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Most earthquakes associated with young volcanoes are related to volcanic processes and may indicate that a quiet volcano is becoming active.
Although large eruptions are often preceded by several significant earthquakes and many small rock breaking quakes, there also is a continuous release of seismic energy associated with the underground movement of magma. Volcanic tremor is a seismic vibration caused by the pulsing of pressurized magma and gas. The seismogram is of longer duration and more continuous than rock-breaking earthquakes of the same amplitude.
Earthquake swarms recorded by seismometers and the ground deformation monitored by tiltmeters help scientists determine the depth and location of flowing magma beneath the volcano, which in turn, gives scientists information to issue hazard warnings.
Title: Volcanic Monitoring Animations #3: Earthquakes
Earthquakes serve as an early warning sign for volcanic eruptions, as well as a marker for the location of moving magma. This animation shows magma movement beneath a volcano, simulated seismograms, volcanic tremor and seismicity associated with an impending eruption.
Location: Vancouver, WA, USA
Date Taken: 1/1/2012
Video Producer: Jenda Johnson , U.S. Geological Survey-Cascades Volcano Observatory
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Additional Video Credits:
This animation was created for the Mount St. Helens Visitor Center in cooperation with the U.S. Geological Survey and the U.S. Forest Service.
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