This research involves the development of intermediate- and near-field terms for large earthquake ruptures and application of this to the 1994 deep great Bolivian earthquake (magnitude 8.3, 636-km depth, 9 June 1994). Modern broadband seismic instrumentation has revolutionized seismology and allowed the retrieval of information in almost any frequency band of seismic interest. Through serendipity, a PASSCAL portable broadband seismic experiment "captured" the static displacement just above the earthquake as well as very long period waves between the P and S waves. These signals may be interpreted as the intermediate- and near-field terms of the displacement field associated with a shear dislocation. Since the1994 event, more than 16 additional deep earthquakes have been identified which produced similar intermediate- and near-field terms. Since these terms depend on the temporal evolution of the seismic moment rather than the moment rate (as is observed in far-field seismic signals), modeling these terms could provide new insights into the mechanics of earthquakes. This research is a component of the National Earthquake Hazard Reduction Program.
