A researcher at the University of Arkansas says recent research showing a build-up of strain in the New Madrid Seismic Zone is inconclusive because the tension can't be seen well enough to determine any earthquake hazard.

In a letter that appeared in the journal Nature, Glen Mattioli, professor of geosciences at the J. William Fulbright College of Arts and Sciences, calls for more research to determine the earthquake potential in seismic zone.

Mattioli re-examined data collected by a research group at the Center of Earthquake Research and Information at University of Memphis. That data showed the strain present in the New Madrid area as a type that generally causes earthquakes.

[The New Madrid zone overlies a weak area in the North American continental plate. Four of the largest earthquakes recorded in the continental United States shook the area from Dec. 1811 to Feb. 1812, with the last one ringing church bells in Boston.]

"Our conclusion was that there may be some deformation going on in the New Madrid Seismic Zone, but if there is, it's close to or below the level of detectability," Mattioli said.

Mattioli said both groups of researchers agree that enhancing the current research tools may help develop a clearer picture of what is occurring, and why earthquakes happen in the area.

Mattioli said the earthquakes in the New Madrid Zone occur differently than those along other fault lines.

"This whole thing is a big enigma," Mattioli said. "As far as we know, the reason we get earthquakes is because of applied stress related to the motion of plates."

But Mattioli said that reason doesn't apply along the New Madrid Fault. No theory has fully explained why large earthquakes may have occurred there, either, he said.

Additionally, the Mississippi River basin complicates earthquake study because shifting sand and mud make it difficult to isolate movements, he said.

Mattioli has proposed creating a larger network of stations to produce computer generated data that will help better determine what is happening in the area.

"In the long run, this may give the U.S. Geological Service a way to assess earthquake hazard in continental interiors where earthquakes and their cycles are not very well understood," he said.