HR: 09:30h
AN: G21D-07    [Abstracts]
TI: Models of Postseismic Deformation Following the 2003 Tokachi-oki Earthquake and Interseismic Deformation in Northern Japan
AU: * Hetland, E A
EM: ehetland@alum.mit.edu
AF: Seismological Laboratory, Caltech, 1200 E California Blvd., Pasadena, CA 91125, United States
AU: Simons, M
EM: simons@caltech.edu
AF: Seismological Laboratory, Caltech, 1200 E California Blvd., Pasadena, CA 91125, United States
AU: Owen, S E
EM: Susan.E.Owen@jpl.nasa.gov
AF: Jet Propulsion Laboratory, 4800 Oak Grove Dr., Pasadena, CA 91109, United States
AU: Dunham, E M
EM: edunham@fas.harvard.edu
AF: Harvard University, 20 Oxford St., Cambridge, MA 02138, United States
AU: Webb, F
EM: fhw@jpl.nasa.gov
AF: Jet Propulsion Laboratory, 4800 Oak Grove Dr., Pasadena, CA 91109, United States
AB: Transient deformation is frequently observed following large earthquakes on subduction interfaces, and is commonly interpreted to result from aseismic slip on the megathrust fault-zone (MFZ). Kinematic models typically reveal that postseismic afterslip is spatially anti-correlated with coseismic slip, indicating that the majority of afterslip occurs in non-seismogenic portions of the MFZ. Since the spatio-temporal distribution of afterslip is dictated by the MFZ rheology, geodetic observations of postseismic deformation have the potential to place constraints on the MFZ rheology. In general, postseismic deformation can rarely be considered independent of all previous ruptures, as transient postseismic deformation affects the interseismic deformation late in a seismic cycle. Hence, simultaneously modeling postseismic deformation with the steady deformation observed in the years prior to a megathrust earthquake, may further constrain the rheology. We recently developed a 3D model consisting of a finite fault, embedded in a half-space, with imposed ruptures on regions of the fault, and stress- dependent postseismic and interseismic slip on areas that are not locked during the interseismic periods (either stable or conditionally stable regions of the MFZ). This model is based on the formulation of Rice (1993); however, we only solve for aseismic slip, and impose coseismic slip in prescribed regions. The rheology of the MFZ can be linear viscous, stress-dependent viscous, or rate- and state-dependent friction. Our model is applicable to any fault geometry, but in this presentation we only consider the 2003 M8 Tokachi-oki earthquake on the southern Kuril trench megathrust in northern Japan.
DE: 1207 Transient deformation (6924, 7230, 7240)
DE: 1242 Seismic cycle related deformations (6924, 7209, 7223, 7230)
DE: 7240 Subduction zones (1207, 1219, 1240)
SC: Geodesy [G]
MN: 2007 Fall Meeting