Why is it important to monitor volcanoes?

There are 161 potentially active volcanoes in the United States. According to a 2018 USGS assessment, 57 volcanoes are a high threat or very high threat to public safety. Many of these volcanoes have erupted in the recent past and will erupt again in the foreseeable future. As populations increase, areas near volcanoes are being developed and aviation routes are increasing. As a result, more people and property are at risk from volcanic activity.

Volcanic eruptions are one of Earth's most dramatic and violent agents of change. Not only can powerful explosive eruptions drastically alter land and water for tens of kilometers around a volcano, but tiny liquid droplets of sulfuric acid erupted into the stratosphere can change our planet's climate temporarily. Eruptions often force people living near volcanoes to abandon their land and homes, sometimes forever. Farther away, cities, crops, industrial plants, transportation systems, airplanes, and electrical grids can still be damaged by tephra, ash, lahars, and flooding.

Fortunately, volcanoes exhibit precursory unrest that, when detected and analyzed in time, allows eruptions to be anticipated and communities at risk to be forewarned. The warning time preceding volcanic events typically allows sufficient time for affected communities to implement response plans and mitigation measures.

Learn more: Comprehensive monitoring provides timely warnings of volcano reawakening

Related Content

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January 1, 1998

Volcano hazards from Mount Rainier, Washington, revised 1998

Mount Rainier—at 4393 meters (14,410 feet) the highest peak in the Cascade Range—is a dormant volcano whose load of glacier ice exceeds that of any other mountain in the conterminous United States. This tremendous mass of rock and ice, in combination with great topographic relief, poses a variety of geologic hazards, both during inevitable future eruptions and during the intervening periods of rep

Authors

R. P. Hoblitt, J. S. Wilder, C. L. Driedger, K. M. Scott, P. T. Pringle, J. W. Vallance

October 1, 1997

What are volcano hazards?

Volcanoes give rise to numerous geologic and hydrologic hazards. U.S. Geological Survey (USGS) scientists are assessing hazards at many of the almost 70 active and potentially active volcanoes in the United States. They are closely monitoring activity at the most dangerous of these volcanoes and are prepared to issue warnings of impending eruptions or other hazardous events.

Authors

Bobbie Myers, Steven R. Brantley, Peter R. Stauffer, James W. Hendley

Volcano Hazards Program, Volcano Science Center, Cascades Volcano Observatory

September 1, 1997

Volcano hazards in the Mount Hood region, Oregon

Mount Hood is a potentially active volcano close to rapidly growing communities and recreation areas. The most likely widespread and hazardous consequence of a future eruption will be for lahars (rapidly moving mudflows) to sweep down the entire length of the Sandy (including the Zigzag) and White River valleys. Lahars can be generated by hot volcanic flows that melt snow and ice or by landslides

Authors

W. E. Scott, T. C. Pierson, S. P. Schilling, J. E. Costa, C. A. Gardner, J. W. Vallance, J. J. Major

Volcano Hazards Program, Volcano Science Center, California Volcano Observatory

January 1, 1989

Potential hazards from future volcanic eruptions in California

More than 500 volcanic vents have been identified in the State of California. At least 76 of these vents have erupted, some repeatedly, during the last 10,000 years. Past volcanic activity has ranged in scale and type from small rhyolitic and basaltic eruptions through large catastrophic rhyolitic eruptions. Sooner or later, volcanoes in California will erupt again, and they could have serious imp

Authors

C. Dan Miller