GEOLOGY

EARTH SCIENCE

EARTHQUAKES

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
The time an earthquake occurred can be estimated from the ____
A
L-wave arrival time
B
amplitude
C
surface wave arrival time
D
seismic wave size
Explanation: 

Detailed explanation-1: -(Public domain.) The time, location, and magnitude of an earthquake can be determined from the data recorded by seismometer. Seismometers record the vibrations from earthquakes that travel through the Earth. Each seismometer records the shaking of the ground directly beneath it.

Detailed explanation-2: -As the P and S waves travel out from an earthquake the P waves get progressively farther ahead of the S waves. Therefore, the farther a seismic recording station is from the earthquake epicenter the greater will be the difference in time of arrival between the P and S wave.

Detailed explanation-3: -P waves travel fastest and are the first to arrive from the earthquake. In S or shear waves, rock oscillates perpendicular to the direction of wave propagation. In rock, S waves generally travel about 60% the speed of P waves, and the S wave always arrives after the P wave.

Detailed explanation-4: -Surface waves travel more slowly through Earth material at the planet’s surface and are predominantly lower frequency than body waves. They are easily distinguished on a seismogram. Shallow earthquakes produce stronger surface waves; the strength of the surface waves are reduced in deeper earthquakes.

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