EarthScope RAPID: Geodetic and seismological response to the Mineral, VA Earthquake, 23 August, 2011
collaborative with Frank Pazzaglia and Claudio Berti Lehigh University, Seth Stein Northwestern University.
The M 5.8 Louisa County, VA earthquake of 23 August, 2011, is a sobering reminder of how little we know about the lithosphere and active tectonics of plate interiors, including passive continental margins. Seismicity and deformation within plate interiors are neither predicted nor well described by plate tectonics. While moderate in size compatred to plate boundary earthquakes, ground shaking associated with the Mineral Earthquake in Louisa County VA was felt over a larger region of the U.S. than any previous instrumentally recorded earthquake due to efficient energy propagation through crystalline bedrock that underlies much of the eastern margin of the U.S. Damage to homes, schools, historic buildings, and critical infrastructure was moderately heavy in the epicentral region. Had this earthquake occurred closer to a large city the potential for damage would have been much greater.
GPS station, Louisa County, VA.
The Mineral VA earthquake occured on the northern end of the Central Virginaia Seismic Zone, a persistent cluster of seismicity similar to the Reading Landcaster Seismic Zone in Pennsylvania. In the wake of the Mineral Earthquake and in collaboration with the USGS and IRIS we operated and maintained a series of seismometers to record aftershocks for up to a year. Over 340 aftershocks define a clear NE-SW striking SE dipping fault plane extending 7-9 km along stirke at depths of 1-7 km. In collaboration with UNAVCO, we also installed 2 permanent GPS stations, one on either side of the rupture plane. Fieldwork has identified geomorphic markers associated with longer term deformation close to site of the fault.
publications and abstracts
Wolin, E., S. Stein, F. Pazzaglia, A. Meltzer, A. Kafka, and C. Berti (2012), Mineral, Virginia, earthquake illustrates seismicity of a passive-aggressive margin, Geophys. Res. Lett., 39, L02305, doi:10.1029/2011GL050310.
Mineral, VA Earthquake Demonstrates the Passive Aggressive Margin of Eastern North America, EarthScope Newsletter Spring 2012
Berti, Claudio, Pazzaglia, Frank J., Meltzer, Anne S., and Harrison, Geomorphic Evidence for Persistent Faulting Consistent with the 23 August, 2011, Louisa County VA, Earthquake, 2012, Paper No. 154-15, presented at 2012 GSA Anual Meeting, Charlotte NC., 4-7 Nov.
Frank J. Pazzaglia, Anne Meltzer, Claudio Berti, Josh C. Stachnik, Seth A. Stein, William E. Holt, 2012, Evidence for persistent faulting consistent with the 23 August, 2011 Louisa County, VA earthquake, Abstract S53I-08, presented at 2012 Fall Meeting, AGU, San Francisco, Calif., 5-9 Dec.