EARTHQUAKES COMMON HERE, BUT NOT THE BIG ONE YET

Southeast Missourians are no strangers to earthquakes. They occur almost daily, but most aren't felt except by sensitive instruments able to measure even the slightest ground movement.

The last earthquake of sufficient magnitude to be felt in the region was on Feb. 5 last year, when a mild quake was centered in Lick Creek, Ill., eight miles south of Carbondale.

That earthquake was 4.2 on the Richter scale, which measures an earthquake's intensity and the amount of energy it releases. The quake that struck Kobe, Japan, this week, measured 7.2.

Seismologist Dr. David Stewart said that is 32,000 times more powerful than the Lick Creek quake.

The only destruction from the Southern Illinois quake last year was $20,000 in damage to a brick home eight miles south of Lick Creek.

But more than 20,000 buildings were destroyed in the Japan disaster, a testament to the earthquake's stunning intensity.

"If the same kind of earthquake that hit Kobe happened in the Midwest, it would have affected buildings in a 250-mile radius," Stewart said.

Kobe is a city of 1.4 million people. Tokyo, which is 280 miles from Kobe, was unaffected.

The largest earthquake to hit the Midwest in the last 30 years was in 1968 and registered 5.5 on the Richter scale.

"The reason that Tokyo wasn't hit is liquefaction," Stewart said. Liquefaction turns the soil into quicksand. "Everything just sinks as the ground turns to liquid," Stewart said.

"When you have sandy soil located near rivers, the ground is so unstable that building construction can't deal with it," he said. "A smaller area is affected but the damage becomes much more extensive."

Because Kobe, a port city, is so heavily populated, the death toll would be much more significant than in the Midwest. By Wednesday, the death count in the Kobe area was at 3,021. At least 14,572 people were hurt and 869 were listed as missing.

Stewart said the wave of the future for construction methods will be similar to the ones used in New Madrid.

"When they built the electric plant in New Madrid, they dug wells and filled them with coarse gravel to make the ground under the building more solid," he said. "It's an expensive procedure, but not nearly as costly as losing the building."

Most of Cape Girardeau's geological makeup of bedrock is the most solid base to build on, Stewart said, adding that from Benton south to the Gulf of Mexico the land has little bedrock.

A publication titled "Damages & Losses From Future New Madrid Earthquakes" says the central United States is long overdue for another earthquake of 6.3 magnitude. The booklet is available at the Southeast Missouri State Earthquake Center.

"The interval for repeating is from 55 to 85, years and it's been more than 99 years since we've had one of 6.3 in the Midwest," Stewart said. "Looking at that scale, it looks like we're long overdue."

The publication reveals the probability of an earthquake that registers 6.3 on the Richter scale is 50 percent for the next 15 years and 90 percent for the next 50 years.

Probability is based on geologic evidence found in soils and rocks from which information of previous large earthquakes can be determined.