Vents in the surface of the Earth through which magma and associated gases erupt; also, the forms or structures, usually conical, that are produced by the erupted material. [Glossary of Geology, 4th ed.]
Homepage for USGS Volcano Hazards Program with feature stories, and links to worldwide volcano updates, volcanic hazards, reducing volcanic risk, USGS international programs, and resources such as educator's page, videos, and online reports.
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.
Visual monitoring of volcanoes by closed-circuit television and video monitoring for a permanent video record of events using slow-scan television which permits continuous surveillance at a distance for remote volcanoes or in times of danger.
Volcano Watch is a weekly newsletter issued by the U.S. Geological Survey's Hawaiian Volcano Observatory on volcanic features on the Big Island, volcanic hazards, and informational topics of Long Valley, Montserrat, or Alaska.
This booklet presents a generalized summary of the nature, workings, publications, and hazards of the common types of volcanoes around the world, along with a brief introduction to the techniques of volcano monitoring and research.