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This the link to the workshop homepage: 18-20 March 2009
Why Do Earthquakes Happen?
Earthquakes are usually caused when rock underground suddenly breaks along a fault. This sudden release of energy causes the seismic waves that make the ground shake. When two blocks of rock or two plates are rubbing against each other, they stick a little. They don't just slide smoothly; the rocks catch on each other. The rocks are still pushing against each other, but not moving. After a while, the rocks break because of all the pressure that's built up. When the rocks break, the earthquake occurs. During the earthquake and afterward, the plates or blocks of rock start moving, and they continue to move until they get stuck again. The spot underground where the rock breaks is called the focus of the earthquake. The place right above the focus (on top of the ground) is called the epicenter of the earthquake.
Earthquake-like seismic waves can also be caused by explosions underground. These explosions may be set off to break rock while making tunnels for roads, railroads, subways, or mines. These explosions, however, don't cause very strong seismic waves. You may not even feel them. Sometimes seismic waves occur when the roof or walls of a mine collapse. These can sometimes be felt by people near the mine. The largest underground explosions, from tests of nuclear warheads (bombs), can create seismic waves very much like large earthquakes. This fact has been exploited as a means to enforce the global nuclear test ban, because no nuclear warhead can be detonated on earth without producing such seismic waves.
|Types of Waves||Description|
|P Waves||The fastest kind of seismic waves|
|S Waves||Second wave you feel in an earth-quake|
|Love Waves||The fastest surface wave|
|Rayleigh Waves||Moves the ground surface up and down|
What Should I Do Before, During, And After An Earthquake?
What to Do Before an Earthquake
- Make sure you have a fire extinguisher, first aid kit, a battery-powered radio, a flashlight, and extra batteries at home.
- Learn first aid.
- Learn how to turn off the gas, water, and electricity.
- Make up a plan of where to meet your family after an earthquake.
- Don't leave heavy objects on shelves (they'll fall during a quake).
- Anchor heavy furniture, cupboards, and appliances to the walls or floor.
- Learn the earthquake plan at your school or workplace
What to Do During an Earthquake
- Stay calm! If you're indoors, stay inside. If you're outside, stay outside.
- If you're indoors, stand against a wall near the center of the building, stand in a doorway, or crawl under heavy furniture (a desk or table). Stay away from windows and outside doors.
- If you're outdoors, stay in the open away from power lines or anything that might fall. Stay away from buildings (stuff might fall off the building or the building could fall on you).
- Don't use matches, candles, or any flame. Broken gas lines and fire don't mix.
- If you're in a car, stop the car and stay inside the car until the earthquake stops.
- Don't use elevators (they'll probably get stuck anyway).
What to Do After an Earthquake
- Check yourself and others for injuries. Provide first aid for anyone who needs it.
- Check water, gas, and electric lines for damage. If any are damaged, shut off the valves. *Check for the smell of gas. If you smell it, open all the windows and doors, leave immediately, and report it to the authorities (use someone else's phone).
- Turn on the radio. Don't use the phone unless it's an emergency.
- Stay out of damaged buildings.
- Be careful around broken glass and debris. Wear boots or sturdy shoes to keep from cutting your feet.
- Be careful of chimneys (they may fall on you).
- Stay away from beaches. Tsunamis and seiches sometimes hit after the ground has stopped shaking.
- Stay away from damaged areas.
- If you're at school or work, follow the emergency plan or the instructions of the person in charge.
- Expect aftershocks.
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--Itsmemaipelo 06:59, 19 March 2009 (UTC)