measuring earthquakes
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The vibrations produced by earthquakes are detected, recorded, and measured by instruments call seismographs.The zig-zag line made by a seismograph, called a "seismogram," reflects the changing intensity of the vibrations by responding to the motion of the ground
surface beneath the instrument. The two general types of vibrations produced by earthquakes are surface
waves, which travel along the Earth's surface, and body waves, which
travel through the Earth.Body waves are of two types, compressional and shear. Both types
pass through the Earth's interior from the focus of an earthquake to distant
points on the surface, but only compressional waves travel through the Earth's
molten core.
surface beneath the instrument. The two general types of vibrations produced by earthquakes are surface
waves, which travel along the Earth's surface, and body waves, which
travel through the Earth.Body waves are of two types, compressional and shear. Both types
pass through the Earth's interior from the focus of an earthquake to distant
points on the surface, but only compressional waves travel through the Earth's
molten core.