A volcano is a vent through which molten rock, ash, and hot gases escape to the Earth's surface. When pressure from gases within the molten rock becomes too great, an eruption occurs. Eruptions can be quiet or explosive. There may be lava flows, flattened landscapes, poisonous gases, and flying rock and ash. Volcanic eruptions can be accompanied by other natural hazards, including earthquakes, lahars (mudflows), flash floods, rockfalls and landslides, acid rain, fire, and under some conditions, tsunamis.
Washington is home to five major active volcanoes: Mount Rainier, Mount Baker, Mount St. Helens, Mount Adams, and Glacier Peak. The U.S. Geological Survey (USGS) considers all but Mount Adams to be "very high threat" volcanoes, with the potential to cause national-scale disasters.
- Find out if you live or work in a volcano hazard area and learn about your community warning systems, emergency plans, and evacuation routes. Contact your local fire department or emergency management agency for more information.
- Be prepared for hazards that can accompany volcanoes: mudflows and flash floods, landslides and rock falls, earthquakes, ashfall, acid rain, and in some cases, tsunamis.
- Plan two evacuation routes out of your neighborhood and be familiar with your community's pre-established evacuation routes.
- Get goggles and disposable breathing masks for each member of the household in case of ashfall. Add them to your emergency supply kits at home and in all vehicles.
- Stay out of the area defined as a restricted zone by emergency officials. Effects of a volcanic eruption can be experienced many miles from a volcano.
- Monitor local media or NOAA Weather Radio for information and emergency instructions.
- If directed by authorities to evacuate, do so immediately.
- Bring animals and livestock into closed shelters.
- Put machinery inside a garage or barn.
- Keep car or truck engines off.
- Unless otherwise directed by authorities, stay indoors until the ash has settled. Close all windows, doors, vents, and dampers (chimney, furnace, air conditioner, fans, etc.).
- Place damp towels at door thresholds and tape drafty windows.
- Wear glasses instead of contact lenses.
- If you have a respiratory ailment, avoid contact with any amount of ash.
- Cover your mouth and nose. Volcanic ash can irritate your respiratory system.
- Avoid areas downwind from the volcano, river valleys, and low-lying areas.
- Beware of mudflows. Move up slope, especially if you hear a roar of a mudflow. The danger increases near streams and river channels. Mudflows can move faster than you can walk or run. Look upstream before crossing a bridge, and do not cross the bridge if mudflow is approaching.
- If caught in a rock fall, roll into a ball to protect your head.
- Keep skin covered to avoid irritation from contact with ashfall.
- Use a dust mask or hold a damp cloth over your face to help breathing.
- Wear goggles to protect your eyes.
- Wear long-sleeved shirt and pants to protect your skin.
- Clear roofs and rain gutters of ashfall. Ashfall is very heavy and can cause buildings to collapse. Use extreme caution when working on a roof.
- Avoid running vehicle engines. Driving can stir up volcanic ash that can clog engines, damage moving parts, and stall vehicles.
- Avoid driving in heavy ashfall unless absolutely required. If you must drive, keep speed down to 35 MPH or slower. Be prepared to change oil, oil filter, and air filters frequently (every 50 to 100 miles in heavy dust and every 500 to 1,000 miles in light dust).
- As much as possible, keep ash out of buildings, machinery, air and water supplies, downspouts, storm drains, etc.
- Volcano Hazard Information - Ready.gov
- Volcano Preparedness - American Red Cross
- Mount Rainier National Park - National Park Service
- Mount St. Helens National Volcanic Monument - USDA Forest Service
- Mount St. Helens Volcano Cam
- Pacific Northwest Seismograph Network
- Volcanoes - National Oceanic and Atmospheric Administration (NOAA)