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Prepping for a volcanic eruption (Part 5): Surviving the ashfall

By The SHTF App Team

The household that rode out the week of ashfall did it from a living room that stayed clean, under a roof they swept twice a day, drinking bottled water they had stored for exactly this. Their neighbors went out to watch the gray sky and came back with silicosis risks, scratched corneas, and a car with a dead engine. By day four, the difference between the two households was visible from the street: one had sealed windows, damp-toweled door gaps, and a pile of ash swept off the roof before breakfast. The other had gray dust on every horizontal surface and a family coughing.

If you can’t evacuate, you shelter in place and ride out the ashfall. Sealing your home, protecting your lungs, and managing the weight of ash on your roof are the skills that keep you alive.

Caution: The “It’ll blow over” assumption. People assume ashfall is brief and harmless. But ash can fall for days or weeks, collapse roofs, and contaminate water. Sheltering in place is a serious, multi-day operation. This is Part 5 of the volcano series.

Disclaimer: The information provided in this article is for general informational and educational purposes only. It is not intended as, and should not be considered, medical or geological advice. Always follow the instructions of local authorities and volcano observatories.

The Readiness Audit

Could you shelter in place through a multi-day ashfall?

  • Green: You have respirators, sealed goggles, several days of food and water, and a plan to seal your home and clear your roof.
  • Yellow: You have some supplies, but no respirators and no plan to manage roof ash.
  • Red: You’d go outside to watch the ash fall.

If you are Yellow or Red, execute Phase 1 immediately.

Phase 1: Sealing the Home

Goal: Keep ash out of your living space.

  • The windows and doors: close and lock all windows and doors. Block gaps with damp towels.
  • The ventilation: turn off HVAC systems, fans, and anything that draws in outside air. Ash is fine enough to seep through small gaps and clog filters.
  • The fireplace: do not use fireplaces or wood stoves, they draw in outside air and ash.

The Takeaway: Your home is your shelter. Seal it against the ash.

Phase 2: Protecting the Lungs

Goal: Breathe safely indoors and out.

  • Indoors: if ash is seeping in, wear an N95 respirator indoors as well.
  • Outdoors: if you must go out, wear an N95 respirator and sealed goggles, and minimize your time outside.
  • The rule: never go outside during ashfall without a respirator. Your lungs are the first casualty.

The Takeaway: A respirator is your most important piece of ashfall equipment. Wear it.

Phase 3: Managing the Roof

Goal: Prevent roof collapse from ash weight.

  • The weight: ash is heavier than snow, and 4 inches of wet ash can collapse a roof.
  • The action: clear ash from the roof before it accumulates dangerously, working from the top down.
  • The safety: wear a respirator and goggles, and work carefully, a weakened roof is a fall hazard.
  • The caution: do not use water, wet ash is heavier and clogs drains.

The Takeaway: Your roof is a ticking clock. Clear the ash before it collapses.

Phase 4: Water and Food

Goal: Survive the duration of the ashfall.

  • The water: ash contaminates water supplies. Drink only bottled or properly filtered water, and cover open containers.
  • The food: stock several days of non-perishable food. Ash can fall for days or weeks.
  • The rule: assume tap water is contaminated until authorities say otherwise.

The Takeaway: Ashfall is a multi-day event. Stock enough food and water to last.

The Essential Kit Checklist

  • The respirators: N95 or better for every family member.
  • The goggles: sealed goggles for every family member.
  • The water: several days of bottled water per person.
  • The food: several days of non-perishable food.
  • The shovel: for clearing ash from the roof.
  • The towels: damp towels to seal door and window gaps.

Scenario Planner (Contingencies)

“The ash is seeping into my house.” The trap: ignoring the fine dust. The fix: seal gaps with damp towels, turn off ventilation, and wear a respirator indoors. Ash is fine enough to seep through small gaps, so seal aggressively.

“My roof is creaking under the ash.” The trap: waiting to see if it holds. The fix: clear the ash now. Four inches of wet ash can collapse a roof. Work from the top down, wear protection, and don’t use water.

Next Steps

  1. Buy the respirators and goggles today. One set per family member plus spares, because ash does not respect the “we’ll get masks later” plan.
  2. Stock the bottled water for the ash duration, several days per person, and cover every open container in the house.
  3. Read the Volcanic Eruption Survival Manual Checklist next, the one-page working document that compresses all five parts into a printable protocol.

Originally adapted from public USGS ashfall guidance (public domain).