OPPapers.com

Earthquakes

EARTHQUAKE REFERENCE FILES Earthquake, shaking of the earth's surface caused by
rapid movement of the earth's rocky outer layer. Earthquakes occur when energy stored within
the earth, usually in the form of strain in rocks, suddenly releases. This energy is transmitted to
the surface of the earth by earthquake waves. The study of earthquakes and the waves they create
is called seismology. Scientists who study earthquakes are called seismologists. (Webster's
p.423) The destruction an earthquake causes, depends on its magnitude or the amount of shaking
that occurs. The size varies from small imperceptible shaking, to large shocks felt miles around.
Earthquakes can tear up the ground, make buildings and other structures collapse, and create
tsunamis (large sea waves). Many Lives can be lost because of this destruction. (The Road to
Jaramillo p.211) Several hundred earthquakes, or seismic tremors, occur per day around the
world. A worldwide network of seismographs detect about one million small earthquakes per
year. Very large earthquakes, such as the 1964 Alaskan earthquake, which measured 8.6 on the
Richter scale and caused millions of dollars in damage, occur worldwide once every few years.
Moderate earthquakes, such as the 1989 tremor in Loma Prieta, California (magnitude 7.0), and
the 1995 tremor in Kôbe, Japan (magnitude 6.8), occur about 20 times a year. Moderate
earthquakes also cause millions of dollars in damage and can harm many people. (The Road to
Jaramillo p.213-215) In the last 500 years, several million people have been killed by
earthquakes around the world, including over 240,000 in the 1976 T'ang-Shan, China,
earthquake. Worldwide, earthquakes have also caused severe property and structural damage.
Good precautions, such as education, emergency planning, and constructing stronger, more
flexible structures, can limit the loss of life and decrease the damage caused by earthquakes. (The
Road to Jaramillo p.213-215,263) AN...