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.
History of the Hawaiian Volcano Observatory (HVO), established in 1912, including an overview of Hawaiian volcanic processes and USGS monitoring techniques.
Online booklet giving an introduction to the concept of plate tectonics and complements the information on the map This Dynamic Planet published in 1994 by the U.S. Geological Survey (USGS) and the Smithsonian Institution.
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.
Field Office involved in operating GPS stations, data recording, and supplying of earthquake data. Links to GPS data analysis, photos, and technical information.
Evansville, Indiana, is near the Wabash Valley and New Madrid seismic zones and has experienced minor damage from earthquakes in the past 200 years. This fact sheet describes three types of USGS earthquake hazard maps for Evansville and surrounding areas.
National Strong-Motion Program home page with links to program news, recent events, and datasets of digitized accelerograms downloadable as PC (*.zip) and Unix (*.tar.z) files, data processing, stations, research, publications, and personnel.
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.