Measuring Earthquake Magnitude
Earthquakes can be felt in different ways. You might notice your chair shifting while sitting still or in a tall building. You could feel the entire structure sway.
Scientists measure earthquakes using a seismograph, which measures seismic waves. Seismographs produce a seismogram, which is a paper record of the waves, but today most modern seismographs are digital.
Seismographs work using a weighted pen attached to a stationary frame. A rotating drum with paper is connected to the ground. When an earthquake occurs, the ground moves, shaking the drum while the pen remains still.
This creates a wavy pattern on the paper called a seismogram which provides details about an earthquake's strength, how long it lasted, and how far away it was. The height of the waves on the seismogram helps determine the magnitude of the earthquake.
The first waves are P waves, which are the fastest. S-waves come next and are usually larger than P-waves. The surface waves arrive just after the S-waves. If the earthquake has a shallow focus, the surface waves are the largest ones recorded.
Earthquakes can be felt in different ways. You might notice your chair shifting while sitting still or in a tall building. You could feel the entire structure sway.
Scientists measure earthquakes using a seismograph, which measures seismic waves. Seismographs produce a seismogram, which is a paper record of the waves, but today most modern seismographs are digital.
Seismographs work using a weighted pen attached to a stationary frame. A rotating drum with paper is connected to the ground. When an earthquake occurs, the ground moves, shaking the drum while the pen remains still.
This creates a wavy pattern on the paper called a seismogram which provides details about an earthquake's strength, how long it lasted, and how far away it was. The height of the waves on the seismogram helps determine the magnitude of the earthquake.
The first waves are P waves, which are the fastest. S-waves come next and are usually larger than P-waves. The surface waves arrive just after the S-waves. If the earthquake has a shallow focus, the surface waves are the largest ones recorded.
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