arthquakes
are the shaking, rolling or sudden shock of the earth’s
surface. Earthquakes happen along
"fault lines" in the
earth’s crust. Earthquakes can be felt over large areas
although they usually last less than one minute. Earthquakes
cannot be predicted -- although scientists are working on
it!
Most of the time, you will notice an earthquake by the
gentle shaking of the ground. You may notice hanging
plants
swaying or objects wobbling on shelves. Sometimes you may
hear a low rumbling noise or feel a sharp jolt. A survivor
of the 1906 earthquake in San Francisco said the sensation
was like riding a bicycle down a long flight of stairs.
he
intensity of an earthquake can be measured. One measurement
is called the Richter scale. Earthquakes below 4.0 on the
Richter scale usually do not cause damage, and earthquakes
below 2.0 usually can’t be felt. Earthquakes over 5.0 on the
scale can cause damage. A magnitude
6.0 earthquake is
considered strong and a magnitude 7.0 is a major earthquake.
The Northridge Earthquake, which hit Southern California in
1994, was magnitude 6.7.
Earthquakes are sometimes called temblors, quakes,
shakers or seismic activity. The most important thing to
remember during an earthquake is to
DROP and COVER. Drop and
cover means to DROP to the floor and get under something for
COVER.
