The U. S. Geological Survey's Cascades Volcano Observatory Website, which focuses on hazards, activity, history, and monitoring of volcanoes, with emphasis on volcanoes of the Western United States.

A comprehensive overview of the U.S. Geological Survey's Hawaiian Volcano Observatory and the volcanoes of Hawai`i, including Kilauea and Mauna Loa, the most active volcanoes on the Island of Hawai`i, and Hualalai and Mauna Kea.

A comprehensive overview of the U.S. Geological Survey's Volcano Hazards Program and current volcanic activity in the United States. The Volcano Hazards Program monitors volcanoes and collects the best possible scientific information on volcanoes in the United States and elsewhere to reduce the risk from volcanic activity. Site includes ...

A site devoted to the studies being conducted by the U.S. Geological Survey of the Long Valley Caldera in eastern California. Describes the monitoring effort and provides realtime data of the current restless activity of the caldera, including earthquakes, ground deformation, and release of volcanic gas.