COLLABORATIVE RESEARCH: Continuation of A GPS-Based Study of A slip along The Riveara Subduction Interface Following The October 9, 1995 M=8 Jalisco Earthquake

University Of Wisconsin-Madison, Madison WI

Investigators

Abstract

EAR-9909321 DeMets We propose to continue a GPS-based study of the Rivera and northern Cocos subduction zones using an existing 24 site GPS network in western Mexico. Our specific goals are to discriminate between the predictions of elastic-slip-at-depth and viscous-flow-at-depth models for postseismic motion, to determine whether postseismic slip decays within a few years of the earthquake and is immediately followed by a resumption of steady interseismic strain accumulation, to assess whether interseismic strain accumulation is focused along parts of the subduction interface that accommodated the most coseismic slip, to determine whether barriers to the coseismic rupture (e.g. velocity-strengthening regions) correspond to regions of significant afterslip, as might be expected if friction along the subduction fault obeys rate- and state-variable constitutive laws, and to determine whether interseismic strain is consistent with a fully-locked fault, as comparisons of expected plate slip versus coseismically-released slip suggest. Toward these goals, we will continue annual and continuous occupations of the network, and intensive modeling of postseismic displacements.