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.
Description of intensity and magnitude as indicators of the size of an earthquake and the levels of severity measured on the Richter Magnitude Scale and the Modified Mercalli Intensity Scale.
Fact sheet describing plans for a San Andreas Fault Observatory at Depth (SAFOD) by drilling into the fault to install instruments for long-term monitoring near the location of the magnitude 6 Parkfield earthquakes.
Annotated list of resources about the great earthquake of 1906, which caused significant devastation in and around San Francisco, California, compiled for the 100th anniversary of the disaster.
Homepage for tsunami research with links to information and images on basics, tsunamis in the Pacific Northwest, the 1998 Papua New Guinea tsunami, research on specific tsunamis, and animations in various formats.
News and related information about the importance of seven major types of natural hazards in the United States: earthquakes, floods, wildfires, hurricanes, landslides, volcanoes, and tsunamis.
Overview of the Pacific Northwest Urban Corridor Geologic Mapping Program concerned with geology and urban hazards with links to online geologic maps, current research, publications, and contacts.
Overview of the Long Valley Caldera 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.
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.
U.S. Department of the Interior |
U.S. Geological Survey