School Delays across the Tennessee Valley

Could large quake rock Alabama in the near future?

Data pix.

HUNTSVILLE, Ala - Did you feel it? There was an earthquake 11 miles outside of Huntsville Sunday night. It was small, only measuring 2.5 on the Richter scale.

But scientists say there could be larger quakes on the way.

People normally associate earthquakes with California, especially after large quakes that caused damage earlier this month. However, officials with the Alabama Geological Survey say there are 10-20 earthquakes people can feel in Alabama every year.

New Madrid Seismic Zone

The New Madrid seismic zone is located in parts of Illinois, Missouri, Arkansas, Tennessee, and Kentucky. But earthquakes in that zone can cause shaking in Alabama.  Back in 1812, a 7.7 magnitude earthquake was observed in this area.

"There's wive tales about Mississippi and flowing backward for a few weeks," said Brian Hastings, Alabama EMA director.

Hastings says scientists predict quakes of that magnitude in the New Madrid zone once every 200 years.

"A large quake has about a 25% to 40% chance of being a 6.0 magnitude or greater in the next 50 years," he said.

None of the NMSZ fault lines extend into Alabama. However, when the quake occurs, Hastings says infrastructure in northwest Alabama could be affected, specifically mentioning roads and bridges.

Southern Appalachian Seismic Zone

Sandy Ebersole is the Geological Investigations Program Director for the Alabama Geological Survey. She says the fault lines that run through North Alabama are part of the Southern Appalachian seismic zone.

Several fault lines in the SASZ criss-cross in Alabama.

The largest earthquake recorded in Alabama was in the Birmingham area in 1916. It was a 5.1 magnitude earthquake. As recently as 2003 a 4.3 magnitude earthquake rocked the Fort Payne area.

Ebersole says scientists estimate 4.0-5.5 magnitude earthquakes occur once every few decades in this zone. Most earthquakes that center in Alabama are between a magnitude of  2.0-3.5 on the Ritcher scale.

Preparing For Large Quakes

TVA is currently reinforcing the Pickwick Dam.

"The new Madrid fault its not uncommon for people have predicted an 8 on the Richter scale so what we're doing at Pickwick is reinforcing that dam, the earth, and embankment to withstand an earthquake of that magnitude," said Scott Fiedler, TVA spokesperson.

He says that job is requiring quite a bit of material.

"What we're doing is moving over a million tons of material along the earthen embankment part of the dam and that's equivalent to about 305 Saturn rockets."

On top of that, TVA has an inspection schedule for the browns ferry nuclear plant and other dams in north Alabama to ensure the facilities could stand a large earthquake.

"We take earthquake safety very seriously. We have a robust system. We monitor our facilities every month at our dams, and every 15 months we have a higher level inspection, and every five years we have a really deep dive," he said.

 

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