HR: 17:00h
AN: S34A-05    [Abstracts]
TI: Faults Interaction Through Off-fault Tensile Cracks Induced by 3D Dynamic Shear Rupture Propagation
AU: * Dalguer, L A
EM: ldalguer@moho.sdsu.edu
AF: Department Of Geological Science, SDSU, Campanile dr, San Diego, ca 92182 United States
AU: Day, S M
EM: day@moho.sdsu.edu
AF: Department Of Geological Science, SDSU, Campanile dr, San Diego, ca 92182 United States
AB: We developed 3D dynamic rupture models of multi-parallel strike slip faults using the Discrete Element Method (DEM) to study the interaction between step over faults considering off-fault open crack induced by the dynamic stress generated during shear rupture. The slip weakening friction model for shear rupture and the model of Dalguer et al. 2003 for the tensile cracks is used. We test two models: first, the multi-parallel shear faults reach the free-surface (depth H=0.0km) and second, they are embedded H=2.1 km below the free-surface. The off-fault open cracks produce inelastic deformation in the surrounding volume of the faults. This off-fault dissipation mechanism results in distortion of the fault slip profile and a reduction of the shear rupture velocity due to energy loss during open crack propagation. However, these open cracks that take place in the tensional side of the fault, also produce fault linkage and coalescence and promote fault nucleation and growth of shear rupture on the neighbor faults. This second fault may coalesces with a third fault as well and so on. The interaction between the faults creates naturally step over faults due to the heterogeneous shear stress change distribution in the neighbor faults radiated from the rupture of the first fault. The free-surface effects also take an important roll in the fault interaction. When the shear fault reaches the free-surface it enhances the tensile cracks propagation, then facilitate the shear fault interaction. The interaction between the faults occur when abrupt stopping of the shear rupture cause tensile crack propagation. In addition, the interaction of parallel faults results in a heterogeneity shear stress distribution on the neighbor faults, forming barriers and asperity patches naturally.
DE: 7209 Earthquake dynamics (1242)
DE: 7223 Earthquake interaction, forecasting, and prediction (1217, 1242)
DE: 8004 Dynamics and mechanics of faulting (8118)
DE: 8010 Fractures and faults
SC: Seismology [S]
MN: Fall Meeting 2005