HR: 0800h
AN: S51A-0218    [Abstracts]
TI: ShakeMap at the Pacific Northwest Seismic Network
AU: * Hartog, R
EM: renate@ess.washington.edu
AF: Department of Earth and Space Sciences, University of Washington, Box 351310, Seattle, WA 98195, United States
AU: Bodin, P
EM: pbodin@ess.washington.edu
AF: Department of Earth and Space Sciences, University of Washington, Box 351310, Seattle, WA 98195, United States
AU: Gomberg, J
EM: gomberg@usgs.gov
AF: US Geological Survey, University of Washington, Box 351310, Seattle, WA 98195, United States
AU: Gustafson, B
EM: billg@ess.washington.edu
AF: Department of Earth and Space Sciences, University of Washington, Box 351310, Seattle, WA 98195, United States
AU: Malone, S
EM: steve@ess.washington.edu
AF: Department of Earth and Space Sciences, University of Washington, Box 351310, Seattle, WA 98195, United States
AU: Palmer, S
EM: spalmer@geodesigninc.com
AF: GeoDesign, Inc., 15575 SW Sequoia Parkway -Suite 100, Portland, OR 97224, United States
AU: Pratt, T
EM: tpratt@ocean.washington.edu
AF: US Geological Survey, University of Washington, Box 351310, Seattle, WA 98195, United States
AU: Steele, B
EM: bill@ess.washington.edu
AF: Department of Earth and Space Sciences, University of Washington, Box 351310, Seattle, WA 98195, United States
AU: Vidale, J
EM: vidale@ess.washington.edu
AF: Department of Earth and Space Sciences, University of Washington, Box 351310, Seattle, WA 98195, United States
AU: Wald, D
EM: wald@usgs.gov
AF: US Geological Survey, MS 966, Denver Federal Center, Box 25046, Denver, CO 94025, United States
AU: Weaver, C
EM: craig@ess.washington.edu
AF: US Geological Survey, University of Washington, Box 351310, Seattle, WA 98195, United States
AU: Wong, I
EM: Ivan_Wong@URSCorp.com
AF: URS Corp., 1333 Broadway, Suite 800, Oakland, CA 94612, United States
AB: We summarize efforts to tailor ShakeMap to the Pacific Northwest Seismic Network (PNSN), and to increase the resolution in the major urban areas. Our initial implementation of ShakeMap employed parameters based on data from mostly larger earthquakes outside the Pacific Northwest. The PNSN automatically generates a 45- arcsec ShakeMap for any earthquake of M_d ≥ 3.0 in the Puget Sound region and for M_d ≥ 4.0 earthquakes in Washington and Oregon. ShakeMap uses 3-component, real-time data from 91 strong motion, 34 broadband, and 70 Earthscope Transportable Array stations. We also automatically incorporate data from dial- up stations of the National Strong Motion Program. High-resolution (7.2 arcsec) ShakeMaps for the Seattle area have just come on-line thanks to the availability of a new, more detailed geologic map. We use data from the PNSN and other sources to derive new region-specific ground motion attenuation relations and site corrections. Preliminary results suggest that default attenuation relations included with the ShakeMap package over-predict Pacific Northwest ground motions, especially at larger distances and for deep (≥ 20km) earthquakes. We will make similar comparisons with the Next Generation Attenuation relations, to be used in future ShakeMap releases, and modify the relations if warranted. To improve site corrections we compared site amplification measurements and local magnitude residuals (available for most of the PNSN stations) to measured values of V_s30 at co-located and nearby sites. These correlate well and thus provide useful proxies for V_s30 for use in ShakeMap. We also found correlations between V_s30 estimates and the age and rock type of mapped geologic units, providing a geologically constrained means of interpolating between sites with more direct V_s30 estimates. Finally, our ShakeMaps will improve because we continue to add stations to the PNSN, providing additional direct measures of ground motion.
DE: 7212 Earthquake ground motions and engineering seismology
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 7294 Seismic instruments and networks (0935, 3025)
SC: Seismology [S]
MN: 2007 Fall Meeting