Identifying Tsunami Risk in South China Sea

Identifying Tsunami Risk in South China Sea Chiu Hon Chim (chius@hku.hk) Department of Earth Sciences The University of Hong Kong

Outline ,[object Object],[object Object]

Tsunami Generation Sources (Switzer, 2006)

Tsunami Generating Earthquakes ,[object Object],[object Object],[object Object]

05/26/09 ,[object Object],Tsunami Generating Earthquakes

05/26/09 D istant Earthquakes ,[object Object],[object Object],HKO A bout 0.1m 6.7 C hile 1985.03 N one reported 9.5 S umatra 2004.12 0.6 m 8.5 C hile 1960.05 0.15 m 8.2 K amchatka 1952.11 M ax Amplitude Recorded in HK E arthquake Magnitude O rigin D ate

05/26/09 Regional Earthquakes ,[object Object],[object Object],Hong Kong Subduction Zone Strike-slip Faults Horst and Graben Continental Shelf

05/26/09 M anila Trench ,[object Object],[object Object],7mm yr -1

05/26/09 Regional Earthquakes ,[object Object],[object Object],[object Object],H owever, the only documented tsunami (0.28m) generated regionally occur as a M5.4 earthquake ,[object Object],[object Object]

05/26/09 Tidal Record: 24 June 1988 Time of Earthquake HKO

05/26/09 However … ,[object Object],[object Object],[object Object],[object Object]

05/26/09 Tsunami Generating Earthquakes ,[object Object]

05/26/09 Earthquake: Local ,[object Object],[object Object],[object Object],[object Object],HK

05/26/09 What we know ,[object Object],[object Object],[object Object],[object Object],[object Object]

05/26/09 T he 3 Large Earthquakes near HK 1918.02.13 M7.3 1604.12.29 M7 1994.09.16 M7.3 HKO 1988.06.24 M5.4 When did it last move? HKO HK

Summary ,[object Object],[object Object],[object Object],[object Object]

05/26/09 Tsunami Generation Sources (Switzer, 2006)

05/26/09 V olcanism in the Past ,[object Object],[object Object],[object Object],Q = Q uaternary = Past 1.8 million years Large volume of lava release could trigger tsunami HK E Q E E E N E Q Q Q N Q N E Q E E E N E Q Q Q N Q N

05/26/09 Any future volcanism? ,[object Object],[object Object],[object Object],Heat Flow Distribution in South China Sea, After Lau (1994) Geothermal Heat Flux 20 40 60 80 100 120 140 HK

05/26/09 Extensional Basin S ubmarine slumping: River sediments “falls” from here to here HK

05/26/09 Submarine Slides / Slumps ,[object Object],[object Object],[object Object],[object Object],[object Object]

05/26/09 Bolide Impact – More often than you think? ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

05/26/09 How likely is it? R eturn Period 10 7 10 2 10 2 10 4 S ize of Bolide, diameter in m E g. Mega-tsunami, SE Australia, ~0.5ka E g. Global tsunami, Chicxulub, Bay of Mexico, 65Ma (R ickman, 2005) Millions of Years Centuries

05/26/09 The Earth ,[object Object],[object Object],[object Object],[object Object],[object Object],www.ngdc.noaa.gov/mgg/fliers/95mgg01.html

Tsunami Risk in HK ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Tsunami Characteristics ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

D istant Earthquakes T ravel time graphs Speed = gravity / depth Nearshore effect ignored HKO

Regional Earthquakes ,[object Object],[object Object],[object Object]

Based on Imamura (1997) ,[object Object],[object Object],[object Object]

Parameter used ,[object Object],[object Object],[object Object],[object Object]

Inundation Results: HKO ,[object Object],[object Object],[object Object],[object Object],[object Object],HKO Tidal Range Runup

Regional & Local Earthquakes ,[object Object],[object Object],[object Object],[object Object]

Modelling Tsunami in South China Sea - General Modelling Techniques ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Identifying Tsunami Risk in South China Sea

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