M 3.8 - 2 km NE of Fincastle, Tennessee

Tectonic Summary

A pair of earthquakes struck the Fincastle, TN area north of Knoxville over the Martin Luther King Day weekend and included a magnitude 2.8 at about 5:19 AM EST Sunday morning, January 19, 2020 followed by a magnitude 3.8 at about 1:12 PM EST Monday afternoon. These earthquakes occurred in an area known as the East Tennessee Seismic Zone (ETSZ). The ETSZ extends in a ~250 km long band that parallels the southern Appalachian Mountains from northeast Alabama though Tennessee to southwest Virginia and possibly northeast Kentucky. The earthquakes occur at depths far below the surface mountains and may be associated with a major transform fault (like the San Andreas fault) that was active over a billion years ago. The reason why the earthquakes occur is unknown. Leading theories suggest increased buoyancy in the crust or elevated surface erosion. The largest recent earthquake was a magnitude 4.6 earthquake near Fort Payne, AL on April 29, 2003. With about 70-100 events recorded annually (nearly all too small to be felt), the ETSZ is the second most active region of naturally occurring seismicity in the eastern U.S. (New Madrid being the most active). It is an intraplate seismic zone making the source of the seismicity an active area of research.