MARKED TREE, Ark. (AP) ? Scientists planned underground explosions Monday and Tuesday nights to generate artificial earthquakes and determine where damage might be the worst after a major temblor on the New Madrid Fault.

?By causing our own earthquake, we know exactly how big it is, where it is, and all the instruments here will be very useful for us,? said Eugene Schweig of the U.S. Geological Survey, showing off gear to track seismic waves rolling through the soft Delta soil.

Setting off 2,600 pounds of ammonium nitrate near Marked Tree late Monday or early Tuesday will mimic an earthquake of magnitude 2.0. Quakes of that magnitude are often not felt.

?We need to figure out how hard the ground is and what it means to earthquake waves that are going through it,? said Chuck Langston, a professor of seismology at the University of Memphis, which also is involved in the study.

Another explosion, of 5,000 pounds of ammonium nitrate, is scheduled for overnight Tuesday near Mooring, Tenn.

Marked Tree is near the southern end of the New Madrid Fault Zone which runs into southern Illinois and southwestern Indiana.

Six scientists trudged through a muddy field Monday, laying out sensors in a line to track ground movement after the explosion that will be set off 160 feet below ground level.

?The waves will go out from the blast and sweep across these sensors,? Langston said. ?The (sensors) will tell us how seismic waves move.?

The researchers say people living within a few miles of the explosion might feel a tremor, though the explosions won?t be big enough to damage anything.

?Every piece of equipment will be recording hundreds of pieces of information every minute,? Schweig said. Also, 80 permanent and 10 new sensors elsewhere in the New Madrid zone will ?listen? for activity.

With the information gathered at Marked Tree and Mooring, civil authorities will have tools to direct assistance to places hardest hit by an earthquake.

?Out West, they have a ?ShakeMap? ... an instrument that creates a map within moments of a quake? to show areas hardest hit, Schweig said. ?This experiment will help us figure out ... how long a quake will last, where the shake will occur, where it will shake most.?

The experiment was planned for overnight to reduce interference from activities such as traffic, livestock movement and pump vibrations on farms.

A series of strong quakes occurred along the New Madrid Fault in 1811-1812. One was so powerful it caused the Mississippi River to flow backward and was said to ring church bells on the East Coast.