HR: 1340h
AN: G13B-1236    [Abstracts]
TI: GPS Seismology Results from the 2002 M=7.9 Denali Fault Earthquake
AU: * Cassidy, J F
EM: jcassidy@nrcan.gc.ca
AF: Geological Survey of Canada, 9860 West Saanich Road, Sidney, BC V8L 4B2, Canada
AU: Bilich, A
EM: Andria.Bilich@noaa.gov
AF: National Geodetic Survey, 325 Broadway St. E/GC2, Boulder, CO 80305, United States
AU: Larson, K M
EM: kristinem.larson@gmail.com
AF: Dept. Aerospace Engineering Sciences, University of Colorado, University of Colorado UCB 429, Boulder, CO 80309, United States
AB: In order to properly combine traditional seismic measurements with high-rate (1-Hz) GPS positions, we must first understand the relative strengths of each data type and the inherent precision and accuracy of high-rate GPS positions. Here, we characterize the strengths and limitations of GPS seismology with a case study of the Mw=7.9 Denali Fault earthquake of 2002, utilizing high-rate GPS data from 23 stations across much of western North America to epicentral distances of about 3500 km. First, after applying error reduction methods to GPS displacements, we estimate noise floors of 4-10 mm in the horizontal, and 10-20 mm in the vertical for these stations and this event. Next, we access the accuracy of these GPS positions by comparing four collocated GPS and broadband seismometer recordings in western Canada. By integrating the seismic data to displacement and applying common filters to the seismic and GPS data, we find that the high-rate GPS and broadband seismic data are in excellent agreement for the 10-50 second period surface waves of the Denali earthquake as long as the amplitudes exceed about 1 cm. Finally, given this validation of the GPS displacements for this event, the complete "GPS seismogram" dataset for the 23 stations is now archived at IRIS and available for public use in future studies of the 2002 Denali fault earthquake. Integrating seismic and GPS data provides much larger data sets for studies of the earthquake source (including mechanism and directivity) and wave propagation effects.
DE: 1294 Instruments and techniques
DE: 1295 Integrations of techniques
DE: 7209 Earthquake dynamics (1242)
DE: 7255 Surface waves and free oscillations
DE: 7294 Seismic instruments and networks (0935, 3025)
SC: Geodesy [G]
MN: 2007 Fall Meeting