HR: 0800h
AN: S21A-0262    [Abstracts]
TI: ShakeMap Implementation for the Upper Mississippi Embayment
AU: * Brackman, T B
EM: tbrackmn@memphis.edu
AF: University of Memphis CERI, 3876 Central Ave. Suite 1, Memphis, TN 38152-3050 United States
AU: Withers, M
EM: mwithers@memphis.edu
AF: University of Memphis CERI, 3876 Central Ave. Suite 1, Memphis, TN 38152-3050 United States
AU: Wald, D
EM: wald@usgs.gov
AF: U.S. Geological Survey, Denver Federal Center PO Box 25046, MS966, Lakewood, CO 80225 United States
AB: ShakeMap is a tool using basic seismological concepts for the rapid generation of maps of various types of ground motion and shaking intensity following significant earthquakes and is based on both observed and modeled data. ShakeMap assists with emergency operation plans and informs emergency responders, emergency management personnel and engineers of potential damage due to strong shaking. The media and public are informed of strong motion by simple map formats, with downloadable images and files also available. To date, ShakeMap has been used in several regions of the western U.S. We adapted the ShakeMap operational requirements to eastern North America (specifically, the Upper Mississippi Embayment) by customizing the aspects of amplification, attenuation, and instrumental-intensity correlation. Grids with site-specific soil velocity based amplification factors were constructed from data compiled by Bauer (2001), resulting in a four-degree grid centered on the New Madrid Seismic Zone. Soil types were delineated to give velocities (Vs30) for each point on the grid. Equations from Borcherdt's (1994) four-step process to determine amplification factors were used to determine the scaling of peak ground motions at short and mid periods. For attenuation, the multiple weighted relations used in the CEUS portion of the 2002 National Seismic Hazards Maps (Frankel, 2002) were chosen, and we plan to upgrade ShakeMap to allow multiple regressions as soon as possible. In the meantime, Atkinson and Boore's (1995) relation was implemented and scenarios were run to determine its appropriateness. Next, the western U.S. regression relationship between Modified Mercalli Intensity and horizontal peak ground motions was compared to observed intensities for recent central United States. Finally, with this regionalized implementation, scenarios were conducted for the 1811-1812 New Madrid earthquake sequence and the results were compared to the observed isoseismals.
DE: 7299 General or miscellaneous
SC: Seismology [S]
MN: 2004 AGU Fall Meeting