A volcano is an opening in the Earth's crust that allows molten rock, gases and debris to escape to the surface. During a volcanic eruption, lava and other debris can flow at speeds of up to 100 mph, destroying everything in their path. Volcanic ash can travel hundreds of miles and cause severe health problems.
There are 161 potentially active volcanoes in the United States. Alaska, Hawaii, California, Washington and Oregon have the largest number of active volcanoes, but other states and territories also have active volcanoes.
A volcanic eruption can:
- Contaminate water supplies.
- Damage machinery.
- Reduce visibility through smog and harmful gases that may threaten low-lying areas.
- Make it hard to breathe and irritate the skin, eyes, nose and throat.
Volcanoes can produce ash, toxic gases, flashfloods of hot water and debris called lahars, lava flows, and fast-moving flows of hot gases and debris called pyroclastic flows. Some dangers from volcanoes can be predicted ahead of time while others may occur with little or no notice after an eruption. Each volcano and situation is unique. Learn more about volcanic eruptions and pay attention to warnings from local authorities for the best advice available on specific actions you can take to stay safe.
