HR: 08:15h
AN: S41A-02    [PDF]
TI: Comparison of co-seismic and post-seismic slip of large earthquakes in southern Peru and northern Chile
AU: * Pritchard, M E
EM: matt@gps.caltech.edu
AF: Caltech, 1200 E. California Blvd. 252-21, Pasadena, CA 91125 United States
AU: Ji, C
EM: jichen@gps.caltech.edu
AF: Caltech, 1200 E. California Blvd. 252-21, Pasadena, CA 91125 United States
AU: Simons, M
EM: simons@caltech.edu
AF: Caltech, 1200 E. California Blvd. 252-21, Pasadena, CA 91125 United States
AU: Klotz, J
EM: klotz@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Telegrafenberg D-14473, Potsdam, Germany
AB: We use InSAR, GPS, and seismic data to constrain the location of co-seismic and post-seismic slip on the subduction interface in southern Peru and northern Chile. We focus on the July 30, 1995, ${M}_{w}$~8.1 and the January 30, 1998, ${M}_{w}$~7.1 northern Chile earthquakes as well as the November 12, 1996, ${M}_{w}$~7.7 and June 23, 2001, ${M}_{w}$~8.4 southern Peru earthquakes. For all four earthquakes, we invert body-wave seismic waveforms and geodetic data (InSAR for all earthquakes and GPS where available) both jointly and separately for co-seismic slip. In northern Chile, we constrain the temporal and spatial evolution of post-seismic after-slip using about 30 interferograms spanning 1995-2000 and GPS data from the German SAGA array (spanning 1995-1997, including vertical displacements). In southern Peru, we use InSAR data, and GPS data from the Arequipa station to constrain post-seismic after-slip. Comparison of these events provides insight into the rupture process of large subduction zone earthquakes and the mechanisms of post-seismic after-slip. The plate tectonic setting for all the earthquakes is similar (convergence rate, plate age, etc.), but the amount of post-seismic after-slip is different. There is significant slip after the 2001 earthquake (equivalent to approximately 20% of the co-seismic moment), but compared to other recent subduction zone earthquakes, there is little slip following the other three events. The different amounts of post-seismic slip are not obviously related to differences in the dynamic ruptures of each event, but might be related to along-strike variations in material properties (like sediment thickness).
DE: 1208 Crustal movements--intraplate (8110)
DE: 1242 Seismic deformations (7205)
DE: 1243 Space geodetic surveys
DE: 7209 Earthquake dynamics and mechanics
SC: Seismology [S]
MN: 2003 Fall Meeting