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.
The USGS Seismological Laboratory in Albuquerque installs and maintains a world network of seismograph stations, collects the seismic data, and evaluates seismic instruments. Site includes links to ASL publications, earthquake maps and seismic data.
Photographic archive collection from the USGS Photo Library. Photos dated 1868-1992 are of geology, earthquake damage, national parks, pioneer photographers, St. Helens eruption and mining and available at 100, 700 and 1400 dots/inch resolution.
Study of the probability of a major earthquake in San Francisco Bay region with colored map and links to relevant publications. Text also available in PDF format and graphic available in Illustrator or Photoshop format.
Describes the monitoring effort and provides real-time data of the current restless activity of the caldera, including earthquakes, ground deformation, and release of volcanic gas and plus link to volcano monitoring techniques.
Homepage for a paleoseismic field study of the geologic record of prehistoric earthquakes in the Puget Lowland region to evaluate seismic hazards with links to an atlas and reports on historic earthquakes in the Washington and Oregon area.
Online booklet on the San Andreas fault system on the California coastal region with discussion of faults, relationship of faults and earthquakes, magnitude of earthquakes, and earthquake probability.
U.S. Department of the Interior |
U.S. Geological Survey