A volcano is a vent through which molten
rock escapes to the earth’s surface.
When pressure from gases within the molten
rock becomes too great, an eruption occurs.
Eruptions can be quiet or explosive.
There may be lava flows, flattened landscapes,
poisonous gases, and flying rock and
Because of their intense heat, lava flows
are great fire hazards. Lava flows destroy
everything in their path, but most move
slowly enough that people can move out
of the way.
Fresh volcanic ash, made of pulverized
rock, can be abrasive, acidic, gritty,
gassy, and odorous. While not immediately
dangerous to most adults, the acidic gas
and ash can cause lung damage to small
infants, to older adults, and to those
suffering from severe respiratory illnesses.
Volcanic ash also can damage machinery,
including engines and electrical equipment.
Ash accumulations mixed with water become
heavy and can collapse roofs.
Volcanic eruptions can be accompanied by
other natural hazards, including earthquakes,
mudflows and fl ash floods, rock falls
and landslides, acid rain, fire, and (under
special conditions) tsunamis. Active volcanoes
in the U.S. are found mainly in Hawaii,
Alaska, and the Pacific Northwest.
Before a Volcanic Eruption
- Add a pair of goggles and a
disposable breathing mask for each member
of the family to your disaster supplies
- Stay away from active volcano sites.
During a Volcanic Eruption
The following are guidelines for what to
do if a volcano erupts in your area:
- Evacuate immediately from the
volcano area to avoid flying debris,
hot gases, lateral blast, and lava flow.
- Be aware of mudflows. The danger from
a mudflow increases near stream channels
and with prolonged heavy rains. Mudflows
can move faster than you can walk or
run. Look upstream before crossing a bridge, and
do not cross the bridge if mudflow
- Avoid river valleys and low-lying
- Wear long-sleeved shirts and long
- Use goggles and wear eyeglasses instead
of contact lenses.
- Use a dust mask or hold a damp cloth
over your face to help with breathing.
- Stay away from areas downwind from
the volcano to avoid volcanic ash.
- Stay indoors until the ash has settled
unless there is danger of the roof
- Close doors, windows, and all ventilation
in the house (chimney vents, furnaces,
air conditioners, fans, and other vents).
- Clear heavy ash from fl at or low-pitched
roofs and rain gutters.
- Avoid running car or truck engines.
Driving can stir up volcanic ash that
can clog engines, damage moving parts, and stall
- Avoid driving in heavy ash fall unless
absolutely required. If you have to
drive, keep speed down to 35 MPH or slower.
If you require more information about any
of these topics, the following are
resources that may be helpful.
Publications National Weather Service
Heat Wave: A Major
Summer Killer. A website describing the heat index,
disorders, and heat wave safety tips.
Available online at: NOAA - Heat Wave: A Major Summer Killer
Hazards Program. Website with volcano activity
updates, feature stories, information about
volcano hazards, and resources. Available
online at: USGS - Valcano Hazards Program