PRELIMINARY RESULTS OF FAULT COMPILATION MAPPING IN THE SEISMICALLY ACTIVE AREAS OF VIRGINIA

When a Mw 5.8 earthquake shocked central Virginia in August of 2011, it drew new attention to the need for seismic hazard preparedness along the east coast of the United States. In response to the earthquake, the Virginia Department of Mines, Minerals and Energy (VA DMME) – Division of Geology and Mineral Resources (DGMR) is completing a 3-year Hazard Mitigation Grant project funded by the Federal Emergency Management Agency (FEMA) and managed by the Virginia Department of Emergency Management (VDEM).

This project involves four major components: 1) to evaluate Virginia’s seismic history, 2) to compile an ArcGIS geodatabase of all known mapped faults and structural zones (e.g. mylonite zones, fault breccias) within the three seismically active areas of Virginia, 3) to analyze newly acquired high-resolution LiDAR elevation data in the 2011 epicentral area in an effort to identify previously unrecognized faults and/or topographic offset, and 4) to identify infrastructure and critical facilities that may be at risk during a future seismic event. When completed, this information and GIS data will be provided to the 12 planning districts, local emergency managers, and government officials within the seismically active areas of Virginia, along with interpretive materials and mitigation recommendations.

Currently, over 200 historic geologic maps, at scales ranging from 1:12,000 to 1:250,000, have been scanned and digitized into an ArcGIS relational geodatabase. Compiled from published and unpublished sources, field guides and reports, and theses and dissertations, these maps represent over 100 years of geologic knowledge and interpretation. Digital compilation of this myriad fault and structural data is currently underway, utilizing selective field checking to resolve discontinuities in the fault mapping. Collaboration with scientists from the U.S. Geological Survey, Virginia Tech, and the College of William and Mary will help to improve the accuracy of the compilation.