Plate Boundary Structure Along the San Andreas Fault


Author: Furlong, Kevin


The San Andreas plate boundary through California represents perhaps the best studied major fault zone in the world. Even with the large amount of geological and geophysical data which have been collected, much is still unknown about the causes, timing, and triggering of major earthquakes along the boundary. In our research at Penn State, we are focusing on improving our picture of the three- dimensional structure of the crust and lithosphere along the Pacific-North America plate boundary. We have active research projects imaging the 3-D crustal structure in the San Francisco Bay region using seismic tomography (right), evaluating the consequences of a complex plate boundary structure for the region (below), and studying the consequences of large earthquakes in the region enhancing the potential for other large earthquakes as stress is redistributed. Much of the work in the San Francisco Bay region is part of the Bay Area Seismic Imaging eXperiment (BASIX) which is a multi-institution project aimed at developing an improved picture of the crustal structure and fault zone interaction.

Penn State Geodynamics research has led to a new model of plate boundary structure in the San Francisco Bay region. By combining numerical modeling of plate boundary evolution with observations of crustal deformation, seismic velocity structure and earthquake patterns. The model shown on the left which includes a lower crustal connection among the major faults in the region was developed. Results from the BASIX project validate this model. Now we are investigating the consequences of this plate boundary structure for the development of San Francisco Bay, the potential for earthquakes on major faults to be coupled, and the evolution of the continental margin.


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