HR: 0830h
AN: T51D-0190    [PDF]
TI: Regional Moment Deficits in Southern California
AU: * Meade, B J
EM: meade@mit.edu
AF: Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 54-610 77 Massachusetts Ave., Cambridge, MA 02139 United States
AU: Hager, B H
EM: bhhager@mit.edu
AF: Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 54-610 77 Massachusetts Ave., Cambridge, MA 02139 United States
AB: We present a novel method for detecting regions of seismic moment deficit. These are areas where the moment release associated with large historical earthquakes does not balance the moment accumulation rate observed today. The total deformation field for the last two centuries is calculated by converting estimated focal mechanisms to rupture lengths, depths and displacements using empirical scaling relationships. We estimate the total amount of accumulated surface deformation over the same time period based on estimates of fault slip rates from a block model. These slip rates are then scaled to displacements by multiplying by the time since the start of the earthquake catalog ($\sim$200 years). Total surface displacements for both cases are calculated with an elastic dislocation model. The residual (accumulation minus release) deformation field allows us to clearly identify regions of seismic moment deficit. Finally, the residual displacements in each zone of moment deficit are inverted for the best fitting single event source. We find three regions of significant moment deficit in southern California: the Southern San Andreas and San Jacinto Faults, the gap between the 1872 Owens Valley and 1992 Landers earthquakes, and the offshore faults to the south of Los Angeles.
DE: 7223 Seismic hazard assessment and prediction
DE: 7230 Seismicity and seismotectonics
DE: 8123 Dynamics, seismotectonics
DE: 8150 Plate boundary--general (3040)
SC: Tectonophysics [T]
MN: 2003 Fall Meeting