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SUMMARY:Simulation of seismic wave propagation through geometrically compl
 ex basins - the Dead Sea basin - Michael Tserarsky\, Ben Gurion Univeristy
 \, Israel
DTSTART:20110920T150000Z
DTEND:20110920T160000Z
UID:TALK33032@talks.cam.ac.uk
CONTACT:Alexandra Turchyn
DESCRIPTION:The Dead Sea Transform (DST) is the source for some of the lar
 gest earthquakes in the Eastern Mediterranean\, including the 1927 MW 6.2 
 Jericho earthquake and the 1995 MW 7.2 Gulf of Aqaba earthquake. The seism
 ic hazard presented by the DST threatens the Israeli\, Palestinian and Jor
 danian populations alike. Several deep and structurally complex sedimentar
 y basins are associated with the DST. These basins are up to 10 km deep an
 d typically bounded by active fault zones.\n\nThe low seismicity rate of t
 he DST combined with a sparse seismic network in Israel that provides poor
  coverage of sedimentary basins\, results in a critical knowledge gap. It 
 is therefore necessary to complement the limited instrumental data with sy
 nthetic data based on computational modeling\, in order to study the effec
 ts of earthquake ground motion in these sedimentary basins.\n\nIn this res
 earch we performed a ground motion analysis in the Dead Sea Basin (DSB) us
 ing a finite-difference code capable of simulating seismic wave propagatio
 n in a 3-D heterogeneous earth. Two 2-D cross-sections transecting the DSB
  were compiled based on currently available geological and geophysical dat
 a and were used for wave propagation simulations. Results indicate a compl
 ex pattern of ground motion amplification affected by the geometric featur
 es in the basin.\n\nTo distinguish between the individual contributions of
  each geometrical feature in the basin\, we developed a semi-quantitative 
 decomposition approach. This approach enabled us to interpret the DSB resu
 lts as follows: (a) Ground motion           amplification as a result of r
 esonance and anelastic effects\, occurs basin-wide due to a high impedance
  contrast at the base of the uppermost layer. (b) Steep faults generate a 
 strong edge-effect that further amplifies ground motions. (c) Sub-basins c
 ause geometrical focusing that under certain circumstances significantly a
 mplifies ground motions. (d) Salt diapirs diverge seismic energy and cause
  a decrease in ground motion amplitude. 
LOCATION:Harker 1 seminar room\, Department of Earth Sciences
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