An earthquake is a sudden, rapid shaking
of the Earth caused by the breaking and shifting of rock beneath the Earth's
surface. This shaking can cause buildings and bridges to collapse; disrupt
gas, electric, and phone service; and sometimes trigger landslides,
avalanches, flash floods, fires, and huge, destructive ocean waves
(tsunamis). Buildings with foundations resting on unconsolidated landfill,
old waterways, or other unstable soil are most at risk. Buildings or
trailers and manufactured homes not tied to a reinforced foundation anchored
to the ground are also at risk since they can be shaken off their mountings
during an earthquake.
