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An example of science aided by
cyberinfrastructure - Geodynamics of
the Himalaya
Chris Andronicos
Institute for the Study of the Continents, Cornell University
and
Aaron A. Velasco,
Jose M. Hurtado
Department of Geological Sciences
University of Texas at El Paso
Can you do science with what is
already out there?
The Internet provides access to a vast
amount of data in various subjects but…
The data is usually not peer reviewed
Some available information is of dubious
nature
Data is often available in formats which are
difficult to utilize for the problem of interest
Data may be out of date
Datasets and Programs Used
Harvard Centroid Moment Tensor
World Stress Map
Shuttle Radar Topography Mission
Generic Mapping Tools
Commercial software and publicly
unavailable data
Motivated by results of computer
generated geodynamic models
World Stress Map
Extensive Database of on the state of
stress in the earth from geological and
geophysical data
http://www-wsm.physik.unikarlsruhe.de/pub/home/index_noflash.html
Harvard Centroid Moment Tensor
Catalogue
Extensive global database of focal
mechanisms with magnitude greater than
5.5 since 1977
Easy search functionality
Shuttle Radar Topography Mission
(SRTM)
Provides elevation data at 30 m resolution
for much of the earth
Easy to produce digital elevation models
for large regions
http://srtm.usgs.gov/
Outline
Earthquakes and Strain Partitioning
Depth Distribution of Earthquakes
Earthquakes and topography
Conclusions
Earthquake Kinematics
A focal mechanism for an earthquake
gives the orientation of the greatest
compression (P) and least compression
(T) axis
Based on the orientations of the P and T
axis we can divide the earthquakes into
kinematic types
Data source: Harvard Centroid Moment
Tensor catalogue and World Stress Map
Kinematic Types
P plunge
T plunge
Strike Slip
<30
<30
Thrust
<30
>60
Normal
>60
<30
Transpression
30 to 60
30 to 60
P<T
Transtension
30 to 60
30 to 60
P>T
Strike-Slip Fault P-axis
Thrust Fault P-axis
Transpressive Fault P-axis
Normal Fault T-axis
Transtensive Fault P-axis
Kinematic Domains
30
29
44
10
23
46
Depth Distribution of Earthquakes
Dataset developed for CTBT verification
(Bombs)
Only events that included a depth phase
(pP or sP) were included
Data set includes 26 “ground truth events”
developed by bomb monitoring community
Possible to map brittle & ductile strain
Work by Steck, Velasco and others, 1997
Beaumont et al., Nature
Relief Map
Data Source-SRTM
A Possible Explanation
Conclusions
Major faults in Tibet bound regions of
transtension that are likely underlain by a fluid
lower crust which is flowing eastward
Thrust events are correlated with the range
margins, normal faults are correlated with high
flat topography
This reflects critical taper wedge mechanics
coupled with ductile lower crustal flow
Publicly available datasets allow examination of
large scale problems in the Earth Sciences