DeMets 9526419 The PI's propose a GPS project that is designed to measure crustal deformation across a network of geodetic monuments spanning that state of Jalisco in western Mexico. The Jalisco region is a volcanically and tectonically complex geologic province that overlies the subducting Rivera and Cocos plates and exhibits evidence for modern deformation primarily confined to three continental rifts. Their goal is to understand the relative kinematics and hence the coupling of the oceanic and continental plates in this regions, as well as to test several hypotheses concerning the link between the motions of the subducting plates, seafloor features entering the subduction zone, and the observed onshore deformation. These hypotheses have previously been untestable due to a lack of reliable observations of the regional strain field. With modern GPS technology, the required measurements are now feasible. Observations of Jalisco block velocities with respect to nearby sites on the North American plate could also permit us to test the intriguing, but speculative hypothesis that rotation of a semi-rigid Jalisco is responsible for the observed deformation along its bordering faults. The October 1996 unexpected magnitude 7.6 earthquake in this area provides a unique opportunity to study the coseismic and postseismic strains in the Jalisco as well.
