Earthquake

Terms

Aftershock - An earthquake of similar or lesser intensity that follows the main earthquake.

Earthquake - A sudden slipping or movement of a portion of the earth’s crust, accompanied and followed by a series of vibrations.

Epicenter: The place on the earth’s surface directly above the point on the fault where the earthquake rupture began. Once fault slippage begins, it expands along the fault during the earthquake and can extend hundreds of miles before stopping.

Fault: The fracture across which displacement has occurred during an earthquake. The slippage may range from less than an inch to more than 10 yards in a severe earthquake.

Magnitude: The amount of energy released during an earthquake, which is computed from the amplitude of the seismic waves. A magnitude of 7.0 on the Richter Scale indicates an extremely strong earthquake. Each whole number on the scale represents an increase of about 30 times more energy released than the previous whole number represents. Therefore, an earthquake measuring 6.0 is about 30 times more powerful than one measuring 5.0.

Seismic Waves: Vibrations that travel outward from the earthquake fault at speeds of several miles per second. Although fault slippage directly under a structure can cause considerable damage, the vibrations of seismic waves cause most of the destruction during earthquakes.

Preparing for Earthquakes

  • Repair defective electrical wiring, leaky gas lines, and inflexible utility connections. Get appropriate professional help. Do not work with gas or electrical lines yourself.
  • Bolt down and secure to the wall studs your water heater, refrigerator, furnace, and gas appliances. If recommended by your gas company, have an automatic gas shut-off valve installed that is triggered by strong vibrations.
  • Place large or heavy objects on lower shelves. Fasten shelves, mirrors, and large picture frames to walls. Brace high and top-heavy objects.
  • Store bottled foods, glass, china, and other breakables on low shelves or in cabinets that fasten shut.
  • Anchor overhead lighting fixtures.
  • Be sure the residence is firmly anchored to its foundation.
  • Install flexible pipe fittings to avoid gas or water leaks. Flexible fittings are more resistant to breakage.
  • Locate safe spots in each room under a sturdy table or against an inside wall. Reinforce this information by moving to these places during each drill.
  • Hold earthquake drills with your family members: Drop, cover, and hold on!

During an Earthquake

Minimize your movements during an earthquake to a few steps to a nearby safe place. Stay indoors until the shaking has stopped and you are sure exiting is safe.

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