To survive a volcanic eruption, you act early on official warnings and you know which hazard your location faces. We define an eruption emergency as the hours when falling ash, toxic gas, flying rock, lava and the mudflows called lahars can all arrive at once. The goal is simple: your family ends the day indoors, unhurt and accounted for.
You may live within reach of a Cascade peak, an Alaska volcano or Hawaii's Kilauea. You may also be visiting one on vacation. Once an eruption is under way, the prepping is done and the acting begins. The right move depends on where you stand: at home, in the car or out on a trail. Each place has its own hazards, and each one has a clear answer.
Start by finding the volcano closest to you and the hazards that reach your address. Your county hazard map shows whether you sit in an ashfall zone, a lahar path or both. Then sign up for local emergency alerts on your phone this weekend. The warning will reach you the minute it is issued.
The First Minutes: How to Survive a Volcanic Eruption Starts With the Warning
Acting on the first warning gets you on the road while it is still open, or behind closed doors before the ash arrives. You get the channels that carry eruption alerts, the meaning of each USGS level and one clear rule for each kind of order. Once the order is clear, the next job is sealing your home against ash.
Where the Alert Comes From
Keep at least two of these channels working, so one dead battery does not leave you guessing.
- Local officials. Your county emergency management office and sheriff issue evacuation and shelter orders for your address. Their order is the one you act on.
- USGS volcano alert levels. The U.S. Geological Survey volcano observatories rate each monitored volcano as Normal, Advisory, Watch or Warning. Check your volcano's current level online so you know the starting point.
- Wireless Emergency Alerts. These arrive on your phone with a loud tone, and no app is needed. Confirm they are switched on in your phone settings today.
- NOAA Weather Radio. The National Weather Service broadcasts ashfall advisories and warnings day and night. A battery or hand-crank model keeps talking when cell towers go quiet.
Read the Levels Like a Ladder
Normal means the volcano is in its typical, non-eruptive state. Advisory means signs of unrest are above background. Watch means unrest is growing, or a minor eruption is under way with limited hazards. Warning means a hazardous eruption is imminent, under way or suspected.
Match your actions to each step. At Advisory, review your family plan and top off your supplies. At Watch, fuel the car, charge every phone and stage your go-bags by the door. At Warning, listen for your local order and act on it the moment it comes.
Evacuate or Shelter: One Rule Each
When told to evacuate, go at once by the route given. Officials choose routes that stay out of the valleys where lahars run. A shortcut you know well may sit right in one, so the assigned route is the safer drive even when it is longer.
When told to shelter, get inside and seal up. A shelter order means the air outside is the main danger, and staying put protects you better than driving through it.
Waiting to see what happens feels reasonable, and most volcanic unrest does end without a large eruption. Once an order comes, though, the waiting has done its job. People who survive a volcanic eruption most often moved early, while roads were clear and shelters had room. Your preparedness work pays off here, and the supplies and routes to set up ahead of time are laid out in How to Prepare for a Volcanic Eruption.
Shelter Indoors: Keep the Grit Outside
Ash can travel hundreds of miles on the wind, so sheltering well is how most families survive a volcanic eruption without ever seeing the mountain. You get a room by room routine and a clear rule for the roof. If the eruption finds you away from home, the car and trail steps come right after.
Seal the Envelope
Close every window and outside door first. Then close the fireplace damper. Turn off the furnace, air conditioner, whole-house fan and every kitchen and bathroom exhaust fan. Each of these pulls outside air, and the ash in it, into your living space. A closed house gets stuffy, so run a small fan indoors to move air and gather in the coolest room.
Volcanic ash is powdered rock and volcanic glass. It scratches, irritates and drifts through the smallest gaps. Lay damp towels along the bottom of doors and on windowsills to trap it. Rewet them as they dry, since a dry towel catches very little. Choose one door as the only entry and set a bin beside it for shoes and outer layers. That small mudroom keeps the rest of the house clean.
Room by Room
- Living room. Cover TVs, computers and routers with plastic sheeting or trash bags. Ash is abrasive and conducts electricity when wet, so unplug anything you are not using.
- Kitchen. Cover open food and keep stored water tightly capped. If you have time before the ash arrives, fill extra jugs so you have clean water if the supply gets contaminated.
- Bedrooms. Set out an N95 respirator for every person, with smaller sizes for children. Masks work best when they fit, so have everyone try one on while things are calm.
- Pets. Bring pets inside before the ash starts and keep them there. Wipe paws and fur with a damp cloth, since pets lick off whatever they carry in.
If you rent an apartment, you have fewer windows to seal and a building manager who handles the roof. If you own a house, you have more openings to close and full control over how you close them. The apartment buttons up faster, and the house lets you build the mudroom your way. For mask fit and the health effects of ash, see Volcanic Ash: Protecting Your Lungs, Home and Water.
Roof Collapse Under Wet Ash
Ash piles up like snow but weighs far more, and wet ash can weigh about twice as much as dry ash. When Mount Pinatubo erupted in the Philippines in 1991, a typhoon soaked the falling ash, and many deaths came from roofs that collapsed under it. Flat roofs, low-slope roofs, carports and wide garage spans carry the highest risk.
