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NSF Funds Earthquake Simulations

Solving the Inverse Problem.
Solving the Inverse Problem.
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Solving the Inverse Problem
As a first test for the extreme computational challenge of the inverse problem, the Quake Group chose a 2D shear-wave velocity distribution (top) in a 35 km x 20 km cross-section of the LA Basin model as a synthetic target. Starting with ground-motion measurements on the surface (64 points distributed evenly), the inverse algorithm (with a 257 x 257 grid) arrived at material properties for the cross-section that gave a velocity distribution (bottom) in close match to the target.

PITTSBURGH, October 10, 2003 — The Quake Group, a large collaborative research team led by Jacobo Bielak, Omar Ghattas and David O'Hallaron of Carnegie Mellon University, has received $1.9 million from the National Science Foundation to continue its work in high-fidelity earthquake modeling. This grant, through the NSF Information Technology Research program, will support the Quake Group and PSC collaborators in developing a 3D seismic "inverse" model that can determine subsurface geology by working backward from seismic measurements on the surface.

In recent computations with LeMieux, PSC's terascale system, the Quake Group simulated the 1994 Northridge earthquake at double the frequency of prior earthquake models. For work on the inverse problem, Ghattas and his former students Volkan Akcelik and George Biros won the Best Technical Paper Award last year at Supercomputing 2002. Their inverse wave-propagation algorithm exploits parallel systems like LeMieux, which they recently used to solve a test case in two dimensions, demonstrating the viability of their inverse approach.

In future work with LeMieux, they plan to extend the inverse simulations to 3D. "The inverse problem is orders of magnitude more difficult than the forward problem," says Ghattas. "Large parallel systems and powerful algorithms are crucial."

The NSF Award abstract:

More information on recent Quake Group simulations of the 1994 Northridge quake:

Quake Group home page:

The Pittsburgh Supercomputing Center is a joint effort of Carnegie Mellon University and the University of Pittsburgh together with the Westinghouse Electric Company. It was established in 1986 and is supported by several federal agencies, the Commonwealth of Pennsylvania and private industry.


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Michael Schneider
Pittsburgh Supercomputing Center

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