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Arkansas' Homeland Security and Disaster Preparedness Agency

Arkansas Department of Emergency Management

To contact us:

Arkansas Department of Emergency Management

Camp Joseph T. Robinson, Building 9501

North Little Rock, AR 72199-9600

Earthquakes

In today’s society, Arkansans think of thunderstorms, floods, and tornadoes as devastating natural disasters, but the Natural State also has the threat of earthquakes to remember.  Most earthquakes are gentle reminders of activity beneath the surface, but in the Northeast part of the state down the Mississippi Alluvial Plain lies the southern portion of the New Madrid Seismic Zone (NMSZ).

Residents living in the NMSZ are not the only citizens that should be preparing for an earthquake.  As shown on the map below, small earthquakes occur across the state.  Due to the soil composition of Northeast and Eastern Arkansas the effects and damages from large magnitude earthquake would be felt for miles.

Seismicity  of Arkansas 1990-2001

Earthquake locations are from the USGS/NEIC PDE catalog.

Three great earthquakes occurred on December 16, 1811 on the southern branch of the fault in eastern Arkansas. The first earthquake which measured magnitude 8.6 occurred at 2:30 am; the second, which was magnitude 8.3 at 8:15 am; and the third, which was magnitude 8.0, at noon. These three earthquakes ruptured the entire southern segment of the New Madrid fault, a length of about 90 miles.

 

On January 23, 1812, an earthquake of magnitude 8.4 ruptured the central segment of the fault, a length of about 45 miles. The largest of the earthquakes, which was a magnitude 8.8, occurred on February 7, 1812, near the town of New Madrid, Missouri. It ruptured the entire northern branch of the fault, a length of about 60 miles. More than 200 additional moderate earthquakes occurred on the New Madrid fault between December 16, 1811, and March 15, 1812.

 

There were also about 1,800 earthquakes with body-wave values of about 3.0 to 4.5. Eighteen of the earthquakes were felt as far away as Washington, D.C.

 

Since 1812, only two large earthquakes of magnitudes greater than 6.0 have occurred in the New Madrid fault zone. The first struck January 4, 1843, centered in Arkansas at the extreme southern end of the fault, at Marked Tree, Arkansas. It had a magnitude of approximately 6.3. The second large, historic earthquake (magnitude of approximately 6.7) with an epicenter at the northern end of the fault (Charleston, Missouri), occurred October 31, 1895.

 

Nuttli, 0tto. W.(1973). The Mississippi Valley Earthquakes of 1811 and 1812: Intensities, Ground Motion and Magnitudes, Bulletin of the Seismological Society of America. Vol. 63, No. 1, pp. 227-248 February 1973