Local geologist comments on recent West Tennessee earthquake

MARTIN, Tenn. — Wednesday morning wasn’t West Tennessee’s first shake up.

The New Madrid Fault Line runs from Illinois, through Missouri, into West Tennessee and ends in Arkansas.

“The New Madrid Fault is actually a story that goes back about 750 million years, when the North American crust tried to tear itself apart, but didn’t really finish the job, so it basically left a scar in the earth’s crust,” UT Martin professor of geology Angie Van Boening said.

Earthquakes happen because of tectonic plate activity.

However, fault lines can be located further inland on tectonic plates.

“When you have the plates moving, all of the stresses kind of build up along those scars, and so every once in a while you’ll have an earthquake that comes through along those places,” Van Boening said.

Significant earthquakes don’t happen as often along the New Madrid Fault as they do on the San Andreas fault in California.

Smaller earthquakes are more common for West Tennessee.

The last major earthquakes took place between 1811 and 1812. Van Boening says those earthquakes ranged from a 7 to over an 8 in magnitude.

“When those happened, it did cause the Mississippi River to flow backwards at times and shift out of its banks, and so the Reelfoot Lake was created when it basically went through one of the earthquakes, kind of shifting the river and leaving behind a bend in the river, and so now it’s a lake, rather than still being connected to the Mississippi,” Van Boening said.

In geological age, Reelfoot Lake is considered to be very young.

Earthquakes are measured from 1 to 10 on the Richter scale, and scientists use different tools to measure their magnitude.

Van Boening says there is about a 7 to 10 percent chance of another large earthquake over the next 50 years.