Volcanoes of the USA - click on lower rightVolcanic Hazard Mapping
Volcanoes are vents, or ruptures, in the Earth's crust that allow molten rock, lava, gases, ash, and other eruptive materials to escape. Eruptions can pose numerous hazards such as lava flows, pyroclastic flows, lahars, direct volcanic blasts, volcanic bombs, ashfall, and more. Volcanic activity is often associated with earthquakes as the magma moves upward through the earth, fracturing the surrounding rock. In addition, volcanic activity often triggers other types of natural hazards, including flooding, landslides, avalanches, wildfires, tsunamis, and weather.
Maps of volcanic hazards help plan for and prevent losses due to volcanic eruptions. Small-scale regional maps show active or potentially active volcanoes and depict populations at risk from an eruption. More detailed local volcanic hazard maps outline areas likely to be affected by the actual blast or lava flows, model likely areas and depths of ashfall deposition due to different eruption and weather patterns, and depict areas likely to be affected by lahars or by flooding or mudflows as result of glacier or snow melt.
The United States Geologic Survey, or USGS, is the primary federal agency in the US responsible for monitoring, mapping, and forecasting volcanic hazards. The USGS manages regional volcano observatories that monitor local conditions and issue warnings and alerts. FEMA and other federal, state, or local agencies may be involved as well. Some resources are listed at left.
See anything we missed? Your suggestions help us improve this website. Questions, comments, suggestions? Contact Us
Mount Saint Helens, Washington, 1980.
Photo A. Post, Courtesy USGS
USGS Natural Hazards: Volcanoes - General information and a map of volcanic observatories.
USGS Volcanic Hazards program - Interactive map of volcanic hazard warning in the US and more.
USGS Volcanic Hazards Assessments - Technical reports of volcanic hazards (often including maps) for volcanoes in the US and the Pacific Rim.
USGS Natural Hazards Support System - Interactive map viewer with layers for recent earthquake, volcanic activity, tsunami activity, and much more.
USGS Alaska Volcano Observatory - Monitors volcanic activity and studies hazards for volcanoes in Alaska.
USGS Cascades Volcano Observatory - Monitors volcanic activity and studies hazards for volcanoes in the Cascades
USGS Hawaii Volcano Observatory - Monitors volcanic activity and studies hazards for volcanoes in Hawaii.
USGS Yellowstone Volcano Observatory - Monitors volcanic activity and studies hazards for volcanoes in Yellowstone NP.
USGS Long Valley Volcano Observatory - Monitors volcanic activity and studies hazards for volcanoes in Long Valley, CA.
FEMA Volcanic Hazard Page- General information on earthquake hazard, disasters and hazard preparedness.
For state-specific information, contact your State Geologist and your State Office of Emergency Management. At a local level, contact your city or county emergency management, planning, zoning, environmental and/or health department.
American Red Cross - Natural disaster preparedness and relief.