Edgefield Earthquake Geophysical Experiment
Edgefield Earthquake Grpund Penetrating (GPR) Experiment
On February 14, 2014 there was a magnitude 4.1 earthquake felt over a large area in the southeastern United States (Figure 1). After some investigation the epicenter was located in Edgefield, SC with a focal mechanism demonstrating mostly reverse motion. Two days later another earthquake occurred in close proximity with mostly strike slip motion, which could possibly be related to the initial Valentine’s Day earthquake.
The southeastern United States, specifically South Carolina, has a history of damaging earthquakes, such as the 1886
Charleston Earthquake with a magnitude of 7.6 on the Richter scale (Murphy, 2006). Intraplate seismicity is poorly understood and the first step in mitigating hazards associated with earthquakes in the southeastern United States is to identify the faults in this region.
The purpose of this research sponsored by ESRI-SC is to identify the fault that caused the Edgefield earthquake on February 14th 2014. This fault has not yet been discovered and was the cause of a 4.1 magnitude earthquake. People from around the area, including myself, felt the earthquake shake for a brief moment and were left confused until they realized what phenomenon had just occurred. The initial earthquake occurred at 10:23 PM. It was a result of thrust faulting at about 5.2 km (3.2 mil) depth. The after shock was recorded as a magnitude 3.0 earthquake from strike slip faulting at
3:23 PM February, 16th 2014 at about 7.0 km (4.3 mi) depth. The data form this survey will be used to analyze this area for indicators of a fault. The survey consists of one 270 m resistivity survey, one 470 m GRP survey at 50 Mhz and one 475 m refraction survey, taken in two parts. The GRP was processed in Promax and the resistivity survey was processed in Earth Imager. The refraction survey was analyzed in Promax. The first breaks were identified to determine the velocities of the first and second layers. The images obtained from this survey will be used to detect any sign of a subsurface discontinuity. The goal is to determine a lateral and depth location of the Edgefield fault.