 |
| Earthquake |
| View Poster |
Headlines
- Aid Flows in to Haiti
- Glimmers of Hope Amid Devastation in Haiti
- How Haiti's Earthquake Unfolded
An earthquake is a tremor of the earth's surface usually triggered by the release of underground stress along fault lines. This release causes movement in masses of rock and resulting shock waves. In spite of extensive research and sophisticated equipment, it is impossible to predict an earthquake, although experts can estimate the likelihood of an earthquake occurring in a particular region.
In 1935, American seismologist Charles Richter developed a scale that measures the magnitude of seismic waves. Called the Richter scale, it rates earth tremors on a scale from 1 to 9, with 9 being the most powerful and each number representing an increase of ten times the energy over the previous number. According to this scale, any quake that is higher than 4.5 can cause damage to stone buildings; quakes rated a magnitude of 7 and above are considered very severe. A less-known scale, the Mercalli scale, was devised by Italian seismologist Giuseppe Mercalli to measure the severity of an earthquake in terms of its impact on a particular area and its inhabitants and buildings.Some earthquakes are too small to be felt but can cause movement of the earth, opening up holes and displacing rocks. Shock waves from a very powerful earthquake can trigger smaller quakes hundreds of miles away from the epicenter. Approximately 1,000 earthquakes measuring 5.0 and above occur yearly. Earthquakes of the greatest intensity happen about once a year and major earthquakes (7.0-7.9) occur about 18 times a year. Strong earthquakes (6.0-6.9) occur about 10 times a month and moderate earthquakes (5.0-5.9) happen more than twice daily. Most earthquakes are not even noticed by the general public, since they happen either under the ocean or in unpopulated areas. Sometimes an earthquake under the ocean can be so severe, it will cause a tsunami, responsible for far greater damage.
The greatest danger of an earthquake comes from falling buildings and structures and flying glass, stones and other objects.
If you live in an earthquake-prone area, here are some steps that can be taken to minimize risks:
- Affix bookcases, cabinets, refrigerators and furniture to the walls.
- Fit cabinets with "childproof locks," so doors will remain closed and items won't fly out.
- California and Japan sell silicone putty kits that can be used to stick dishes and other breakables to the walls.
- Have a backpack prepared and attached to the bed, containing shoes, a flashlight and batteries, keys, money, first-aid supplies and medicines, a knife, food, water, ID and insurance information. Attaching the pack to the bed helps to insure that it will not be thrown around during an earthquake.
- Keep shoes next to your bed, so you can put them on as soon as a quake begins.
- Have a family evacuation plan including phone numbers and a safe place to which to evacuate.
- Establish escape routes from each room in the house.
- If you are indoors, find a secure location to wait out the quake, such as under a heavy table or desk, or in an interior hallway where you can brace yourself between two walls. Doorways are among the safest places to stand, thanks to the strong beams overhead. However, watch out for swinging doors. Stay away from windows.
- If you are outdoors, try to get into an open area, away from falling buildings, power lines, trees, etc.
- If you are in a crowded public area, crouch down, with your hands protecting your head and neck.
- If you are in your car, pull over to the side, away from power lines and overpasses, and stay inside the car until the shaking has subsided.
- Be sure to put on shoes immediately, to avoid injury from stepping on broken glass and objects.
- Check yourself and others for injuries.
- Check for gas and water leaks and damage to electrical wires. Only turn off gas lines if there is damage; it may take a while for technicians to get to your area to turn gas and power back on.
- Survey the exterior of your home for structural damage to the chimney, roof, foundation and walls.
- Do NOT use your automobile unless there is an emergency.
- If you must leave the area, try to leave word where you can be contacted.
