By Nathan Ham
An earthquake on Sunday morning shook a lot of houses across the High Country and was felt as far away as Kentucky and South Carolina, according to the U.S. Geological Survey. Reports of people feeling the earthquake came from North Carolina, South Carolina, Tennessee, Virginia, West Virginia, and Kentucky.
The 5.2 magnitude earthquake was centered about 2.5 miles southeast of Sparta in Alleghany County. Numerous reports damage came from Sparta, including several broken items inside a Food Lion, in several homes, and large cracks in the pavement on streets throughout the town. Alleghany County issued a State of Emergency yesterday after the town had to be closed down for multiple reported gas leaks. The USGS Survey reported the depth of the earthquake was at 3.7 kilometers (approximately 2.3 miles).
According to the USGS, the earthquake occurred in the interior of the North American plate. Such mid-plate earthquakes are known as intraplate earthquakes and are generally less common than interplate earthquakes that happen near tectonic plate boundaries. This earthquake was preceded by at least four small foreshocks ranging from M 2.1-2.6, beginning about 25 hours prior to the mainshock.
“Large earthquakes are relatively uncommon in the region directly surrounding the August 9th M5.1 earthquake. Moderately damaging earthquakes strike the inland Carolinas every few decades, and smaller earthquakes are felt about once each year or two. In the 20th century, one earthquake M5 and larger occurred within 100 km to this August 9th events, a M5.2 in the Great Smoky Mountains in 1916. The largest recent earthquake to impact the east coast was the M5.8 Mineral Virginia earthquake on August 23rd, 2011, roughly 300 km to the northeast of this August 9th earthquake. The Mineral Virginia earthquake was felt widely across the east coast and caused slight damage,” the USGS said in a summary of the quake.
The USGS also noted that five aftershocks have taken place after the initial 5.1 magnitude earthquake on Sunday morning.
- 8 magnitude at 11:45 a.m. Sunday.
- 7 magnitude at 11:58 a.m. Sunday.
- 2.0 magnitude at 2:05 a.m. Monday.
- 2.2 magnitude at 4:43 a.m. Monday.
- 2.2 magnitude at 7:10 a.m. Monday.
“When there are more earthquakes, the chance of a large earthquake is greater which means that the chance of damage is greater,” the U.S. Geological Survey said. “According to our forecast, over the next week, there is a 4% chance of one or more aftershocks that are larger than magnitude 5.1. It is likely that there will be smaller earthquakes over the next week, with magnitude 3 or higher aftershocks.”