[J06-1] The spectrum of fault-zone deformation processes (from slow slip to earthquake) I

[J06-1-05] EFFECTS OF THE GEOMETRY OF THE MEXICAN SUBDUCTION ZONE TECTONIC-INTERFACE ON THE STRESS TRANSFER DUE TO INTERPLATE SLIP EVENTS.

^○Miguel Angel Santoyo¹, Vladimir Kostoglodov², Carlos Mendoza³ (1.Institute of Geophysics U. Michoacan, National Autonomous University of Mexico, Morelia, Mexico, 2.Institute of Geophysics, National Autonomous University of Mexico, Mexico City, Mexico., 3.Center of Geosciences, National Autonomous University of Mexico, Queretaro, Mexico.)

We analyze in this work the effects of the tectonic interface geometry of the Mexican subduction zone on the coulomb stress transfer produced by large interplate earthquakes and slow slip events, using a 3D subducting slab model and explicit slip distributions. The interface geometry used here was previously obtained based on seismicity depth profiles along the subduction zone. As a reference for the assessments, we first obtained the stress change over extended fault planes; for slow slip events we considered three plane segments with different dip angles and for earthquakes (M<8.0) we used a single extended fault plane. Next we computed the stress transfer for the same slip distributions along the 3D interface. In all cases the interface surface was discretized by 2.0Km x 2.0Km segments, setting the observing points along the same surface in a staggered-type grid, avoiding in this way possible singularities. Stress tensor changes were computed for a 3D half-space, and analyzed using the Coulomb Failure Stress criterion. The stress changes due to each subfault from each earthquake were computed on each grid segment of the interface and resolved along its specific normal and slip directions. This computation procedure implied that for a given earthquake, or slow slip event with a specific slip distribution, the coulomb stress change distribution could vary depending on its relative location along the surface. Results are presented and compared for the plane segments and the 3D tectonic interface. The stress changes inside the main rupture patches showed relative small variations between both assumptions; however, relatively larger variations could be found outside the main patches, especially where the interface presented bendings along the strike or dip directions. Results suggest that the assumption of planar tectonic surfaces should be carefully explored for this kind of analyses in this region.