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.
Overview of volcano hazards in California with links to monitoring data including earthquakes and deformations, long-term outlook, volcano hazards in the area, USGS response plan, image gallery, monitoring and topical studies, publications and references.
Describes volcano monitoring at Yellowstone National Park including an update of recent volcanic activity, real-time data, and link to volcano monitoring techniques information.
Links to geologic information on western states: Alaska, Arizona, California, Hawaii, Idaho, Nevada and Oregon including information on coastal and marine geology, mineral resources, earthquakes, landslides, earthquake hazards and geologic maps.
Description and uses of the Ocean Bottom Seismometer; a self contained data-acquisition system which free falls to the ocean floor and records seismic data generated by airguns and earthquakes.
U.S. Department of the Interior |
U.S. Geological Survey