Page 251 - New Medley 5 Semester 2

sliding movement between the plates can be sudden and so intense that it quivers

the ground resulting in earthquake.

Damage Due to Earthquakes
An earthquake shatters the houses, buildings,

bridges and collapses communication systems. is
results in the loss of life and property.

Measuring Earthquakes Damage caused by an earthquake

Earthquakes are measured on the Richter scale developed by Charles Richter in
1935. Earthquakes of magnitude 1 or 2 can hardly be felt but those of 3 or 4 are

felt. e ones that measure 5 or more cause much damage to life and property.

Seismograph

An earthquake generates seismic waves that travel Frame transmits earth’s
vibrations to wire
all around on the earth’s surface. An instrument
that records seismic waves is called seismograph. Wire

A seismograph consists of a rod of a pendulum Frame Rotating Pendulum

suspended from a stand, whose lower end is paper Pen
drum
attached with a pen. As the earth trembles, the

pendulum vibrates and makes the pen move over

the paper wrapped on the drum. e drum also
rolls as the pen moves. is makes a pattern on Horizontal earth

the paper. e pattern so obtained on the paper movements
is called a seismogram. A seismograph

Knowledge Zone
1. The highest recorded magnitude of earthquake on Richter scale is 9.5.
2. The countries like Japan, which are highly prone to earthquakes, keep their communication
systems very strong. Any prediction is immediately announced, so that the people in the
concerned area may be able to move to some safer place.

e study of earthquakes is called seismology. People who study earthquakes

are called seismologists. ey predict earthquakes so that the people likely to

be a ected have time to move to a safer place.

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