🌋 Volcanic eruption: alerts, ash and lahars
Chile has more than 90 active volcanoes monitored by SERNAGEOMIN. Villarrica, Llaima and Calbuco have emptied entire towns within hours. If you live or holiday near one: what each alert colour means, what to do at each level, and why the danger is almost never the lava.
Key The alert traffic light, level by level
- Green — normal activity. This is when you do the boring work: find out whether your house sits in a lahar zone, get your kit together, and agree where the family meets if there's no phone signal.
- Yellow — activity above baseline. More earthquakes, gas or glow than usual. Check the SERNAGEOMIN report daily, keep documents and medication in a packed bag, and don't camp on or climb the volcano.
- Orange — eruption likely within days or weeks. This is where the decisions that save you get made: fuel tank full, animals sorted, go-bag by the door, and elderly relatives moved out early rather than mid-crisis.
- Red — eruption underway or imminent. You evacuate. This is not the moment to load the car or go back for something: take the marked route, and leave now. A jam on the escape road turns an evacuation into a tragedy.
- These are two separate systems. SERNAGEOMIN describes the technical state of the volcano; SENAPRED declares the public alert and sets the exclusion zones. If SENAPRED orders you out, you go.
Key The lahar: the hazard that kills the most
- What it is. When heat melts snow or ice at the summit, the water picks up ash, mud, rocks and tree trunks and races down the channels. It's a slurry as thick as wet concrete, able to shift huge boulders.
- It travels far and fast. It can run tens of kilometres down the valley and reach places where no ash ever fell. That's why towns outside the exclusion radius can still be at risk: the hazard travels down the river, not in a straight line.
- How to tell if you live in a lahar path. Look for flat, low ground beside a river that starts on the volcano, with rounded stones or loose boulders in the soil. Your municipality's hazard maps will confirm it.
- The escape rule. Never run downhill along the valley — you will not outrun it. Move perpendicular to the channel and climb the nearest slope. And don't cross bridges: they are the first thing to go.
Before If you live near a volcano
- Know your volcano's alert level at sernageomin.cl/alertas-volcanicas, which publishes per-volcano reports, and bookmark it alongside the SENAPRED site.
- Add the volcanic extras to your kit: an N95 mask per person, sealed goggles without side vents, plastic sheeting and tape to seal windows, and a spare air filter. Kit checklist →
- Agree on an evacuation route and meeting point, and drive it once in daylight so you know where the signs are. Keep an out-of-region contact — local phone lines jam first.
- Protect your water supply beforehand. An uncovered tank is ruined by a single night of ashfall. Get a firm lid, be ready to disconnect the rainwater downpipe, and keep three days of bottled water per person.
During Eruption or Red alert
- Evacuate immediately if authorities order it. Whatever exclusion radius they set (typically 10–20 km depending on the volcano) is not negotiable, and it can be widened if activity changes. Shut off gas and power before leaving.
- Stay away from rivers, streams, flats and bridges: that's where lahars come down, even hours or days after the eruptive pulse, and often at night. If you hear a growing low rumble from the channel, don't look — climb.
- During ashfall, stay indoors. Seal doors and windows with damp cloths or tape, switch off extractor fans and air conditioning, cover stored water and cover electronics: the fine dust gets in through any gap.
- If you must go out: N95 mask, sealed goggles, long sleeves and long trousers. Ash is ground glass: it irritates eyes and throat and makes asthma worse. Children, older adults and anyone with heart problems stay inside.
- Avoid driving in ashfall: visibility drops to a few metres, the road turns slippery and the air filter clogs until the engine chokes. If there's no alternative, go very slowly with low beams and don't tailgate.
After Living with the ash
- Clear the roof as soon as it's safe, and before it rains: wet ash weighs roughly twice as much and can collapse light roofing or greenhouses. Work in pairs, use support on slopes, and never do it alone.
- Dampen it lightly before sweeping so it doesn't become airborne again, and take it out in bags to the disposal point your municipality designates. Never wash it down the drain: it sets hard and blocks the pipes.
- Don't use water from canals, wells or uncovered tanks until the health authority clears it. Let it settle, filter it and boil it if there's no alternative, and stick to bottled water for drinking.
- Keep wearing a mask and goggles throughout the clean-up: sweeping raises more dust than the fall itself did. Keep children and anyone with asthma indoors until the streets are clear.
- Check the car before using it again: change the air filter, blow out the radiator and brakes, and rinse the bodywork with plenty of water without dry-wiping, since ash scratches both paint and glass.
Rural Pets and livestock
- Decide at Orange alert, not at Red. Moving animals takes hours and trucks, and during an evacuation the roads close. Get livestock off river flats and channels onto high pasture early.
- If you can't move the herd in time, keep it in a shed with covered feed and water, or turn it loose with the gates open towards high ground. Penned in a low paddock beside a channel it has no chance.
- Watch out for ash-covered pasture. Ash can carry fluoride and other compounds that sicken grazing animals, and it wears their teeth down. Feed stored forage and clean water, and check with your vet before putting animals back out.
Frequently asked questions
What do the volcanic alert colours mean?
SERNAGEOMIN uses a technical traffic-light scale: Green (normal activity), Yellow (activity above baseline), Orange (eruption likely within days or weeks) and Red (eruption underway or imminent). SENAPRED declares the public alert and defines the exclusion and evacuation zones.
What is a lahar and why is it so dangerous?
It's a flow of mud, water, rocks and tree trunks that races down the volcano's channels, even without a major eruption, when heat melts snow or ice near the crater. It can travel tens of kilometres. Never stay in channels, river flats or on bridges during a crisis.
How do I protect myself from volcanic ash?
Stay indoors with doors and windows sealed, switch off forced ventilation, wear an N95 mask and sealed goggles when you go out, cover water tanks and troughs, and clear the roof once ash builds up: wet ash weighs roughly twice as much and can collapse the structure.
Can I drive during ashfall?
Avoid it: ash cuts visibility to a few metres, makes the road slippery and gets into the engine. If it's unavoidable, drive very slowly with low beams, never run the wipers dry because that scratches the glass, and change the air filter afterwards.
Is volcanic ash toxic?
It isn't a poison, but it does harm you: ash is finely ground rock and glass that irritates the eyes and airways and worsens asthma and heart conditions. It can also carry fluoride on its surface, which does affect livestock grazing on ash-covered grass.
Can I drink rainwater or tank water with ash in it?
Not while ash is visible in it, and not until the health authority confirms it's safe. Ash leaves water turbid and acidic and clogs filters and pumps. Cover tanks before the fall, disconnect the rainwater downpipe, and if you must use that water, let it settle, filter it and boil it.
What do I do with my animals if I have to evacuate?
Decide beforehand, not in the moment. Pets leave with you, with their carrier, water and medication. Livestock should be moved off river flats and channels to high pasture early; if you can't manage it, turn them loose with the gates open towards high ground. Never go back for them once the zone is closed.