Lincoln County Missouri Government

EARTHQUAKES

The potential for earthquakes in Missouri always exists. Family earthquake preparedness and what family members do during and immediately after the tremor can help minimize damage and may make a life-or-death difference. With advance preparation, the impact of an earthquake can definitely be lessened. Set aside some emergency supplies and plan with your family what to do at home during and after a disaster. You may not get help for up to 72 hours, so you'll need to learn to cope with the situation for at least that long and possibly one week.

Movement of the ground is seldom the actual cause of death or injury. Most injuries and casualties result from partial building collapses, falling objects and debris, such as toppling chimneys, falling bricks, ceiling plaster, and light fixtures.

PREPARATION SAVES LIVES

Because earthquakes occur without warning it is important to be prepared by having a home emergency supply kit available. The kit should include:

Flashlights with extra batteries - One of these flashlights should be near your bed. Never use matches or candles until you are certain no gas leak exists.
Portable radio with spare batteries - Most telephones will be out of order or should be used for emergency purposes only, so the radio will be your best source of information.
Well-stocked first aid kit and handbook - Every member of the family should have basic first aid knowledge and be competent in CPR.
Fire extinguisher - Keep a multi-purpose dry chemical extinguisher handy for small fires. Every family member should know where it is and how to use it.
Food - Keep a supply of non-perishable food on hand that can be rotated into the family's diet and replaced on a regular basis. Have enough canned foods, a mechanical can opener, powdered milk and/or canned juices for a least one week. Dried cereals, fruit, and non-salted nuts are a good source of emergency nutrition.
Water - Store water in airtight containers and replace it about every six months. Store at least six gallons of water per person to be prepared for a one-week period.
Special items - Have at least one week's supply of medications and special foods needed for infants or those on limited diets.
Tools - Pipe wrench and adjustable wrenches should be available for turning off gas and water mains. Family members should be taught where and how to shut off electricity, gas, and water at the main or main switch.

STAYING CALM IS VERY IMPORTANT

If you are indoors, stay there. Take cover under a heavy desk, table, or bench in a supported doorway or along an inside wall. Stay away from windows, bookcases, china cabinets, mirrors, and fireplaces until the shaking stops.

If you are in your car, pull to the side of the road and stop the car. Do not park under overpasses or power lines. Stay in your car until the earthquake is over. When you drive on, watch for hazards created by the earthquake, such as fallen or falling objects; downed electric wires; damaged, broken or undermined bridges, roadways or overpasses.

A bit of trivia for your information:

The Richter magnitude scale is commonly used but often misunderstood. Each whole-number step of magnitude represents a tenfold increase in amplitude. Therefore, the amplitude of an 8.6 magnitude earthquake is not twice that of a magnitude 4.3 quake, but rather 10,000 times as large. Trying to understand the relative increase in magnitude might be understood by expressing a magnitude 1 as roughly proportional to the size of a small marble, a 2 to the size of a golf ball, a 3 to the size of a grapefruit, and a 4 to the size of a basketball. At the same scale, the energy release by an earthquake of a magnitude 8.7 could be represented by a sphere the size of a hot air balloon.

EARTHQUAKE INTENSITY

Another means of trying to bring meaning to the intensity of an earthquake is the Modified Mercalli Intensity Scale

MODIFIED MERCALLI INTENSITY SCALE

I People do not feel any earth movement.

II A few people might notice movement.

III Many people indoors feel movement.

IV Most people indoors feel movement. Dishes, windows, and doors rattle. Walls and frames of structures creak. Liquids in open vessels are slightly disturbed. Parked cars rock.

V Almost everyone feels movement. Most people are awakened. Doors swing open or closed. Dishes are broken. Pictures on the wall move. Windows crack in some cases. Small objects move or are turned over. Liquids might spill out of open containers.

VI Everyone feels movement. Poorly built buildings are damaged slightly. Considerable quantities of dishes and glassware, and some windows are broken. People have trouble walking. Pictures fall off walls. Objects fall from shelves. Plaster in walls might crack. Some furniture is overturned. Small bells in churches, chapels, and schools ring.

VII People have difficulty standing. Considerable damage in poorly built or badly designed buildings, adobe houses, old walls, spires and others. Damage is slight to moderate in well-built buildings. Numerous windows are broken. Weak chimneys break at roof lines. Cornices from towers and high buildings fall. Loose bricks fall from buildings. Heavy furniture is overturned and damaged. Some sand and gravel stream banks cave in.

VIII Drivers have trouble steering. Poorly built structures suffer severe damage. Ordinary substantial buildings partially collapse. Damage slight in structures especially built to withstand earthquakes. Tree branches break. Houses not bolted down might shift on their foundations. Tall structures such as towers and chimneys might twist and fall. Temporary or permanent changes in springs and wells. Sand and mud is ejected in small amounts.

IX Most buildings suffer damage. Houses that are not bolted down move off their foundations. Some underground pipes are broken. the ground cracks conspicuously. Reservoirs suffer severe damage.

X Well-built wooden structures are severely damaged and some destroyed. Most masonry and frame structures are destroyed, including their foundations. Some bridges are destroyed. Dams are seriously damaged. Large landslides occur. Water is thrown on the banks of canals, rivers, and lakes. Railroad tracks are bent slightly. Cracks are opened in cement pavements and asphalt road surfaces.

XI Few if any masonry structures remain standing. Large, well-built bridges are destroyed. Wood frame structures are severely damaged, especially near epicenters. Buried pipelines are rendered completely useless. Railroad tracks are badly bent. Water mixed with sand and mud is ejected in large amounts.

XII Damage is total, and nearly all works of construction are damaged greatly or destroyed. Objects are thrown into the air. the ground moves in waves or ripples. Large amounts of rock may move. Lakes are dammed, waterfalls formed, and rivers are deflected.

Intensity is a numerical index describing the effects of an earthquake on the surface of the earth, on man, and on structures built by man. The intensities shown in these maps are the highest likely under the most adverse geologic conditions. There will actually be a range of intensities within any small area such as a town or county, with the highest intensity generally occurring at only a few sites. Earthquakes of all three magnitudes represented in these maps occurred during the 1811 - 1812 New Madrid earthquakes. The isoseismal patterns shown here, however, were simulated based on actual patterns of somewhat smaller but damaging earthquakes that occurred in the New Madrid seismic zone in 1843 and 1895.

This map shows the highest projected Modified Mercalli intensities by county from a potential 7.6 magnitude earthquake centered along the New Madrid Fault.