USGS reported that a relatively weak earthquake struck central Tennessee earlier today. The quake, which struck at 11am ET, hit near Rockwood, about half way between Knoxville and Nashville at a depth of 13.2 km. The event was classified as a magnitude 2.5 event.
Today’s earthquake occurred in a relative active region of seismicity in Nashville. Western Tennessee is located within the New Madrid Seismic Zone, an area famous for a catastrophic series of earthquakes in 1811-1812 that were centered near New Madrid County, Missouri. The New Madrid Seismic Zone is also known as NMSZ for short.
According to the Missouri Department of Public Safety, the New Madrid Seismic Zone is active and averages about 200 measured events per year (magnitude 1.0 or greater). Tremors large enough to be felt (magnitude 2.5 – 3.0) occur annually. On average every 18 months, the fault releases a shock of magnitude 4.0 or greater, which is capable of local minor damage. A magnitude 5.0 or greater occurs about once per decade, can cause significant damage and be felt in several states.
Earthquakes like the one that occurred earlier today in the central part of Tennessee are unlikely associated with the New Madrid Seismic Zone. However, while USGS says western Tennessee has a higher frequency of damaging earthquake shaking, the risk isn’t that low in central and eastern Tennessee. In the area of today’s earthquake, USGS says its likely this area would see 50-100 damaging earthquakes over 10,000 years. While this number is low, it is much higher than it is elsewhere in the eastern half of the United States, where it’s likely to have 10 or less earthquakes over the same period.