Fast Facts About Earthquakes
- Earthquakes strike suddenly, violently, and without warning at any
time of the year and at any time of the day or night.
- Smaller earthquakes often follow the main shock.
- An earthquake is caused by the breaking and shifting of rock beneath
the Earth's surface. Ground shaking from earthquakes can collapse buildings
and bridges; disrupt gas, electric, and phone service; and sometimes
trigger landslides, avalanches, flash floods, fires, and huge, destructive
ocean waves (tsunamis).
- Most earthquake-related injuries result from collapsing walls, flying
glass, and falling objects.
- In the United States, several thousand shocks of varying sizes occur
annually and 70 to 75 damaging earthquakes occur throughout the world
on an annual basis. All 50 states and all U.S. territories are vulnerable
to earthquakes. Where earthquakes have occurred in the past, they will
happen again.
- California experiences the most frequent damaging earthquakes; however,
Alaska experiences the greatest number of large earthquakes—most
located in uninhabited areas.
- Earthquakes occur most frequently west of the Rocky Mountains, although
historically the most violent earthquakes have occurred in the central
United States.
- The largest earthquakes felt in the United States were along the New
Madrid Fault in Missouri, where a 3-month long series of quakes from
1811 to 1812 included three quakes larger than a magnitude of 8 on the
Richter Scale. These earthquakes were felt over the entire Eastern United
States (over 2 million square miles) with Missouri, Tennessee, Kentucky,
Indiana, Illinois, Ohio, Alabama, Arkansas, and Mississippi experiencing
the strongest ground shaking.
- The Richter Scale, developed by Charles F. Richter in 1935, is a logarithmic
measurement of the amount of energy released by an earthquake. Earthquakes
with a magnitude of at least 4.5 are strong enough to be recorded by
sensitive seismographs all over the world.
- Estimates of losses from a future earthquake in the United States approach $200 billion.
Last Modified: Wednesday, 22-Aug-2007 13:44:52 EDT