San Fernando Valley Simulation

The top left figure (based on a model developed by Magistrale, McLaughlin, and Day at SDSU) depicts the variations in shear wave velocity near the free surface in the San Fernando Basin. The bottom left figure shows an unstructured mesh constructed so that it employs smaller elements in softer soils, where seismic wavelengths are small. The mesh is partitioned for 64 processors. The figure on the right displays the maximum surface ground motion (divided by the free field motion on rock) experienced during a simulated seismic event.

The simulation results indicate that the magnitude of the shaking in the basin is up to nine times larger than that of the rock, suggesting substantially greater damage in these regions. The ground motion was computed on the Cray T3D at the Pittsburgh Supercomputing Center using a mesh of 14 million tetrahedra and 2.5 million nodes.