Light earthquake felt throughout South Carolina

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Just as the state saw the winter storm move on last week, an earthquake was reported. The magnitude 4.1 seismic event occurred Friday with the epicenter 7 miles W/NW of Edgefield.

Dr. Steven C. Jaumé of the South Carolina Earthquake Education and Preparedness, Department of Geology and Environmental Geosciences at the College of Charleston reported:

A magnitude 4.1 earthquake occurred near Edgefield, South Carolina at 10:23 PM on February 14. The earthquake was felt throughout South Carolina, including here in the greater Charleston area, and into Georgia, North Carolina and Tennessee. This is the largest earthquake in South Carolina since a magnitude 4.4 earthquake offshore of Edisto Island in 2002.

While earthquakes in South Carolina are most common in the Middleton Place-Summerville Seismic Zone near Charleston, they do occur throughout the state. The largest recorded earthquake in the upstate of South Carolina was the 1913 Union County earthquake, which had an estimated magnitude of 5.5.

The Valentine’s Day earthquake occurred in the part of South Carolina that has a geologic history similar to that of Louisa County, Virginia, the location of the magnitude 5.8 earthquake in 2011 that damaged buildings in Washington, DC, including the Washington Monument. The faulting mechanism of Friday night’s earthquake is also similar to the 2011 Virginia earthquake. This is a reminder that large damaging earthquake can occur in all parts of South Carolina, not just in the Charleston area.

The seismograms from the earthquake clearly show the effect of the sediments of South Carolina’s coastal plain on the strength of ground motion. Seismometer 158A in Hollywood, South Carolina (west of Charleston) clearly shows stronger motion in the horizontal directions (North-South and East-West) than W54A in Campobello, South Carolina (in the upstate). This occurs even though W54A is closer to the earthquake than 158A.

This shows that the same magnitude earthquake in the Low Country of South Carolina would be expected to cause greater damage than a similar size earthquake in the hard rock of the upstate.

The date being analyzed comes from the seismometers of the EarthScope (http://www.earthscope.org/) program’s USArray (http://www.usarray.org/), a National Science Foundation supported program that maintains a pool of 400 seismometers that have been moving across the USA, starting in California in 2003. The USArray seismometers arrived in South Carolina in early 2013. Some will stay permanently in South Carolina and others will be moved to Alaska starting in late 2014.

Though no major damage was reported, however SCDOT did send out Bridge Inspection teams to visually check bridges for any lateral or longitudinal shift. According to SCDOT, 12 Bridge Inspectors and other Engineering personnel were involved in assessments. The following information was reported:

Engineering Districts 1, 4, 5 & 6: No response required.

Engineering District 2 (Abbeville, Anderson, Edgefield, Greenwood, Laurens, McCormick, Newberry, and Saluda Counties): Bridge inspectors will check locally near the epicenter and US 378 @ Savannah River and US 29 @ Savannah River below Lake Hartwell Dam and SC 34 @ Saluda River below Lake Greenwood. Particular focus will be placed on the area around Edgefield. SCDOT McCormick Maintenance Engineering performed a nighttime check near the Edgefield/McCormick county line and reported no unusual sightings.

Engineering District 3 (Greenville, Oconee, Pickens, and Spartanburg Counties): Bridge inspectors will check US 123 @ Lake Hartwell and US 76 @ Chattooga River and around the Oconee Nuclear/Keowee hydroelectric area.Engineering District 7: (Aiken, Allendale, Bamberg, Barnwell, Calhoun, Clarendon, Hampton, and Orangeburg Counties): Bridge inspectors will check around the Savannah River area and I-20 inland. The I-20 Savannah River bridges are owned and maintained by Georgia DOT (GDOT); coordination efforts are underway with GDOT to ensure awareness of the event and of SCDOT’s response plans.

Dr. Steven C. Jaumé of the South Carolina Earthquake Education and Preparedness, Department of Geology and Environmental Geosciences at the College of Charleston reported:

A magnitude 4.1 earthquake occurred near Edgefield, South Carolina at 10:23 PM on February 14, 2014. This earthquake was felt throughout South Carolina, including here in the greater Charleston area, and into Georgia, North Carolina and Tennessee. This is the largest earthquake in South Carolina since a magnitude 4.4 earthquake offshore of Edisto Island in 2002.

While earthquakes in South Carolina are most common in the Middleton Place-Summerville Seismic Zone near Charleston, they do occur throughout the state. The largest recorded earthquake in the upstate of South Carolina was the 1913 Union County earthquake, which had an estimated magnitude of 5.5.

The Valentine’s Day earthquake occurred in the part of South Carolina that has a geologic history similar to that of Louisa County, Virginia, the location of the magnitude 5.8 earthquake in 2011 that damaged buildings in Washington, DC, including the Washington Monument. The faulting mechanism of Friday night’s earthquake is also similar to the 2011 Virginia earthquake. This is a reminder that large damaging earthquake can occur in all parts of South Carolina, not just in the Charleston area.

The seismograms from the earthquake clearly show the effect of the sediments of South Carolina’s coastal plain on the strength of ground motion. Seismometer 158A in Hollywood, South Carolina (west of Charleston) clearly shows stronger motion in the horizontal directions (North-South and East-West) than W54A in Campobello, South Carolina (in the upstate). This occurs even though W54A is closer to the earthquake than 158A.

This shows that the same magnitude earthquake in the Low Country of South Carolina would be expected to cause greater damage than a similar size earthquake in the hard rock of the upstate.

The date being analyzed comes from the seismometers of the EarthScope (http://www.earthscope.org/) program’s USArray (http://www.usarray.org/), a National Science Foundation supported program that maintains a pool of 400 seismometers that have been moving across the USA, starting in California in 2003. The USArray seismometers arrived in South Carolina in early 2013. Some will stay permanently in South Carolina and others will be moved to Alaska starting in late 2014.