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.
Provides links to explanatory materials for the layperson, including information on concepts behind earthquake maps, the use of probability, what the maps mean, how they are made, and answers to frequently asked questions.
Provides detailed technical information on earthquake hazards in the form of frequently asked questions. Desisigned for the technical audience, including building and safety planners.
Information on earthquakes in central and eastern United States with links to earthquake monitoring, published products, recent earthquake information, discussion group, and current projects.
Home page for Northern California Earthquake Hazards Program with links to earthquake news, real-time earthquake and shaking maps, earthquake probabilities, latest earthquake information, hazards and preparedness, research and special features.
Site for the Southern California Earthquake Hazards Program with links to latest quake information, real-time earthquake maps and shaking maps, general information, hazards and preparedness, research, networks, and earthquakes for kids.
Collects a series of short articles on earthquake science and related topics for students, teachers, and parents originally published as weekly features in The San Francisco Chronicle.
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.