|
 |
There
are three yellow areas that impact Georgia on the map to the
left.. 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. |
|
Tectonic
Activity Map (DTAM)
|
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
|
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. Check the menu at the right for more
information.
|
