Earthquake


There are three yellow areas that impact Georgia on the map to the right. The one at the west end of Tennessee, part of Arkansas, and Missouri is called the New Madrid Fault, second is a area centered around Charlestown, S.C. and a third that runs along  the Appalachians in North Carolina and Tennessee.  To anticipate the need, we must first look to the past.   

Massive New Madrid Earthquake (8.3)  The 400 terrified residents in the town of New Madrid (Missouri) were abruptly awakened by violent shaking and a tremendous roar. It was December 16, 1811, and a powerful earthquake had just struck. This was the first of three magnitude-8 earthquakes and thousand of aftershocks to rock the region that winter.

USGS map  

  

Survivors reported that the earthquakes caused cracks to open in the earth's surface, the ground to roll in visible waves, and large areas of land to sink or rise. By winter's end, few houses within 250 miles of the Mississippi River town of New Madrid (Missouri) remained undamaged. The crew of the New Orleans (the first steamboat on the Mississippi, which was on her maiden voyage) reported mooring to an island. Then, in the wee hours, the boat was nearly swamped by a series of enormous waves. As the deck pitched and yawed, the crew and the few passengers on board held on for their lives. Later, one of the crew said it was like being in the middle of an ocean during a violent storm.

All along the riverbank, high bluffs crumbled into the water. Seemingly solid ground undulated in waves. Old river channels slammed shut and new ones opened, changing the course of the stream forever. One large lake had its water suddenly replaced by sand. Another lake, Reelfoot, was created in a matter of moments.

Trees toppled or were drowned when the land sank suddenly beneath them. Log cabins scattered like match sticks in New Madrid but, luckily, only one person was killed by falling debris.  Damage was reported as far away as Augusta, GA and Washington, D.C.

Charleston Earthquake (7.3) On August 31, 1886, just before 10:00 PM, there was a slightly tremor which quickly grew to a roar.  Few buildings escaped damaged and many chimneys collapsed.  The death rate was about 60 and hundreds were injured. Both Augusta and Savannah experienced damage as well.  The epicenter was along the Ashley River and Woodstock faults.

Although earthquakes in the central and eastern United States are less frequent than in the western United States, they affect much larger areas. This is shown by two areas affected by earthquakes of similar magnitude-the 1895 Charleston, Missouri, earthquake in the New Madrid seismic zone and the 1994 Northridge, California, earthquake. Red indicates minor to major damage to buildings and their contents. Yellow indicates shaking felt, but little or no damage to objects, such as dishes.

Earthquakes in the central or eastern United States affect much larger areas than earthquakes of similar magnitude in the western United States. For example, the San Francisco, California, earthquake of 1906 (magnitude 7.8) was felt 350 miles away in the middle of Nevada,

 whereas the New Madrid earthquake of December 1811 (magnitude 8.0) rang church bells in Boston, Massachusetts, 1,000 miles away. Differences in geology east and west of the Rocky Mountains cause this strong contrast.  

There is a intensive earthquake awareness program in Tennessee, Arkansas, and Missouri to rebuild buildings to earthquake codes, modify bridges and roadways, and a elementary school earthquake education program to prepare residents for what may happen.  In the last five year, there has been new earthquake activity in the region.  

Georgia Natural Map

Georgia Seismic Hazard Map

Seismic Hazard Map

 

The chances of a catastrophic Mid-South earthquake in the lifetime of most people now living is slight, but if it happens, it would devastate the region.

"It's a low-probability, high-consequence hazard," said Jim Wilkinson, director of the Central U.S. Earthquake Center, to a group of scientists, emergency management professionals and others at the Oxford Conference Center on Tuesday. "We don't expect it to happen tomorrow, but when it does, I don't think we're prepared for that."

Oliver Boyd, a seismologist with the U.S. Geological Survey, said a 7.7 quake in the Missouri Boot heel "would give severe damage almost to Memphis, heavy damage through much of northern Mississippi."

He estimated the 50-year chances of seismic disturbances equaling the quakes of 1811-12 that made the Mississippi River flow backward is 7 to 10 percent. A 6.0 quake on the Richter scale, which could produce significant damage in eight states, including Mississippi and Alabama, has a 25- to 40-percent likelihood in the same period, he said. A New Madrid earthquake potentially is more devastating than a California-style quake of the same strength because buildings are less resistant and seismic activity would travel farther, making rescue and rebuilding more difficult.

"This would be spread over 20 times the area that the 1994 Los Angeles earthquake covered," Wilkinson said.

Emergency management agencies, university consortia and other entities are forming estimates of potential quake damage and plans for recovery. Such plans include shelter, food, water and medical help; emergency communications and transportation; security; and eventual restoration of infrastructure.

Although earthquakes are uncommon in this area, tremors occasionally occur and residents should be prepared. Identify safe places in each room of your home. A safe place can be under a solid piece of furniture and away from windows, hanging objects or tall furniture that could fall on you. Note that after an earthquake your utilities may be disrupted. Learn how to shut off the source of natural gas to your home if you smell a leak.