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.
Answers to a wide variety of questions (FAQs) about earthquakes, such as dictionary of terms, earthquake activity and probabilities, common myths, faults, plate tectonics, and earthquake measurement techniques.
Provides detailed technical information on earthquake hazards in the form of frequently asked questions. Designed for the technical audience, including building and safety planners.
After the powerful earthquake of April 18, 1906, staff of the U.S. Geological Survey stationed in Sacramento and Berkeley brought help to the residents of devastated San Francisco, documented the effects of the quake, and investigated its causes.
Online database of faults and associated folds in the United States that are believed to be sources of significant earthquakes during the last 1.6 million years.