What is SRTM?
Definitions of SRTM on the Web:
•The Shuttle Radar Topography Mission (SRTM) is an international
research effort that obtained digital elevation models on a near-
global scale from ... en.wikipedia.org/wiki/SRTM
•A NASA Space Shuttle mission that used C-band and X-band
interferometric synthetic aperture radars (IFSARs) to acquire
topographic data over 80 ...
earthobservatory.nasa.gov/Library/glossary.php3

Where can you get it?

Different formats available

Another site for Landsat & SRTM

How can you use SRTM?
•Mapping current geomorphology
•Mapping lineaments and other structural features
•Landsat shows surface variations while SRTM has a
penetration depth – ie reveals subsurface
information useful for structural interpretations
•Spatial Analyst (ESRI) can be used to creat
hillshades of the data as shown on following slides

SRTM hillshaded view Cape Fold Belt near Montague

SRTM hillshaded view and modified colour ramp

SRTM hillshaded view and modified colour ramp

Paleochannels
interpreted from
aeromagnetics data
SRTM can be used in
combination with other
geophysical datasets
to reveal variations in
geological patterns
/ processes with time.
An example of this is
detecting changes in
drainage channel patterns
with time – which is NB
When considering alluvial
diamonds.

Older paleochannel course (red
vectors from aeromagentics data)
More recent paleochannel
course
(from SRTM greyscale
image)
Comparing recent drainage with
paleodrainage from geophysics data

Placing drilled samples in the context of channel migration

SRTM imagery can also be used to create flow direction
maps based on the associated DEM data
Hillshaded
SRTM data
overlain by
extracted
streams

SRTM imagery can also be used to create flow direction
maps based on the associated DEM data
Extracted
streams

Regional
aeromagnetics
data for
Southern Africa
– further basis
for aiding
structural
interpretations

Regional aeromagnetics at 50 m – as tiffs for countries
Tracing
units of
interest

Regional aeromagnetic data as grey scale

Combining
aeromagnetic
data with
geology for
exploration

A closer look at using multiple datasets for exploration
•Geological problems are often regional in nature
There are many gaps in detailed geological mapping
Remote sensing techniques provide a way to bridge
these gaps
GIS facilitates this process immensely

A closer look at using multiple datasets for exploration
In the following example we see how regional
aeromagnetic data is used in a regional study to trace
the trail of a geological unit of interest.
Data from historical studies, digital geological data,
structural and other geophysical data sets are all
analyzed together in an attempt to define the unit
across country boundaries.

Structural and aeromagnetic data comparisons.

Structural and aeromagnetic gradient data

Comparing lithological datasets for different countries
A
B

Structural and aeromagnetic dataset comparisons

Feature definition
Is the data good
enough to resolve the
feature of interest?
Buffers around known
unit trend compared to
aeromagnetics data
image

Extrapolating the buffer zone across several images

Mapping trends where the trace of the unit is lost

Mapping trends where the trace of the unit is lost

Filling the data gaps

Can one link the trends back to the most likely
continuation of the unit?

More on Aeromagnetic data
•Ring features are sometimes viewed on
aeromagnetic / Landsat datasets
•These maybe associated with radial dykes /
intrusives or impact craters
•Both provide an potential area of interest for
exploration
•In the following example we see how such
features may appear on the imagery

Aeromagnetic data
color ramped
Ring features – radial
dykes / intrusives or
impact craters?

Through
customized image
processing
additional ring
features are visible
(Impact crater
Research Group,
Wits, 2008)
MATLAB processed image
georeferenced in ArcMap

MATLAB processed image 3D view

MATLAB processed image – impact crater modeling