EXCLUSIVE: Arkansas located on a major, and active seismic zone

News

Photo Courtesy: United States Geological Survey

ARKANSAS (KNWA) — As earthquakes rumble parts of California and are shown on media outlets across the nation, Arkansans must not forget that the most active seismic zone east of the Rockies runs through part of the state.

This seismic zone zigzags through Arkansas, Missouri, Tennessee, Kentucky and Illinois, according to the United States Geological Survey (USGS).

“Geographically, it is approximately 185 miles long and, 43 miles wide, and runs to the northeast-southwest,” said Geohazards Supervisor Martha Kopper with Arkansas Geological Survey.

Earthquakes, which are caused by the release of strain along a fault plane, can’t be predicted.

“There are no warning signs … however smaller earthquakes precede large earthquakes…,” Kopper said.

Small and moderate earthquakes continue along the New Madrid Seismic Zone. About 200 earthquakes happen annually along this seismic zone, however, most are too small to be felt, according to the USGS. ­­­

In Arkansas, at least 15 earthquakes have been reported within the past six months, and one within the past week, according to the University of Memphis Center for Earthquake Resarch and Information.

All Arkansans would be impacted in some way if a high-magnitude earthquake happened like in California.

“Everyone will be impacted in one way or another, whether they need to visit an uncle who lives in West Memphis, have business packages going to Atlanta – shipped via FedEx out of Memphis, play in softball tournaments in Jonesboro or live in Forrest City, Ark.,” Kopper explained. “Those injured, or living or working will be moved out of the impact damaged area and will be relocated to other areas of the state not impacted.”

The impact of the quakes in California won’t disrupt Arkansas because of distance and because the geology is different.

“The July 4th event (California) was preceded by a short series of small fore-shocks including a magnitude 4.0 earthquake 30 minutes prior,” Kopper explained. “… It was followed by a robust sequence of aftershocks including almost 250 magnitude 2.5 and higher earthquakes up until the magnitude 7.1 event.”

However, lessons and practices can be learned from the disasters in California, as many in that state weren’t prepared for earthquakes of such high magnitudes.

“That is what our agency (Arkansas Geological Survey) does along with the Arkansas Department of Emergency Management,” Kopper said.

These agencies are established to educate Arkansans, promote safety and address concerns.

Continuing Concerns

Scientists agree that there is a continuing concern for a major earthquake in the New Madrid Seismic Zone. Many structures would be damaged. Decades of research conducted by federal, state, university and scientists back this claim, according to USGS.

The USGS predicts there is a chance of having an earthquake similar to the one of the 1811 and 1812 sequence within the next 50 years. If so, Arkansans should know what to expect.

What to expect

Earthquakes that have magnitudes of 6.0 to about 7.7 have energy equivalents of the Hiroshima Atomic Bombing. Earthquakes that have magnitudes of 7.8 to about 8.0 have energy equivalents of the Mount St. Helens eruption.

Energy equivalents of magnitude 8.1 to about 8.5 are the world’s largest nuclear test, which was the USSR. Magnitude 8.5 and higher quakes have energy equivalents of the Krakatoa volcanic eruption.

Ground failures including landslides, soil liquefaction, lateral spreading, demolished infrastructures, disrupted agriculture and farmland, impacts to river navigation would occur, Kopper explained. Fires and flooding would also be expected.

Koppper added there would be a significant social impact.

More than 1 million residents in Memphis, Tenn. and surrounding metropolitan areas would be severely impacted, the USGS states.

In that city, the old infrastructures, schools and offices and other structures built without proper building codes are issues. The city is the focus of major damage in the region, but those in Little Rock will also sustain damage.

From the recent events in California, lessons can be learned for when a large magnitude earthquake strikes again in the Natural State. Many California residents weren’t properly prepared.

Many are displaced. There are many ways to prepare.

How to prepare

If an earthquake is felt, remember to drop, cover and hold, according to the University of Memphis Center for Earthquake Research and Information.

The Center for Earthquake Research and Information (CERI) suggests having an earthquake survival kit handy. Those kits include items typically found in a first-aid kit, water, canned foods or ready-to-eat meals, a can opener, medication, batteries, and portable radios, a fire extinguisher, flashlight, and clock or watch, according to the University of Memphis Center for Earthquake Research and Information.

Those with pets should also consider their needs.
Safe shoes, gloves, candles, matches, knives, garden hoses, and tools are also encouraged.

CERI also suggests knowing how to turn off gas, water, and electricity. Anchoring heavy objects to walls and doing away with heavy objects over beds are necessary precautions.

Lastly, cities must enforce proper building codes, according to USGS.

Find more information, here.

Historical Accounts

During spring of 1976, a magnitude 5.0 earthquake happened in Poinsett County, Ark. People within 174,000 square-miles felt the quake and substantial damage occurred.

An earthquake estimated at a magnitude of 6.0 happened near Marked Tree, Ark. during 1843.

Three major earthquakes rocked the New Madrid region during 1811 and 1812. The first happened Dec. 16, near present-day Blytheville, Ark. It’s estimated to be a magnitude of 7.7 and was so large, it woke people 900 miles away. The damage was reported 300 miles away, according to USGS.
The second major quake happened Jan. 23, and damaged an area of more than 232,000 square-miles.

The third happened Feb. 7 and was estimated to be a magnitude of 7.7.
Reports state the Mississippi River flowed backward.

In 1814, the first Disaster Relief Act was passed in the U.S. Congress and allocated $50,000 for recovery during 1815, according to USGS.
Geologic records before 1811 describe repeated, major earthquakes along the New Madrid Seismic Zone. Several earthquakes of magnitude 7 and 8 happened, and completely changed the earth’s surface.

Misconception

Some think that due to the lack of strain at the seismic zone, there is no buildup of stress within the New Madrid Seismic Zone, and that there is no longer a significant threat of this zone, the USGS states. However, experts with USGS evaluated debunked this misconception.

Copyright 2019 Nexstar Broadcasting, Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

Don't Miss