Arkansas Earthquake Hazards

Numerous earthquakes occur every year throughout the state of Arkansas, but most go unnoticed. Earthquakes that are felt can be startling, and serve as good reminders that Arkansas is located near one of the most hazardous earthquake zones in the country. Earthquakes have been historically documented in Arkansas, as far back as 1699, by missionaries traveling down the Mississippi River near Helena (Phillips County), Arkansas. Although, it is uncommon for major earthquakes to occur far away from active tectonic boundaries, earthquakes associated with the New Madrid seismic zone (NMSZ), an active earthquake zone extending from Cairo, Illinois, into Marked Tree (Poinsett County), Arkansas, have been some of the largest earthquakes to ever strike North America..

Earthquakes are caused by movement along geologic faults, or fractures in the Earth’s crust. When a fault moves, energy is released and transfers through the earth causing the shaking that is experienced during an earthquake. Arkansas has hundreds, if not thousands of faults. Most of these faults are considered inactive. However, faults associated with the New Madrid seismic zone are active, and deeply buried beneath many layers of unconsolidated sediment and sedimentary rock, making them almost impossible to identify on the Earth’s surface. These faults exist within a failed rift zone, known as the Reelfoot Rift, which developed in the Earth’s crust over 600 million years ago.

On December 16, 1811 residents living in the region near New Madrid, Missouri were jolted awake at 2:15 AM by a major earthquake. Cabins collapsed, people were frightened, and the land surface was severely changed by liquefaction. The shaking was felt as far away as New England and Canada. Scientists estimate that this event measured over a M7.0 (Johnston and Schweig, 1996). This marked the first of a series of powerful earthquakes that spanned a three-month period. Hundreds of aftershocks were reported for over a year.

Since that time, at least 20 damaging earthquakes have occurred in the NMSZ (Nuttli, 1982). An estimated M6.0 earthquake was reported near the town of Marked Tree, Arkansas on January 4, 1843. This earthquake caused the land to subside forming new lakes and did damage to chimneys and brick structures (Jackson, 1979). A M5.0 earthquake was recorded on March 24, 1976 in Poinsett County. This earthquake was felt over an area of 174, 000 sq. miles (280,000 sq. kilometers) bounded by Centralia, Illinois; Hopkinsville, Kentucky; Nashville and Clifton, Tennessee; Birmingham, Alabama; Little Rock, Arkansas; and Jefferson City, Missouri. In Arkansas, multiple cities reported an Intensity VI. Power outages, downed telephone lines in Jonesboro, broken windows in Paragould, cracked plaster in Marked Tree, roof damage and fallen ceiling tile as far away as Decatur, Arkansas (Jackson, 1979).

The most recent events to rattle the residents of northeast Arkansas were felt near the towns of Caraway and Manila, Arkansas in Poinsett County in 2005. Both of these earthquakes registered a M4.1 with an Intensity V. Although significant damage has not been reported in recent years, the NMSZ is still considered active and is potentially capable of generating powerful earthquakes.

The following links provide local and statewide earthquake hazard information:

State Emergency Management Website
https://www.dps.arkansas.gov/emergency-management/adem/plan-prepare/earthquake/

State Geological Survey Website
http://www.geology.arkansas.gov/

USGS State Earthquake Website
https://www.usgs.gov/natural-hazards/earthquake-hazards/science/information-region-arkansas?qt-science_center_objects=0#qt-science_center_objects