Indiana Experts Wary Of Earthquake Swarm

Hundreds Of Tremors Rattle Arkansas For Unknown Reason

Indiana scientists are keeping a wary eye on a series of earthquakes that has been rattling Arkansas for days.

More than 60 tremors struck the state last week, a phenomenon that's almost becoming a daily routing for residents there, 6News' Stacia Matthews reported.

A half-dozen quakes shook one Arkansas community on Monday morning, with more than 700 recorded in Faulkner County, Arkansas within the past six months. Although most of the tremors are too small to be felt by humans, experts across the Midwest are trying to find out why they are occurring.

"This is absolutely a phenomenon, an interest to seismologists in this part of the country," said Michael Hamburger, a professor of geological sciences at Indiana University. "We're all trying to make sense of it."

Hamburger and other experts refer to the string of tremors as a swarm.

"This is a slow, developing swarm of activity, starts with some fairly small earthquakes," he said. "The size gradually increases, and there are many of a similar size, and they die down within a few weeks, a few months time."

The quakes aren't of direct concern to Indiana, because they are not along the New Madrid zone, which is the focus of seismic activity in the state.

Some experts have speculated that the quakes might be related to natural gas injection wells in the area. Gas is freed by drilling pressurized water into the ground.

Hamburger said Indiana's biggest seismic concern is the possibility of a repeat of the devastating earthquakes that affected the region in 1811 and 1812.