[SIO GP Seminars] Shamita Das, Oxford University, U.K.

[Matt Wei]

Please join us today, for the last GP Seminar of this quarter.

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FRIDAY, Mar. 23, 3:00 PM
(refreshments served at 2:45 PM)
Munk Conference Room

Shamita Das,
Oxford University, U.K.

Effect of the subducting seafloor topography on the
rupture characteristics of great subduction zone earthquakes

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Abstract:

With the improvement in both the seismological data, sea-floor
topography and gravity data, we are now starting to
see the effect of sea floor topography on the rupture
process of great subduction
earthquakes. Subducting seamounts were first suspected
to be affecting the
rupture process of a great earthquake in the 1986
Mw 8.0 Andreanof Islands earthquake, where
large slip was seen in isolated round
patches in the direction of the plate subduction
(Das and Kostrov, JGR, 1990). Improvements in bathymetric
data since then
seem to confirm this. A more recent example
is the 2001 Mw 8.4 Peru earthquake, where a
subducting seamount stalled the rupture process
for ~30s, and then broke, thereby resulting in the
third largest earthquake worldwide since
the 1960's (Robinson et al., Science, 2006). Other
examples will be shown. An important question
is how much of a seamount still remains after
it is subducted to be able to
affect the earthquake rupture on the
subduction plane. Recent high quality
bathymetric and seismic surveys
from the Middle America trench, shows
both the trauma on the hanging wall
associated with the subduction of a seamount,
as well as large, clear, subducted seamounts after
subduction (Von Heune et al., Tectonics, 2000).
We believe that such features are, in fact,
common and will be identified with increasing
frequency with improving surveys, and hope
that our study will encourage this search for
other major subduction zones around the world.

Have a good day.

Matt

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Meng Wei ( Matt )
Institute of Geophysics and Planetary Physics
Scripps Institution of Oceanography
University of California, San Diego
La Jolla, CA 92093-0225
mwei at ucsd.edu
(858) 822-4347
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