HR: 1330h
AN: S42B-0170    [PDF]
TI: Rapid Assessment of Shaking Impact Following Global Earthquakes
AU: * Earle, P S
EM: pearle@usgs.gov
AF: U.S. Geological Survey, MS 966 Box 25046, DFC, Denver, CO 80225 United States
AU: Wald, D J
EM: wald@usgs.gov
AF: U.S. Geological Survey, MS 966 Box 25046, DFC, Denver, CO 80225 United States
AU: Lastowka, L A
EM: llastowka@usgs.gov
AF: U.S. Geological Survey, MS 966 Box 25046, DFC, Denver, CO 80225 United States
AU: Donnelly, M J
EM: mdonnelly@usgs.gov
AF: U.S. Geological Survey, MS 966 Box 25046, DFC, Denver, CO 80225 United States
AB: The US Geological Survey's National Earthquake Information Center (USGS/NEIC) is developing a system to rapidly assess the overall impact of earthquakes around the globe. NEIC's near realtime global-earthquake solutions will be monitored to automatically identify quakes that likely caused human suffering or damage to infrastructure or will attract significant media attention. Our goal is to help the NEIC fulfill its mission to provide critical earthquake-related information to emergency response agencies, government agencies, the scientific community, the media, and the general public. The system will fill the gap between the time the hypocenter and magnitude are determined (minutes to an hour) and the time that onsite information is available through the media and other organizations (typically several hours to days). When complete, the system will provide an assessment of the situation based on estimated and any observed ground motions, total population exposed to varying degrees of shaking, and fragility of the impacted region. We expect that an automatic summary impact statement and associated alarms can be made within seconds of computing the ground-motion estimates, well before onsite damage estimates arrive. Development of the system is proceeding in stages, with each stage adding an increased level of detail and robustness to the impact statements. The initial system will be basic and empirical. It will issue alarms when an earthquake occurs where historical earthquakes of similar magnitude and depth have seriously impacted human life or infrastructure. This basic system will miss some significant events, but it will be relatively easy to implement and it will provide a baseline for further enhancements. Subsequent enhancements will include estimates of ground motion, population exposure, and regional fragility. Ground motion estimates will initially use regionally specific, empirical ground-motion attenuation relations. As details about the source are recovered, the estimated motions will evolve from point-source-based empirical to finite-fault-based empirical and to finite-fault-forward modeled synthetic amplitudes, augmented with empirical predictions. To this end, we are working collaboratively with C. Ji and D. Helmberger (Caltech) to expedite and automate the finite-fault inversion process (see abstract this meeting). Any ground motion observations (strong motions stations or Community Internet Intensities) will be used as constraints. Site amplification will be simple at first. We will use soil classification where known; otherwise, generic site terms will be used. The use of topography as a proxy for site conditions will also be investigated. Worldwide population databases in gridded form (e.g., LandScan developed by Oak Ridge National Laboratory) will be used to determine the total population exposed to various levels of shaking. For events not having significant populations at risk (e.g., off-shore or very deep earthquakes), it will be easy to determine when no response is warranted. However, when a large population is exposed to potentially damaging levels of shaking, the fragility of the region will be evaluated to constrain the likely overall impact. Fragility can be addressed in a several ways, but we will initially derive regionalized estimates based on the NEIC database of historical damaging earthquakes. We will later use socioeconomic considerations, as well as a qualitative assessment of construction and engineering practice.
DE: 7212 Earthquake ground motions and engineering
DE: 7223 Seismic hazard assessment and prediction
DE: 7230 Seismicity and seismotectonics
DE: 7299 General or miscellaneous
SC: Seismology [S]
MN: 2003 Fall Meeting