HR: 17:00h
AN: T54C-05    [Abstracts]
TI: Spatio-temporal complexity of continental intraplate seismicity: insights from geodynamic modeling and implications for seismic hazard estimation
AU: Liu, M
EM: lium@missouri.edu
AF: University of Missouri-Columbia, 101 Geology Building, MU, Columbia, MO 65211, United States
AU: * Li, Q
EM: li@lpi.usra.edu
AF: Lunar and Planetary Institute, USRA, 3600 Bay Area Blvd., Houston, TX 77058, United States
AU: Stein, S
EM: seth@earth.northwestern.edu
AF: Northwestern University, 1850 Campus Drive, Evanston, IL 60208, United States
AB: Continental intraplate seismicity, which cannot be readily explained by plate tectonic theory, has remained puzzling. Observations from different continents show complex spatiotemporal patterns of intraplate seismicity: both spatial clustering in seismic zones and scattering across entire continents; temporal clustering followed by long period of quiescence; and migration of seismicity from one seismic zone (or region) to another. Thus assessment of earthquake hazard based on the limited historic record may be biased toward overestimating the risks in regions of recent large earthquakes and underestimating the risks where seismicity has been quiescent. We have simulated the spatiotemporal evolution of intraplate seismicity in a 3D viscoelastic finite element model. The model incorporates tectonic loading, crustal failure, and coseismic and postseismic stress evolution. With pre-specified perturbations of crustal strength, the model predicts various spatiotemporal patterns of intraplate seismicity: spatial clustering (in narrow belts) and scattering ( across large regions) in hundreds of years, networked seismic belts in thousands of years, and apparently randomly scattered events over tens of thousands of years. The model results also show temporal clustering of intraplate earthquakes in seismic zones. The predicted spatial-temporal clustering results mainly from coseismic and postseismic stress migration. By considering continuous strength weakening following a large earthquake, the model predicts temporal earthquake clustering on an individual fault even in the absence of far-field loading. These results provide useful insights into the complex spatial-temporal pattern of intraplate seismicity, and call for caution when assessing intraplate earthquake hazard based on the short spatio-temporal record of instrumentally recorded seismicity.
DE: 7223 Earthquake interaction, forecasting, and prediction (1217, 1242)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 8103 Continental cratons
DE: 8123 Dynamics: seismotectonics
DE: 8164 Stresses: crust and lithosphere
SC: Tectonophysics [T]
MN: 2007 Fall Meeting