The Southern Appalachian Cooperative Seismic Network (SACSN) provides modern instrumental coverage of southern Appalachian seismicity. SACSN stations operated by Virginia Tech under this award have been upgraded with three-component sensors and high-dynamic-range capability. Calibrated waveform data are available via the Internet. During the past year, 20 earthquakes in Virginia and West Virginia were detected and located by Virginia Tech. The entire catalog of instrumentally detected and located earthquakes for the southeastern U.S. have been posted by Virginia Tech to the online CNSS Composite Catalog. Published research during this year include studies of eastern Tennessee seismicity and a probabilistic seismic hazard assessment for the Charleston, SC, area.
The amplitude and duration of ground motion are important considerations for engineering analysis. However, the duration of shaking is not modeled routinely in probabilistic seismic hazard assessments. Because input energy for an elastic oscillator depends upon the duration as well as the amplitude of motion, energy-based prediction models may have application in the identification of scenario events for dynamic analysis. This study develops models which predict the elastic input energy as a function of magnitude and distance. Work in progress will assess the effect these models have on probabilistic seismic hazard estimates, in regard to the definition of events (magnitude and distance) contributing significantly to hazard for specified return periods.