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Pathway 4 (shown
below in red) comprises a variety of important seismological inverse
problems, which include using the ground motions observed in real
earthquakes to image the fault rupture process (source inversion)
and the 3D variations in seismic wave velocities and attenuation
factors (structural inversion). At present, these inversions are
usually done using 1D propagation models (e.g., for source imaging
and surface-wave inversions) or simplified physics, such as asymptotic
ray theory (e.g., for source location and travel-time tomography).
Full use of broadband seismographic recordings in these inverse
problems is currently limited by the difficulties in managing the
forward calculations corresponding to Pathways 2 and 3. Furthermore,
with very few exceptions, inverse problems considered to date explain
ground motions using kinematic modeling, wherein the distribution
of displacements or stress drops on a prescribed fault surface is
related linearly to seismograms through a wave propagation model.
Dynamic inversions in which observed seismograms are assimilated
into a spontaneous fault rupture model with self-organizing geometry
present seismological and computational problems that will take
many years to solve, although initial efforts show considerable
promise.
SCEC/CME Computational
Pathway Diagram:
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