Surviving a volcanic eruption comes down to three things: leaving early if you can, sheltering properly if you can’t, and protecting your lungs from ash. Most volcano-related deaths happen to people who stayed too long in hazard zones or underestimated how far the danger reached. Here’s what to do before, during, and after an eruption.
Know the Alert Levels Before an Eruption
The USGS uses a four-tier alert system for U.S. volcanoes. “Normal” means background activity. “Advisory” means the volcano is showing signs of unrest above its baseline. “Watch” means escalating unrest with increased eruption potential, or an eruption already underway that poses limited hazards. “Warning” means a hazardous eruption is imminent or actively happening.
You can subscribe to the USGS Volcano Notification Service for real-time updates on any monitored volcano. If you live near an active volcano, know your local evacuation routes and hazard zone maps before you ever need them. Local authorities and the USGS develop scenario-based hazard maps during unrest that show which areas are most likely to be hit by lava flows, ashfall, or mudflows based on wind direction and terrain.
Evacuate Early if You Can
The single most important survival decision is to leave before conditions deteriorate. If authorities issue an evacuation order, go immediately. Roads become dangerous fast once ash starts falling, visibility drops to near zero, and vehicles can lose engine power. The people who survive eruptions overwhelmingly are the ones who left when told to.
Avoid areas downwind of the volcano, where ash and debris travel on air currents. Stay away from river valleys and stream channels that drain the volcano, especially if the peak has snow or glacial ice. When hot volcanic material melts that ice, it creates lahars: fast-moving mudflows that follow river valleys and can travel dozens of miles from the summit. If you’re near a stream and notice water rising or turning muddy, move uphill immediately.
What to Do if You Can’t Evacuate
If evacuation isn’t possible and you have adequate supplies, shelter in place. Get indoors and stay there until authorities confirm it’s safe. Seal your home by covering all ventilation openings, including vents, chimneys, and fan ducts, with plastic sheeting and tape. Close and seal doors and windows. Turn off air conditioning and heating systems that pull in outside air. These steps keep fine volcanic ash from infiltrating your living space.
Keep enough food, water, and medication on hand to last several days. The USGS recommends volcano-specific additions to your emergency kit: N95 masks, goggles, spare contact lenses or glasses, extra respiratory medication if you have asthma or COPD, and plastic sheeting with tape for sealing your home.
Protect Your Lungs and Eyes
Volcanic ash isn’t soft like wood ash. It’s made of tiny, jagged fragments of rock and glass that can shred lung tissue, irritate airways, and scratch your eyes. If you must go outside during ashfall, respiratory protection is essential.
The best option is a well-fitting N95 mask (also labeled P2, FFP2, or DS2 depending on the country). A standard pleated surgical mask also filters ash effectively as long as it fits snugly against your face. Simple rectangular healthcare masks, fashion masks, and cloth bandanas are significantly less effective because they don’t filter fine particles well and can’t form a proper seal.
To get a proper seal, fit the mask over your nose and mouth, position the top strap above your ears around the crown of your head and the lower strap below your ears. Gently press the nose clip across your nose and onto your cheeks below the eyes without pinching it. Then cover the mask with both hands and breathe out sharply. If you feel air escaping around the edges, readjust. Facial hair breaks the seal and reduces effectiveness. You can improve the fit by tying a layer of cloth over the mask, though this makes breathing less comfortable.
Wear goggles to protect your eyes, and make sure the goggle frames don’t interfere with the mask’s face seal.
The Deadliest Hazards to Avoid
Not all volcanic hazards are equal. Pyroclastic flows, superheated clouds of gas, rock, and ash that race downhill at hundreds of miles per hour, are essentially unsurvivable if you’re in their path. There is no outrunning them. Your only option is to not be there. If you see or hear a pyroclastic flow approaching, get out of the area by any means available, moving perpendicular to its path if possible.
Volcanic gases are an invisible threat. Eruptions release carbon dioxide, sulfur dioxide, hydrogen sulfide, and other toxic gases. At high concentrations, these cause eye and airway irritation, dizziness, headaches, vomiting, difficulty breathing, and visual disturbances. Carbon dioxide and hydrogen sulfide can pool in low-lying areas like valleys, basements, and depressions, and at high enough concentrations can cause unconsciousness within minutes and death. If you smell sulfur (a rotten-egg odor) or feel sudden dizziness or difficulty breathing, move to higher ground and into fresh air immediately. Longer-term exposure to volcanic gases and ash has been linked to bronchitis, lung infections, and chronic respiratory disease.
Driving Through Ashfall
Avoid driving during heavy ashfall if at all possible. If you absolutely must drive, keep your speed below 35 mph. Ash-covered roads are slippery, and driving kicks ash into the air, destroying visibility for you and everyone nearby. Use headlights on low beam and leave extra following distance.
Do not use your car’s air conditioning or heating system, as it will pull ash-laden air into the cabin. If your car has a recirculate or internal-only air setting, use that and keep the heater blower on high. This slightly pressurizes the cabin and helps keep ash from seeping in through body gaps. Keep windows closed.
Ash destroys engines. It clogs air filters, contaminates oil, scratches windshields, and gums up brake assemblies. Don’t use your wipers on dry ash because it will grind into the glass. Instead, wet the windshield with water and wipe with a cloth. In heavy ash conditions, you may need to change your oil and oil filter every 50 to 100 miles. Don’t drive without an air filter, but don’t replace it until you notice a loss of engine power, because a dirty filter actually catches more fine particles than a clean one.
Cleaning Up After Ashfall
Ash cleanup is when many injuries happen. Wet volcanic ash is extremely heavy, and accumulated ash on a roof can cause structural collapse. Despite this, do not climb onto your roof to remove ash without carefully assessing the risk first. Many injuries and some deaths during eruptions have occurred from falls or roofs giving way during cleanup.
If you decide it’s safe to work on the roof, secure your ladder so it extends at least 3.3 feet above the stepping-off point. On metal roofs, step only along the lines of nails or screws, and don’t cluster workers together in one area. Ash-covered surfaces are extremely slippery, so place boards or ladders on the roof for footing. Stay off steep sections and avoid weak spots like skylights.
A broom works best for sweeping ash off roofs. Lightly dampening the surface reduces the amount of ash that lifts into the air, but don’t soak it. Too much water cements the ash in place and makes it far heavier and harder to remove. When sweeping ash to the ground, keep it away from building entry and exit points. Wear your N95 mask and goggles during all cleanup work.
Prepare Your Kit Now
If you live within range of an active volcano, build your kit before alert levels change. Beyond standard emergency supplies like water, food, flashlights, and a battery-powered radio, add these volcano-specific items:
- N95 masks for every member of your household
- Sealed goggles that fit over or alongside your mask without breaking its seal
- Plastic sheeting and tape for sealing windows, doors, and vents during extreme ashfall
- Spare glasses or contact lenses with cleaning solution, since ash makes contacts unbearable
- Extra respiratory medication if anyone in the household has asthma or a lung condition
Know your evacuation routes, keep your vehicle’s gas tank at least half full, and have a plan for where you’ll go. The window between an advisory and a warning can close fast, and the people who survive are the ones who already had a plan.