Steven R. Brantley Peter R. Stauffer James W. Hendley II Bobbie Myers 1997 <p>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.</p> application/pdf 10.3133/fs00297 en U.S. Geological Survey What are volcano hazards? reports