Ground shaking caused by the sudden release of accumulated strain by an abrupt shift of rock along a fracture in the earth or by volcanic or magmatic activity, or other sudden stress changes in the earth.
Fact sheet on hazards from earthquakes and tsunamis in Puerto Rico and the U.S. Virgin Islands to be downloaded as a PDF file or viewed as an Adobe Acrobat Reader file.
Information on earthquakes in central California and the San Francisco region with links to four types of field studies, deep seismic investigations, geotechnical investigations, shallow seismic imaging, and airborne geophysical surveys.
Description and photos documenting offsets and 260 km rupture in the Denali glacier in central Alaska after the November 3, 2002 earthquake, the 9th largest earthquake in the United States in the last 200 years.
Description of the seismic monitoring of the active Hawaiian volcanoes with information on the network, instrumentation, and recording stations with links to related information.
Real-time earthquake maps of the conterminous U.S., Alaska, Hawaii, and Puerto Rico displaying magnitude and location of earthquake activity in the past hour, past day, and past week.
Near-real-time maps of location, ground motion, and shaking intensity of earthquakes in California and Nevada for the past hour, past day, and past week and links to other earthquake information.
Information on world earthquake activity with links to facts and lists on large earthquakes, earthquake e-mail notification, hazards and preparedness, educational links, news and highlights and other seismic information.
U.S. Department of the Interior |
U.S. Geological Survey