New Madrid Seismic Zone: What to know during Earthquake Awareness Month

JACKSON, Tenn. — February is Earthquake Awareness Month, and the Mid-South sits directly above one of the most active fault systems in the country.

The New Madrid Seismic Zone runs from near New Madrid, Missouri, to Mississippi County, Arkansas, through Southeast Missouri, Western Kentucky, West Tennessee and a portion of Northeast Arkansas. Most of the fault’s activity is concentrated in five counties: Dyer and Lake in Tennessee; New Madrid and Pemiscot in Missouri; and Mississippi County, Arkansas.

How far can a quake be felt?

Earthquakes originating in the central United States can travel across large distances.

“When an earthquake is felt in the central United States, they are felt over vast, vast distances. A couple years ago they had the Mt. Carmel earthquake of southern Illinois, which was, I think, 5.2 on the scale if my memory serves me correct, and it was felt over at least a ten-state area,” said Kent Moran, historian for the Center for Earthquake Research and Information.

What a major quake could mean for the region

FEMA’s Shaken Fury earthquake model from 2019 estimates the potential impacts of a 7.7 magnitude earthquake near Marked Tree, Arkansas. The model is not an earthquake forecasting tool, but rather an estimate of what could occur should a quake strike along the fault. Under that scenario, Tennessee and Arkansas could see damage estimates in the billions of dollars.

“The main effect that causes the loss of life and damage to structures is strong earthquake ground shaking — with the earth shaking so violently many buildings are damaged or completely collapse,” said Walter D. Mooney, seismologist.

How often does the fault shake?

Microseismic quakes of magnitude 2.0 or lower occur along the New Madrid fault roughly every other day. The most recent quake in West Tennessee was a 1.5 magnitude tremor near Ridgely on Friday.

The fault averages seven 3.0 magnitude quakes per year and one 5.0 magnitude quake every decade. The largest earthquake since the 1811–12 sequence was estimated at 6.6 magnitude near Charleston, Missouri, on Oct. 31, 1895.

Scientists remain unsure whether the smaller, ongoing quakes are independent events or aftershocks of the 1811–12 earthquakes.

The nationwide Great ShakeOut earthquake awareness drill is scheduled for 10:15 a.m. Thursday, Oct. 15.

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