, Holocene Storegga slide and Storegga slide
tsunami; Smith et al., (2013)

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This hypothesis shared by Trincardi et al., (2003) who identify a possible relationship between the
rate of sea level rise and submarine failure. Trincardi et al., (2003) discuss two slides identified along
the Tyrrhenian margin, dated to 13-14kya, the authors note that this corresponds with a known
rapid rise in sea level as a result of meltwater pulse 1A (MWP1A). The authors also argue for age
proximity as a causal mechanism, suggesting like smith et al., (2013) that rapid loading could be
attributed to failure.
Trincardi et al., (2003) also suggest further investigation into the BIG’95 debris flow, as the timing of
this event also corresponds with the suspected timing of meltwater pulse (MWP1B) as shown in
figure 35. However Canals et al., (2004) conclude that although sedimentation and SLR would have
been important preconditioning mechanisms the most likely trigger was seismic based on
earthquake return intervals of mw4-5/5yrs.
Figure 35: Graph indicating the possible relationship between meltwater pulses, sea level rise and submarine landslides,
through age proximity of events. Big ’95 debris flow corresponds with timing of MWP 1B; And the Tyrrhenian slides
(Paola & Licosa) correspond with MSP 1A; Trincardi et al., (2003)
Section 5: Sea Level Rise and Submarine Failures
The idea that sea level rise may trigger submarine failures, is supported by a range of authors;
Garziglia et al., (2003) theorise that the S16 event along the Western Nile Margin, occurred during
the Quaternary around the time of high rates of sedimentation and rapid sea level rise, inferring an

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age proximity relationship for a triggering mechanism. Georgiopoulou et al., (2010) also suggest a
link between increased sedimentation rates, followed by sea level rise, causing excess pore
pressures as a trigger for the Saharan slope failure, supported by evidence from other slides found
along the African Continental Margin.
This is also supported by Wien et al., (2006) who suggest that turbidite deposition the Submarine
Canyon off NW Africa is heavily associated with sea level changes during glacial/interglacial
transitions, arguing that both sea level fall and sea level rise as potential causes for slope
instabilities. This was further developed by Wien et al., (2007) who concluded that the Mauretania
slide complex can be linked to Quaternary sea level rise. This is in agreement with the conclusions of
Antobreh and Krastel, (2007) whom identified sediment preconditioning and excess pore pressures
to have primed the slope. Seismic reflection data indicated that a likely trigger would be an
earthquake. However as yet no such seismic trigger has been identified, inferring SLR on its own may
have created substantial pore pressures to exceed strength and initiate failure. This is in agreement
with Prior and Suhyada, (1979) who suggested that when large pore water pressures exist within
sediments they alone may overcome shear strength through gravitational forces, as previously
discussed by Terzaghi, (1956).
However, Stigall and Dugan, (2010) believe that the combination of increased pore pressures as a
preconditioning mechanism and seismicity as a trigger is required, in agreement with Tappin, (2010)
and Smith et al., (2013). However using the available global submarine landslide database, Urlaub et
al., (2013) find no statistical significance to a relationship between SLR and Submarine landslide
occurrence. However the analysis uses global sea level curves as opposed to local sea level curves,
oversimplifying the system and introducing aleatory uncertainties, to a topic where large epistemic
uncertainties already exist with regards to data collection.
5.2: Eustatic Induced Seismicity as a triggering mechanism
Smith et al., (2013) further suggest that the rapid jump in sea level as a result of the freshwater
outflow from LAO may have been influential in triggering the earthquake which is thought to have
initiated the Storegga failure. This opinion is contrasted by Trincardi et al., (2003) who believe that
the rapid sea level rise and overburdening may have been enough alone to have triggered the two

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slides along the Tyrrhenian margin, whilst noting that a tectonic trigger independent of eustatic
pressure may have triggered the failures.
Smith et al., (2013) have linked the earthquake triggering mechanism of Storegga to increased
seismicity as a result of sea level rise, this is in contrast to the conclusion of Tappin, (2010) who
believes the earthquake trigger to be the result of increased seismicity through PGR, supported by
Brothers et al., (2013) who state based on work Bungum et al., (2005) Wu and Johnston, (2000) and
Klemann and Wolf, (1998) that; crustal stresses as a result of sea level rise in high latitudes adjacent
to glacial masses are likely to be of less significance than those attributed to PGR and Isostatic uplift.
This therefore means that although the theoretical link between rate of sea level rise and increased
seismicity has been made by Smith et al., (2013) as yet it remains to be unproven as a significant
influence on seismicity, whilst the link between PGR and seismicity in Norway has been identified,
indicating that the most likely trigger of the Storegga submarine failure was PG seismicity as
concluded by Tappin, (2010).
Furthermore as yet no quantitative empirical data has been used to support the notion of sea level
rise inducing seismicity, as previously discussed in chapter 2, therefore further research would be
required to correspond modelling and palaeo-siesmicity along the Norwegian continental margin to
determine seismic occurrence and likely causes. However, it is unlikely that a complete data set
could be identified, in an area which has experienced sliding, postglacial rebound as well as marine
environmental changes that may alter the deposits.
However, it should be noted that whether or not a link is confirmed between sea level rise and
seismicity, earthquakes are a known triggering mechanism for submarine failures (Tappin, 2010;
Tappin et al., 1998) and that the Storegga slide was most likely initiated by an earthquake source.
Furthermore, there remains a large amount of uncertainty into palaeo-events, that require more
research in order to remove there epistemic uncertainties, in order to accurately conclude the cause
and effect relationships between the ‘ocean-cryosphere-atmosphere’ and geosphere in order to
ascertain the likelihood of increased submarine activity in the future.

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Section 6: Contemporary Climate Change and Submarine Failures
This section has demonstrated the link between glacial/deglacial cycles as preconditioning
mechanisms for slope instability. This chapter has also demonstrated the link between earthquakes
and submarine failures concluding that they are a viable triggering mechanism for initiating
submarine failure. This chapter discussed the link between sea level rise and seismicity as a trigger
for submarine slope failure and finds that as yet there is insufficient evidence to demonstrate SL
induced seismicity as a triggering mechanism for initiating failure; however it may be possible but
unlikely particularly in the case of the Holocene Storegga Slide.
Overall this chapter concludes that further deglaciation due to current climate change may result in
increased seismicity which could trigger future submarine failures, which may potentially generate
tsunami’s similar to that of the Holocene Storegga submarine landslide and Tsunami.
Chapter 7: Final Discussion and Concluding Remarks
Section 1: Final Discussion
Climate change presents large amounts of uncertainty, when predicting and modelling future
scenarios. However it is almost certain that warming as a result of anthropogenic activity has been
observed and can be expected to continue, resulting in 3 key impacts; temperature increase,
continued ice mass wasting and continued sea level rise. According to McGuire, (2010) this should
elicit a response from the geosphere.
Based on an analysis, evaluation and discussion of the literature this paper concludes that;
 Deglaciation associated with climate change has previously increased volcanism therefore
there is a link between climate change and volcanic activity.

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