URL of this page: https://www.nlm.nih.gov/medlineplus/volcanoes.html



A volcano is a vent in the Earth's crust. Hot rock, steam, poisonous gases, and ash reach the Earth's surface when a volcano erupts. An eruption can also cause earthquakes, mudflows and flash floods, rock falls and landslides, acid rain, fires, and even tsunamis.

Volcanic gas and ash can damage the lungs of small infants, older adults, and people with severe respiratory illnesses. Volcanic ash can affect people hundreds of miles away from the eruption.

Although there are no guarantees of safety during a volcanic eruption, you can take actions to protect yourself. You should have a disaster plan. Being prepared can help reduce fear, anxiety, and losses. If you do experience a disaster, it is normal to feel stressed. You may need help in finding ways to cope.

Federal Emergency Management Agency