What If Mount St. Helens Erupts Again?

Tips on How to Prepare for a Volcanic Explosion

Johnston Ridge View of Mount St. Helens - April 2009
••• Johnston Ridge View of Mount St. Helens - April 2009. ©Angela M. Brown 2009

Volcanoes such as Mount St. Helens in Washington state generate a wide variety of phenomena that can alter the earth's surface and atmosphere, endangering people, wildlife, and property. These volcanic dangers include not only an eruption of a mountain and associated lava flows but also ash fall and debris flows. If you are visiting or live near any Pacific Northwest volcanoes, such as Mount Rainier, Mount Hood, or Mount St.

Helens, familiarize yourself with the following information.

How to Prepare for a Volcanic Eruption

  • Always have emergency supplies, food, and water stored.
  • Plan an evacuation route away from rivers and streams that may carry mud or debris flow.
  • Keep a battery-operated radio available at all times.
  • If an eruption is predicted, monitor radio, television, websites, or National Oceanic and Atmospheric Administration (NOAA) Weather Radio for evacuation information.
  • Follow the current advice given by the relevant authorities.

What to Do If a Significant Eruption Occurs

  • Evacuate, if advised to do so.
  • Stay indoors and avoid downwind areas if ashfall is predicted.
  • Do not approach the eruption area.
  • Be aware of stream and river channels when evacuating.
  • Move toward the higher ground if mudflows are approaching.

What to Do If Ash Falls in Your Area

  • Have dust masks available.
  • Close doors, windows, vents, and dampers. Place damp towels at door thresholds and other draft sources.
  • Put stoppers on the tops of your drainpipes.
  • Protect dust-sensitive electronics.
  • Keep roofs free of ash in excess of 4 inches.
  • Remove outdoor clothing before entering a building.
  • Wash vegetables from the garden before eating.
  • If ash is in the water, let it settle before drinking.
  • Use a battery-operated radio to receive information.
  • Keep children and pets indoors.
  • Minimize travel—ash may be harmful to your vehicle.
  • Frequently change oil and air filters in your vehicle.

Risks of Volcanic Ash

Volcanic ash is not poisonous, but even small amounts in the air may cause dangerous respiratory problems for infants, older persons, and those with respiratory conditions such as asthma, emphysema, and other chronic lung and heart diseases. People who take medications for existing lung or heart conditions should make sure they have an adequate supply of medications.

How to Protect Yourself From Volcanic Ash

If ashfall in your area is significant, or you have a heart, lung, or respiratory condition, take precautions to protect your lungs. If volcanic ash is present, do the following:

  • Stay inside, if possible.
  • Keep windows and doors closed.
  • Decrease exposure to ash by wearing an effective single-use (disposable) face mask when outside.
  • Replace disposable furnace filters or clean permanent furnace filters frequently.
  • Wear glasses or eye protection in windy conditions to avoid scratching your eye.

How Volcanic Ash Affects Water

It is unlikely that ash will contaminate your water supply. Studies from eruptions of Mount St. Helens found no significant issues that would affect drinking water.

If you do find ash in your drinking water, use an alternative source of drinking water, such as purchased bottled water. Many people using a lot of water at the same time could cause a strain on your water system.

Volcano Eruption Authorities

These organizations provide more information on how to handle volcanic eruptions.