An earthquake 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 surface.
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.
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.
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.
…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 off.
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.)
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 your arms.
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 falling debris.
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 injury.
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 all contact.
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.