ash
VOLCANIC ASHFALL
INFORMATION AND SAFETY RULES
Volcanic
eruptions and ashfall is real threat for the Inland Northwest, especially with
the close proximity of Mount St. Helens. On the morning of May 18, 1980, many
people in eastern Washington noticed dark, threatening clouds approaching from
the west. Most thought the clouds were part of one of the enormous thunderstorms
common in late spring. However, what they did not know was that at 8:32 a.m.
Mount St. Helens had erupted explosively, blasting an enormous column of volcanic
ash and gas more than 60,000 feet into the air.
As
the clouds drifted overhead, a rain of ash began to fall, plunging much of the
region into darkness that lasted all day. Homes, farms, and roads were quickly
covered by as much as 4 inches of gritty ash. The smallest ash particles penetrated
machinery and all but the most tightly sealed structures. By the end of the
day, more than 500 million tons of ash had fallen onto parts of Washington,
Idaho, and Montana. The ash prevented travel throughout much of eastern Washington
because of poor visibility, slippery roads, and ash-damaged vehicles, stranding
more than 10,000 people and isolating many small communities. More than $1 billion
in property and economic losses was caused by Mount St. Helens' 1980 eruptionmuch
of it by ash. Future large explosive eruptions in the United States are certain
to produce widespread ash falls and are likely to cause even greater losses.
Since 1980, rapid population and economic growth in the Western United States,
widespread use of computers and electronics, and the dramatic increase in jet-airline
traffic, especially over the North Pacific, have made more people and property
in the Nation vulnerable to the effects of volcanic ash. Knowing the characteristics
of volcanic ash and being prepared when a volcano shows signs of restlessness
can significantly reduce the potential economic and health impacts of airborne
and falling ash.
Mount Saint Helen's ash plume
in 1980.
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Mount Saint Helen's ash plume
in 2004.
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What To Do
If A Volcano Erupts
Volcanic Ashfall - How to be Prepared for an Ashfall
-- How to protect your home, car, children, and pets --
-- Washington
State Military Department, Emergency Management Division, and the USGS
Cascades Volcano Observatory, 1999
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What is Volcanic
Ash ?
Volcanic ash is rock
that has been pulverized into dust or sand by volcanic activity. In very
large eruptions, ash is accompanied by rocks having the weight and density
of hailstones. Volcanic ash is hot near the volcano, but it is cool when
it falls at greater distances. Ashfall blocks sunlight, reducing visibility
and sometimes causing darkness. Ashfall can be accompanied by lightning.
Fresh volcanic ash is gritty, abrasive, sometimes corrosive, and always
unpleasant. Although ash is not highly toxic, it can trouble infants,
the elderly and those with respiratory ailments. Small ash particles can
abrade the front of the eye under windy and ashy conditions.
Ash abrades and jams
machinery. It contaminates and clogs ventilation, water supplies and drains.
Ash also causes electrical short circuits -- in transmission lines (especially
when wet), in computers, and in microelectronic devices. Power often goes
out during and after ashfall. Long-term exposure to wet ash can corrode
metal.
Ash accumulates like
heavy snowfall, but doesn't melt. The weight of ash can cause roofs to
collapse. A one-inch layer of ash weighs 5-10 pounds per square foot when
dry, but 10-15 pounds per square foot when wet. Wet ash is slippery. Ash
resuspended by wind, and human activity can disrupt lives for months after
an eruption.
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What to do
in case of an ashfall
GENERAL
PRINCIPLES
- Know in advance
what to expect and how to deal with it; that will make it manageable.
- In ashy areas,
use dust masks and eye protection. If you don't have a dust mask, use
a wet handkerchief.
- As much as possible,
keep ash out of buildings, machinery, air and water supplies, downspouts,
stormdrains, etc.
- Stay indoors to
minimize exposure -- especially if you have respiratory ailments.
- Minimize travel
-- driving in ash is hazardous to you and your car.
- Don't tie up phone
line with non-emergency calls.
- Use your radio
for information on the ashfall.
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What to do
before an ashfall
Whether in a car, at
home, at work or play, you should always be prepared. Intermittent ashfall
and resuspension of ash on the ground may continue for years.
