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.
GPS measurements made since 1996 seem to show this earthquake-prone area slowing down. Is it time to relax? Scientists who studied these data in detail say no, and this fact sheet explains why.
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.
Information on earthquakes in central and eastern United States with links to earthquake monitoring, published products, recent earthquake information, discussion group, and current projects.
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.
Shows where earthquakes occur here, the type of damage that has occurred, and the information that USGS provides to help people anticipate and understand this hazard.