Directivity analysis of the Deep Bolivian Earthquake of June 9, 1994



The June 9, 1994 deep Bolivian earthquake (MW = 8.3, d = 636 km) occurred on a nearly horizontal rupture plane with an approximate area of 2000 km². The rupture plane is constrained by directivity analysis of the P wave displacement pulses recorded at local, regional, and teleseismic distances. The fact that there are local recordings of the displacement provides a strong constraint on the vertical extent of faulting, which is less than ∼10 km. The moment release had at least four distinct episodes, or subevents. The best overall explanation for the subevents is rupture which initiates on the western margin of the fault plane, propagates to the east, and then continues bilaterally along a 350° azimuth, with most of the moment release occurring to the north. The apparent rupture velocity between subevents is very low, approximately 1–2 km/s.