YOUR HOME
Keep these items in your home in case of any natural hazards emergency:
- Extra dust masks.
- Enough non-perishable
food for at least three days.
- Enough drinking
water for at least three days (one gallon per person per day).
- Plastic wrap (to
keep ash out of electronics).
- First aid kit and
regular medications.
- Battery-operated
radio with extra batteries.
- Lanterns or flashlights
with extra batteries.
- Extra wood, if
you have a fireplace or wood stove.
- Extra blankets
and warm clothing.
- Cleaning supplies
(broom, vacuum, shovels, etc.).
- Small amount of
extra cash (ATM machines may not be working).
YOUR CHILDREN
- Explain what a
volcano is and what they should expect and do if ash falls.
- Know your school's
emergency plan.
- Have quiet games
and activities available.
YOUR PETS
- Store extra food
and drinking water.
- Keep extra medicine
on hand.
- Keep your animals
under cover, if possible.
YOUR CAR
Any vehicle can be considered a movable, second home. Always carry a few
items in your vehicle in case of delays, emergencies, or mechanical failures.
- Dust masks and
eye protection.
- Blankets and extra
clothing.
- Emergency food
and drinking water.
- General emergency
supplies: first aid kit, flashlight, fire extinguisher, took lit, flares,
matches, survival manual, etc.
- Waterproof tarp,
heavy tow rope.
- Extra air and oil
filters, extra oil, windshield wiper blades and windshield washer fluid.
- Cell phone with
extra battery.
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What to do
during and after an ashfall
YOUR HOME
- Close doors, windows
and dampers. Place damp towels at door thresholds and other draft sources;
tape drafty windows.
- Dampen ash in yard
and streets to reduce resuspension.
- Put stoppers in
the tops of your drainpipes (at the gutters).
- Protect dust sensitive
electronics.
- Since most roofs
cannot support more than four inches of wet ash, keep roofs free of
thick accumulation. Once ashfall stops, sweep or shovel ash from roofs
and gutters. Wear your dust mask and use precaution on ladders and roofs.
- Remove outdoor
clothing before entering a building. Brush, shake and pre-soak ashy
clothing before washing.
- If there is ash
in your water, let it settle and then use the clear water. In rare cases
where there is a lot of ash in the water supply, do not use your dishwasher
or washing machine.
- You may eat vegetables
from the garden, but wash them first.
- Dust often using
vacuum attachments rather than dust cloths, which may become abrasive.
- Use battery operated
radio to receive information.
YOUR CHILDREN
- Follow school's
directions for care of children at school.
- Keep children indoors;
discourage active play in dusty settings. Dust masks do not fit well
on small children.
YOUR PETS
- Keep pets indoors.
If pets go out, brush or vacuum them before letting them indoors.
- Make sure livestock
have clean food and water.
- Discourage active
play in dusty settings.
YOUR CAR
- If possible, do
not drive; ash is harmful to vehicles.
- If you must drive,
drive slowly, use headlights, and use ample windshield washer fluid.
- Change oil, oil
filters, and airfilters frequently (every 50 to 100 miles in heavy dust,
i.e., less than 50 feet visibility; every 500 to 1,000 miles in light
dust).
- Do not drive without
an air filter. If you cannot change the air filter, clean it by blowing
air through from the inside out.
- If car stalls or
brakes fail, push car to the side of the road to avoid collisions. Stay
with your car.
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What to do
during the clean up period
- Minimize driving and other
activities that resuspend ash.
- Remove as much ash as you
can from frequently used areas. Clean from the top down. Wear a dust
mask.
- Prior to sweeping, dampen
ash to ease removal. Be careful to not wash ash into drainpipes, sewers,
storm drains, etc.
- Use water sparingly. Widespread
use of water for clean-up may deplete public water supply.
- Maintain protection for
dust-sensitive items (e.g., computers, machinery) until the environment
is really ash-free.
- Seek advice from public
officials regarding disposal of volcanic ash in your community.
- Wet ash can be slippery.
Use caution when climbing on ladders and roofs.
- Establish childcare to assist
parents involved in cleanup.
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For more information call:
Washington
State Emergency Management Division at (800) 562-6108
U.S.
Geological Survey at (360) 993-8900
Or call your local Emergency
Management Office
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