• Weekly report of worldwide volcanic activity
• Current updates for volcanoes in the U.S., the Northern Mariana Islands, and Russia

A National Volcano Early Warning System – NVEWS – is being formulated by the Consortium of U.S. Volcano Observatories (CUSVO) to establish a proactive, fully integrated, national-scale monitoring effort that ensures the most threatening volcanoes in the United States are properly monitored in advance of the onset of unrest and at levels commensurate with the threats posed. Volcanic threat is the combination of hazards (the destructive natural phenomena produced by a volcano) and exposure (people and property at risk from the hazards).

According to a new USGS report on NVEWS, since 1980, 45 eruptions and 15 cases of notable volcanic unrest have occurred at 33 U.S. volcanoes. About half of the most threatening U.S. volcanoes are monitored at a basic level and a few are well monitored with a suite of modern instruments. However, the report cautions, monitoring capabilities at many hazardous volcanoes are sparse or antiquated, and some hazardous volcanoes have no ground-based monitoring whatsoever.

Recognizing that there are potentially dangerous volcanoes within the United States and its Territories that have inadequate or no ground-based monitoring, the USGS Volcano Hazards Program, with CUSVO, is preparing a plan for a National Volcano Early Warning System (NVEWS).

Interferogram showing uplift about 3 miles west of South Sister, Oregon; Interferogram by C. Wicks

InSAR is a proven technique for mapping ground deformation using radar images from Earth-orbiting satellites. InSAR stands for Interferometric Synthetic Aperture Radar. Satellites record images of the Earth's surface, and these images can be combined to show subtle movements of the ground surface, called deformation.

InSAR greatly extends the ability of scientists to monitor volcanoes because, unlike other techniques that rely on measurements at a few points, InSAR produces a spatially complete map of ground deformation with centimeter-scale accuracy without subjecting field crews to hazardous conditions on the ground.