HR: 17:45h
AN: G14A-08    [Abstracts]
TI: Using Finite Element Meshes Derived from the SCEC Community Fault Model to Evaluate the Effects of Detailed Fault Geometry and Material Inhomogeneities
AU: * Williams, C A
EM: willic3@rpi.edu
AF: Rensselaer Polytechnic Institute, Dept. of Earth & Environmental Sciences, Science Center 1W19, Troy, NY 12180, United States
AU: Gable, C W
EM: gable@lanl.gov
AF: Los Alamos National Laboratory, Earth and Environmental Science, Los Alamos, NM 87545, United States
AU: Hager, B H
EM: bhhager@mit.edu
AF: Massachusetts Institute of Technology, Dept. of Earth, Atmospheric and Planetary Sciences, Cambridge, MA 02139, United States
AU: Lu, J
EM: johnnylu@MIT.EDU
AF: Massachusetts Institute of Technology, Dept. of Earth, Atmospheric and Planetary Sciences, Cambridge, MA 02139, United States
AB: To make realistic assessments of fault slip inferred from surface geodetic observations, we need to know the sensitivity of our predicted surface deformation field to additional factors that may not be accurately represented in the model. Two primary factors that may influence our predicted results are the detailed geometry of the faults in the model and the variations in material properties in the region under investigation. As a step in addressing the potential importance of these factors, we compare finite element computations of varying model complexity against those obtained using the analytical model of Meade and Hager (JGR, 2005). We use meshes derived from the Community Fault Model (CFM) to represent the detailed geometry for a small portion of the San Andreas fault system. This is a departure from previous work, where we used a derived Community Block Model (CBM) to provide airtight volumes for meshing. This new approach allows us to more easily include more faults and greater geometrical detail depending on the problem under consideration, and is more in keeping with the fractal nature of fault networks. Using this method, we have produced meshes including as many as 90 of the faults from the CFM, with the capability to include all CFM faults. We perform three different comparisons using four different models. We first compare analytical results using CFM-R (a coarser rectangularized version of the CFM) against a finite element representation of CFM-R assuming homogeneous elastic properties. This allows us to evaluate the accuracy of the finite element solution to insure the validity of our results. We then compare finite element solutions using CFM and CFM-R to evaluate the effects of including detailed fault geometry, again assuming homogeneous material properties. Finally, we compare finite element solutions with homogeneous and vertically-layered elastic property variations, both using the same CFM-derived mesh, thus providing a first-order estimate of the influence of material property variations on the predicted surface deformation field.
DE: 0545 Modeling (4255)
DE: 1209 Tectonic deformation (6924)
DE: 8020 Mechanics, theory, and modeling
DE: 8111 Continental tectonics: strike-slip and transform
DE: 8158 Plate motions: present and recent (3040)
SC: Geodesy [G]
MN: 2007 Fall Meeting