HR: 1340h
AN: S43B-1080    [Abstracts]
TI: A 3D Finite Element Analysis of the Intracontinental Deformation of Colombia and Venezuela and its Application to Regional Seismic Hazard Analysis
AU: * Mahdyiar, M
EM: mmahdyiar@air-worldwide.com
AF: AIR Worldwide Corporation, 131 Dartmouth Street, Boston, MA 02116 United States
AU: Shen-Tu, B
EM: bingming@air-worldwide.com
AF: AIR Worldwide Corporation, 131 Dartmouth Street, Boston, MA 02116 United States
AU: Rong, Y
EM: yrong@air-worldwide.com
AF: AIR Worldwide Corporation, 131 Dartmouth Street, Boston, MA 02116 United States
AB: The seismicity of Colombia and Venezuela are controlled by the convergences of the Caribbean and Nazca plates with the South America (SA) plate. The Caribbean plate is converging with SA plate from north in the east-southeast direction at 10-20 mm/yr. The Nazca plate is converging with SA plate from west in the northwest direction at about 60 mm/yr. This creates a complex intracontinental deformation within the region that is observed through regional earthquake activity. Although, there is a good correlation between the regional crustal seismicity and faults there are limited data on the slip rates of the crustal faults. Obtaining such information is critical for realistic seismic hazard analysis. It is the objective of this study to conduct a 3D finite element numerical study of the intracontinental deformation of northern Andes using GPS data as input to estimate slip rates of dominant regional crustal faults. GPS data provide a new and important dimension to how we estimate regional earthquake hazard, in which kinematic models have played key roles. Kinematic models are practical tools for interpreting regional GPS data into crustal deformation and strain fields, however they suffer from certain limitations. Regional variation of the material properties and various fault related complexities such as creeping are not considered in most kinematic models. Dynamic models, on the other hand, can address such issues if the models can be realistically constrained with reliable data, such as GPS velocities. However, because of the uncertainties in such data, regional GPS velocities need to be processed so that high frequency spatial variations that mostly represent the uncertainty in data rather than the local state of strain are filtered out. Processing the GPS data through a regional kinematic model can serve the purpose. Velocity fields derived from kinematic models are fairly smooth, self-consistent, and optimally represent the input GPS data in accordance with their levels of uncertainties. As such, a regional kinematic model can provide a smooth and self-consistent velocity field at the GPS stations for regional dynamic analysis. The results will be velocity and strain rate fields that are consistent with the regional kinematic model and, depending upon the complexity of the dynamic model, reflect the local material heterogeneities and faults related complexities. We have developed a 3D finite element dynamic model for northern Andes to calculate crustal deformation rates based on plate boundary convergence rates and a velocity field derived from a regional GPS-based kinematic model. Major regional faults are modeled as 3D weak shear zones. Different scenarios for plate convergence rates and faults shear properties are considered. About 90 GPS station velocities in the South America - Caribbean - Nazca plate boundary zone from various published literatures are used in this study. The GPS velocities from difference sources were first rotated to a common South American plate fixed reference frame. The results of the analysis provide information from which the faults slip rates are inferred. We will discuss the results and their implication in regional seismic hazard analysis.
DE: 1207 Transient deformation (6924, 7230, 7240)
DE: 1217 Time variable gravity (7223, 7230)
DE: 1240 Satellite geodesy: results (6929, 7215, 7230, 7240)
DE: 1242 Seismic cycle related deformations (6924, 7209, 7223, 7230)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
SC: Seismology [S]
MN: Fall Meeting 2005