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Results for “Earthquake Information Bulletin (USGS)”
Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.
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Old seismographs still operation in northern California
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Earthquakes: November-December 1983
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Volcanic studies at the David A. Johnson Cascades Volcano Observatory
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Book review: When the snakes awake--Animals and earthquakes prediction
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Book review: Earthquake prediction techniques--Their application in Japan
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Evidence for ancient rifting in the New Madrid Earthquake Zone, Missouri
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Magnitude and intensity: Measures of earthquake size and severity
Earthquakes can be measured in terms of either the amount of energy they release (magnitude) or the degree of ground shaking they cause at a particular locality (intensity). Although magnitude and intensity are basically different measures of an earthquake, they are frequently confused by the public and new reports of earthquakes. Part of the confusion probably arises from the general similarity of scales used express these quantities. The various magnitude scales represent logarithmic expressions of the energy released by an earthquake. Magnitude is calculated from the record made by an earthquake on a calibrated seismograph. There are no upper or lower limits to magnitude, although no measured earthquakes have exceeded magnitude 8.9.