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 Alaska Volcano Observatory (AVO) with offices in Anchorage and Fairbanks monitors and studies Alaska's hazardous volcanoes. Links to featured news, updates, publications and products, and a volcano atlas for Alaska.
An explanation of toxic carbon dioxide emissions at Mammoth Mountain in Long Valley caldera, and a description of magmatic helium discharge at the Mammoth Mountain fumarole with photos, maps, and links to other studies.
Portal to information provided by the Cascades Volcano Observatory in Vancouver, WA with links to reports and activity in the Cascade Range and other volcanoes and multiple links to general information on volcanology, reports, research, and maps.
Article in the May 28, 1998 issue of Volcano Watch describing of correlation of earth tides to volcanic eruptions and value in monitoring underground magma movement with deformation measurement instruments including tiltmeters and strainmeters.
Of 129 reported incidents, 94 are confirmed ash encounters, 79 of which entailed airframe or engine damage; 20 are low-severity events involving suspected ash or gas clouds; for 15 the data are insufficient to assess severity.