Crustal Deformation Measurements in the Vicinity of Vandenberg Air Force Base

摘要

Recent geological and geodetic studies have suggested that the region surroundingVandenberg Air Force Base, CA, is undergoing active crustal deformation, with important implications for both the geodetic stability and the seismogenic potential of the Western Test Range. In 1989, funding was received (AFOSR 89-0400) for the purchase of several GPS receivers. Beginning in 1990, a series of measurements was funded (AFOSR 90-0339) to determine the magnitude and spatial distribution of deformation in the Santa Maria Fold and Thrust Belt and subsequently to install continuously operating GPS stations at Vandenberg and the China Lake Naval Center. GPS measurements in the thrust belt and surrounding area reveal a zone of both strike slip and compressive deformation not readily identifiable with known faults. Experience with the Landers and Northridge earthquakes underscores findings here that 'blind' thrust faults likely serve as the principal architects of the topography in the thrust belt and the basin areas. Annual or biennial GPS measurements into the future will allow refinement of the estimates of deformation and the geodynamic motions in southern California. (MM).