is a shaking or trembling of the crust of the earth, caused by underground
volcanic forces or by breaking and shifting of rock beneath the
Earthquakes are caused by the abrupt release of stored energy within
the earth's crust. These sudden fractions occur when stresses build
up to the breaking point of the breaking point of the rocks miles
beneath the surface in fault zones.
In an earthquake, the actual movement of the ground is seldom the
direct cause of death or injury. Most casualties result from falling
objects and debris from buildings or other structures, which are
damaged or demolished by the earthquake.
Earthquakes also can trigger landslides, cause fires and flooding
and generate massive ocean waves called tsunamis.
Why should I be concerned?
In an average year, dozens of earthquakes will occur in the United
States. Yet most earthquakes, detectable only by sensitive instruments,
will go unnoticed by the general public. Not to be overlooked is
the fact that larger earthquakes can and do occur.
Outside California, the greatest potential for an earthquake in
the United States exists in the seismic zone of the New Madrid Fault
system, which extends some 120 miles through far southeast Missouri
and into northeast Arkansas.
In a five-month period during the winter of 1811-1812, more than
2,000 earthquakes rocked the central United States near the New
Madrid area. Although instruments for measuring them were not available,
at least four earthquakes thought to be among the most intense ever
to occur on this continent happened during this period. Using damage
reports made at the time, experts have estimated the quakes had
a magnitude of 8.0 to 8.8 on the Richter scale. The earthquakes
were felt throughout two-thirds of the continental United States,
from Canada to Mexico and from the Rocky Mountains to the East Coast,
where they rang church bells in Boston.
New Madrid Fault
The New Madrid Fault System extends 120 miles southward from the
area of Charleston, Missouri, and Cairo, Illinois, through New Madrid
and Caruthersville, following Interstate 55 to Blytheville and on
down to Marked Tree, Arkansas. It crosses five state lines and cuts
across the Mississippi River in three places and the Ohio River
in two places.
The fault is active, averaging more than 200 measured events per
year. Earthquakes measuring (1.0 or more on the Richter scale) occur
about 20 per month. Tremors large enough to be felt (2.5 - 3.0 on
the Richter scale) are noted annually. Every 18 months the fault
releases a shock of 4.0 or more, capable of local minor damage.
Magnitudes measuring 5.0 or greater occurring about once per decade,
can do significant damage, and be felt in several states.
The highest earthquake risk in the United States outside the West
Coast is along the New Madrid Fault. Damaging tremors are not as
frequent as in California, but when they occur, the destruction
covers over more than 20 times the area because of underlying geology.
A damaging earthquake in this area, 6.0 or greater, occurs about
every 80 years (the last one in 1895). The results would cause serious
damage to schools and masonry buildings from Memphis to St Louis.
A major earthquake in this area, 7.5 or greater, happens every 200-
300 years (the last one in 1812). There is a 25% chance by 2040.
A New Madrid Fault rupture this size would be felt throughout half
the United States and damage 20 states or more. Missouri alone could
anticipate losses of at least $6 billion from such an event.
How To Ride Out An Earthquake
During a major earthquake, you may experience a shaking that starts
out gently and grows violent…
…or it may begin with a violent jolt – as though your
house was hit by a truck.
Earthquakes give no warning and the majority of earthquakes last
less than 30 seconds so you must be prepared to act quickly!
Most injuries are caused by falling objects and debris. “Duck,
Cover and Hold!” is your best protection. When
the shaking starts, move quickly to the best cover that is available
near you. The longer it takes and the farther you (try to!) move
to get to cover, the higher the risk of injury.
- Duck, Cover, and Hold! where you are.
- DUCK or drop down and take COVER under stable, sturdy furniture,
like a table or desk. HOLD on to it and be prepared to move with
it until the shaking stops.
- If there is no sturdy furniture available, kneel against an
interior wall, bend your head close to your knees, with your arms
and hands protecting your head and neck. Be sure you’re
not directly below heavy wall or ceiling mounted objects.
- Avoid tall, unstable, furniture, like bookshelves, file cabinets,
or entertainment centers.
- Move away from windows, or at least turn your back toward them.
During earthquakes, windows have shattered with enough force to
damage wood and tile.
- Do not try to run outside or move to a different floor! Be prepared
for electricity to fail, and alarms or sprinkler systems to go
- Additional tips for specific locations:
- Move away from the refrigerator, stove, and overhead
cupboards. If possible, turn off burners. (Take time NOW
to anchor appliances, and install security latches on
cupboard doors to reduce hazards.)
- High-rise buildings
- If there is no desk or table nearby, move against an
interior wall and protect your head with your arms. Do
not use the elevators. Stay indoors. Glass windows can
dislodge during the quake and sail for hundreds of feet.
- Crowded store or other public places
- Do not rush for exits. Move away from display shelves
containing objects that could fall.
- Stadium or Theater
- Stay in your seat, get below the level of the back of
the seat, and protect your head with your arms. Do not
try to leave until the shaking is over. Then leave in
a calm, orderly manner. Avoid rushing toward exits.
- If you're in a Wheelchair, stay in it. Move to cover,
if possible, lock your wheels, and protect your head with
- Mobile homes
- During earthquakes, in addition to falling debris, many
mobile homes are knocked from their pedestals, rupturing
utility connections and forcing pedestals up through the
floors. The best option may be on top of a bed, couch,
or other sturdy furniture while protecting your head from
During an earthquake, the areas near building exteriors can be
deadly. Many injuries occur when people trying to exit buildings
are caught in a rain of falling glass, bricks and building parts.
- Move clear of building exteriors.
- Check for overhead hazards such as power lines or utility poles.
- Kneel down and wait for the shaking to stop. Stay alert for
other dangers that may require movement.
- Operating Motor Vehicles
- Pull clear of traffic as far as possible and stop.
- If possible, avoid stopping on or under overpasses or bridges.
Also avoid stopping under other overhead hazards such as power
lines, light posts, or traffic signals.
- Stay in your vehicle and set the emergency break.
- When shaking stops, evaluate your surroundings and proceed
with caution. Be alert for emergency vehicles.
After The Earthquake
- Remain calm. Take a deep breath and evaluate
what has happened around you. Be prepared for aftershocks.
- Do NOT use elevators
- Tune your radio to the local Emergency Alert Station
(KMOX) 1120 AM (KWRE) 730 AM for the latest information
and assistance available.
- Check for injuries. Do not attempt to move seriously
injured persons unless they are in immediate danger of further
- Wear sturdy shoes to protect your feet from fallen glass.
- Check gas, water and electrical lines and appliances for damage.
If you smell gas or see a broken line, shut off the main valve
(outside the house). Do not switch on the gas or electricity again
until the power company checks your home (this could take days
or weeks, depending on the extent of damages). It would be best
to find shelter else where. Also know where the main shut offs
are for water and electric.
- Use flashlights only for light source! Do not
light matches or use any open flames, i.e. candles.
- If there's a fire and you can fight it without getting hurt,
put it out with the proper extinguisher. Do not use water
on electrical or gas fires.
- Assume downed power lines are carrying live current and avoid
- Do not use the telephone. It must be reserved for life-or-death
situations. (Long distance service (pay Phone) may be on sooner
than local, if you have family or friends outside the state (as
far away as possible) make sure that each family member has that
number and use it as the point of contact to check on each other
if your family has been separated.
- Check to see that sewage lines are intact before you use the
toilet. Plug bathtub and sink drains to prevent sewage backup.
Missourians Prepare in Case of an Earthquake