Homework help earthquakes

Instruments called seismographs are used to determine how large the earthquake was. The instrument uses a weighted pen and a spring and the vibrations from the earthquake makes the pen draw lines onto some paper.

Earthquakes can do great damage to buildings, bridges, railroads, and other structures. The violent shaking during earthquakes often causes other Earth movements, such as avalanches. Some quakes that happen in or near oceans cause huge, destructive waves called tsunamis to sweep ashore.

The shifting masses send out shock waves that may be powerful enough to alter the surface, thrusting up cliffs and opening great cracks in the ground. Earthquakes, called temblors by scientists, occur almost continuously. Fortunately, most of them can be detected only by sensitive instruments called seismographs. Others are felt as small tremors.

Gregory Bull/AP. The sudden shaking of the ground that occurs when masses of rock change position below Earth’s surface is called an earthquake.