Searching for Louisa’s faults

Posted on Monday, January 20, 2014 at 9:00 am

Seismologists placed 20 seismometers in and around Louisa County. Equipment included digitizers, solar panel charge controllers and GPS receivers.

Seismologists placed 20 seismometers in and around Louisa County. Equipment included digitizers, solar panel charge controllers and GPS receivers.

Every Louisa local remembers where they were on August 23, 2011. That’s when the infamous, 5.8 magnitude Mineral Earthquake shook the region and caused more than $80 million in damages in Louisa County alone.

We know what happened. Now, researchers are trying to find out why.

Seismologists from Virginia Tech and the U.S. Geological Survey are joining forces to conduct a two-month study of seismic activity in the region. Researchers will be studying what is specifically called the 3,000-square-mile area known as the “Central Virginia Seismic Zone” by planting 20 electromagnetic receivers across Louisa and in six other surrounding counties.

“I’ve been wanting to do this for a very long time,” project manager and Virginia Tech seismologist professor Martin Chapman said. “I’ve been studying the Central Virginia Seismic Zone since the 1970’s. This was an opportunity to put a relatively dense array of seismographs and operate them for a brief period of time. We certainly expect to see a lot of small earthquakes.”

The sensors, which are buried about a foot underground, are about the size of a soft-drink can and collect critical data of ongoing seismic activity in the area. According to the U.S.G.S., there have been at least 450 aftershocks since the 2011 Mineral Earthquake, most of which are undetectable by humans. By having more sensors, researchers are hoping to better locate fault lines where the activity is occurring.

“The object here is that if we can record a lot more earthquakes, then we might be able to figure out what faults they’re on and what’s causing them, to some extent,” U.S.G.S research geophysicist Thomas Pratt said.

Pratt, Chapman and a group of fellow researchers installed the sensors from Jan. 9 to Jan. 14. Research teams will periodically return to the sites to download data from them before removing the sensors sometime in late March or early April.

Before the project, Chapman and Pratt said they knew of only two or three sensors, called seismometers, planted in the area. The lack of data originating from the area created a problem for geologists looking to study earthquake behavior in the area.

To read the entire story, see the Jan. 16 edition of The Central Virginian.

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