Deformation at the leading edge of thrust faults
Abstract
The 1999 Chi-Chi earthquake in Taiwan provides an excellent case for studying earthquake faulting. Escarpments 1--10 meters high were formed along an earthquake rupture extending for 100 km. The deformation zone was markedly asymmetric, much wider in the hanging wall than the footwall. Trenches excavated across the escarpment showed well-preserved fault and fold structures at scales ranging from millimeters to meters. To understand the development of deformation zones and escarpment shapes during thrusting, I undertook several different modeling and observational approaches. (1) A two-dimensional fault slip propagation model shows that deformation zones can develop as fault slip propagates to the surface. (2) A modified dislocation model reproduces various observed escarpment profiles and shows that they depend critically on fault geometry. (3) Mapping of faults in the Chushan trench and multi-fault dislocation modeling showed that multiple faults can produce monocline-like escarpments. Taken together, these studies provide new insights into deformation at the leading edge of thrust faults.
Degree
Ph.D.
Advisors
Johnson, Purdue University.
Subject Area
Geology|Geophysics|Geophysical engineering
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