Quake demonstrates volatility of New Madrid fault

Just one day after a group of officials visited Cape Girardeau to discuss the risks of earthquakes in the area, an early-morning quake centered in Tennessee shook much of Southeast Missouri.

The magnitude 4 earthquake occurred at about 6:35 a.m. Thursday about 10 miles outside of Dyersburg, Tenn., according to information released by the State Emergency Management Agency. The quake reportedly did not cause any injuries or damages, but it was felt by residents in several Missouri counties, including Cape Girardeau, Scott and Bollinger.

Joan Gomberg, a seismologist with the U.S. Geological Survey, said more than 800 people reported feeling the earthquake on the U.S. Geological Survey's "Did You Feel It" Web site, and some of them were from as far away as Memphis. Gomberg said magnitude 4 earthquakes can be felt by people over large areas but usually do not cause extensive damage.

"If you're very close by, it could cause things to fall off the shelves, but unless it's a very shallow earthquake, it would be somewhat unusual to cause walls to crack or things like that," Gomberg said.

Seismologists expect earthquakes of similar magnitudes to occur along the New Madrid fault every two to five years, but Gomberg said three quakes in the 4 range have rattled the area in the last couple of months.

Happens everyday

Gomberg said the fault is always shifting, even when large earthquakes don't occur.

"Little ones happen there everyday, but much of them are too small to be felt," Gomberg said.

The U.S. Geological Survey recorded one small aftershock, which Gomberg said fell between magnitude 1 and 2. Aftershocks, or smaller tremors that follow a large earthquake, are not uncommon, Gomberg said.

"Any earthquake is certainly capable of generating aftershocks and most earthquakes do, although not all do," she said.

If an earthquake occurs, the State Emergency Management Agency recommends that one should drop to the ground, find cover and hold on. Families should teach children about proper earthquake safety procedures and designate safe spots in every room of the house. For more information about earthquakes and earthquake safety, visit the SEMA Web site at sema.dps.mo.gov/EQ.htm.

wmcferron@semissourian.com