RAMPING UP EASTERN U.S. SEISMIC HAZARDS STUDIES – PLANNING FOR INCREASED FUNDING PROPOSED IN THE 2013 PRESIDENT'S BUDGET

The magnitude 5.8 earthquake in central Virginia on August 23, 2011 was felt by millions of people in 20 states, shut down a nuclear power plant for several months, and resulted in over $150 million in property damages. This earthquake occurred in the previously recognized central Virginia seismic zone (CVSZ), which has a long history of persistent, small-to-moderate (M < 5.0) activity. This event provided dramatic evidence of the earthquake hazard in the eastern U. S. and the potential for widespread disruption and damage. The President’s 2013 targeted funding increase provides an exceptional opportunity to advance our understanding of the causes of earthquakes in the eastern U. S., to refine our assessments of seismic hazard mapping, and to promote the implementation of this new knowledge in building codes and other public safety measures.

It is generally thought that eastern earthquakes occur on ancient geologic faults that have been re-activated by the modern stress conditions in the Earth’s crust. It is also generally accepted that historically active areas, such as the CVSZ, have higher seismic hazard than areas that are historically less active or aseismic. The proposed scientific approach is to evaluate these tenets by examining in detail the geologic and tectonic setting and conditions of the Virginia earthquake and then use this information as a template to identify similar locations in the eastern U.S. Target regions of interest are eastern South Carolina, eastern Tennessee, northeastern New Jersey (New York City area), northern New York, and central New Hampshire – all areas of low level but persistent seismicity. Particular attention will be given to areas near large urban centers. Activities will include analysis of new airborne geophysical data acquired in the CVSZ in 2012, regional paleoseismic studies, including evidence of liquefaction, tsunamis, and quake damage to delicate formations in caves, a renewed effort to expand the record of historical accounts of past earthquakes, application of seismic imaging to identify buried faults, study of seismic wave attenuation, and analyses of site response due to soft soils in urban centers. Many of the studies proposed above will benefit from the dramatic increase in the number of seismic stations that the EarthScope project will bring into the area in 2013.