Clear the roof after the ashfall stops and before rain arrives. Work with a partner on the ground, wear a mask and goggles, and tie off a safety harness to a solid anchor. Ash on a roof is slick underfoot, so move slowly and keep your weight low. Bag the ash instead of sweeping it into gutters and drains, where it hardens and blocks the flow. If your roof is steep or you have no harness, clear the edges from a ladder with a long-handled push broom and hire out the rest.
Caught Out: In the Car or on the Trail
Getting to high ground and under cover protects you from the hazards that move fastest. You get rules for driving in ash, a plan for escaping lahars and steps for falling rock and gas. After that comes the step that makes every other one easier: keeping your family together.
Driving Through Ash
Slow down and turn on your headlights the moment ash starts to fall. Falling ash cuts visibility like heavy fog, and ash on the pavement is slick, especially once it gets wet. Leave a long gap behind the car ahead, and set the vents to recirculate to keep ash out of the cabin.
If you cannot see the road, pull completely off it, away from traffic. Turn on your hazard lights and stay inside with the windows up. Wait until you can see clearly before you move again.
The 1997 film Dante's Peak shows this drive in a small Cascade town, as families crawl out under falling ash with their headlights barely cutting the gray. It also shows roads jammed with cars when everyone leaves at the last minute, which is why an early start keeps your route open.
Ash is hard on engines. It clogs the air filter quickly, and fine ash that slips past acts like sandpaper on moving parts. An engine starved of air can stall in the middle of the road. Keep a spare air filter in the trunk if you live downwind of a volcano, and change your oil and filters early once you are clear. Spray plenty of washer fluid before every wipe, because dry wipers drag ash across the glass and scratch it.
Lahars: Mud on the Move
A lahar is a fast-moving flow of volcanic mud, rock and water that pours down river valleys from a volcano. Lahars can travel many miles from the peak and bury everything in the channel, including roads and bridges.
On May 18, 1980, Mount St. Helens erupted in Washington State, killing 57 people and burying hundreds of square miles under ash and debris. Lahars from that eruption raced down the Toutle River valley and destroyed homes and bridges along the way.
A valley road feels like the quick way out, and on most days it is. During an eruption, the valley floor is where the lahar goes. Most people who survive a volcanic eruption outdoors do it by leaving low ground early. Climb out of valleys and away from river channels. If you hear a roar like a freight train, or see a stream suddenly rise and turn muddy, move uphill at a right angle to the channel. Cross bridges only on routes officials have cleared.
Falling Rock and Volcanic Gas
Near the vent, a volcano can throw rocks from pebble size to boulder size. Get inside a sturdy building if one is close. In the open, protect your head with a helmet, a backpack or your arms, and keep moving away from the vent.
The 1997 film Volcano shows this hazard in downtown Los Angeles, where glowing lava bombs rain onto city streets and set cars and buildings on fire. People in the film survive by getting under solid cover and away from the vent, the same moves that protect you near a real eruption.
Volcanic gases such as carbon dioxide are heavier than air and collect in hollows, basements and ditches. An N95 mask blocks ash but not gas, so distance and higher, open ground are your protection. Around Kilauea in Hawaii, the downwind hazard is often vog, a haze of volcanic gas that irritates eyes and lungs.
Lava usually moves slowly enough to walk away from, and it destroys whatever lies in its path. Watch lava and crater activity only from official viewing areas, and follow rangers out when they close a site.
Stay Together and Accounted For
Knowing where everyone is lets you make one plan instead of five. You get a check-in method that works on crowded networks, a meeting place and a way to help neighbors who need it. Then comes the last call: staying put until it is safe.
Check In by Text
Send a text instead of calling. Texts need very little network capacity and keep retrying until they go through, while calls drop when towers are jammed. Write one short message that says where you are, who is with you and what you will do next. Name an out-of-area relative as the family contact, since long-distance lines often clear sooner than local ones.
After you send it, save your battery. Lower the screen brightness, turn on power saving mode and keep the phone in a pocket away from the ash.
Your Meeting Place
If you get separated, go to the meeting place your family picked ahead of time, outside the hazard zone. Choose one spot near home and a second one farther away in case the first is closed. Preppers who live near a volcano often write both on a card in every go-bag, so no one has to remember under stress.
If your children are at school, follow the school's release plan. Schools in hazard zones run their own evacuations and send students to set reunion sites. Meet your children there, which keeps you out of the zone and on open roads.
Neighbors Who Need a Hand
Older neighbors and people with disabilities may miss a phone alert or have no way to drive out. Knock on their door, offer a ride and help them seal a room if they are sheltering. Ask whether anyone uses home oxygen or a powered medical device, and help them reach a shelter with power. A larger household has more people to look after, and it also has more hands to tape windows and make these checks.
Stay Put Until Officials Say It Is Safe
An eruption can pause and then restart, and rain on fresh ash can send new lahars down the valleys. Stay where you are until local officials announce it is safe to return or move. That patience is how families survive a volcanic eruption from the first alert to the all clear. The full routine for leaving together is in Volcano Evacuation Plan for Families, and cleanup and recovery steps are in What to Do After a Volcanic Eruption.
