9526810 Zhao, Dapeng This research is to investigate the detailed 3-D crustal and upper mantle structure and its relationship to the seismotectonics of the Kobe, Japan, region. Data from the January 17, 1995 Kobe earthquake and its aftershocks will be used. Preliminary results show a low velocity zone beneath the hypocenter of the earthquake and one of the goals is to investigate Poisson's Ratio in this zone to test a model of fluid triggering of the main shock. Deeper upper mantle structure will also be determined to see how deep the Philippine Sea plate is penetrating beneath this region. The results will be important for understanding the triggering mechanism and rupture process of large earthquakes, and provide a physical framework for understanding the relationship between crustal earthquake activity, lateral variation of the structure, and subduction and magmatic processes in the deeper areas. A better understanding of these features is important for the log-term seismic hazard assessment in this region, and provide useful references to other seismically active regions. This research is a component of the National Earthquake Hazard Reduction Program. *** ??
