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Why Talk About Volcanoes?
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The United States is third in the world, after Japan and
for the number of active volcanoes. Since 1980, as many as
have erupted each year in the United States. Eruptions are most likely
to occur in Hawaii and Alaska. For the Cascade Range in Washington,
and California, volcanoes erupt on the average of one to two each
produce a wide variety of hazards that can kill people and destroy
Large explosive eruptions can endanger people and property hundreds of
miles away and even affect global climate.
What Are Volcanoes, and What Causes Them to Erupt?
A volcano is a vent through which molten rock escapes to
surface. Unlike other mountains, which are pushed up from
are built by surface accumulation of their eruptive products - layers
lava, ashflows, and ash. When pressure from gases within the molten
becomes too great, an eruption occurs. Volcanic hazards include gases,
lava and pyroclastic flows, landslides, earthquakes, and explosive
Eruptions can be relatively quiet, producing
lava flows that creep
across the land at 2 to 10 miles per hour. Explosive
eruptions can shoot
columns of gases and rock fragments tens of miles into the atmosphere,
ash hundreds of miles downwind.
Lava flows are streams of molten rock that either pour
from a vent quietly
or explosively by lava fountains. Because of their intense
flows are also great fire hazards. Lava flows destroy everything in
path, but most move slowly enough that people can move out of the way.
The speed at which lava moves across the ground depends on several
including the type of lava erupted, the steepness of the ground, and
rate of lava production at the vent.
Volcanic eruptions can be accompanied by other natural
earthquakes, mudflows and flash floods, rockfalls and landslides,
fires, and (under special conditions) tsunamis.
Historically, lahars have been one of the deadliest
Lahars are mudflows or debris flows composed mostly of volcanic
on the flanks of a volcano. These flows of mud, rock, and water can
down valley and stream channels at speeds of 20 to 40 miles per hour
can travel more than 50 miles. Some lahars contain so much rock debris
that they look like fast-moving rivers of wet concrete. They can occur
both during an eruption and when a volcano is quiet. The water that
lahars can come from melting snow and ice, intense rainfall, or the
of a summit crater lake. Large lahars are a potential hazard
communities downstream from glacier-clad volcanoes, such as Mount
Volcanic ash is actually fine, glassy rock fragments and
people and equipment hundreds of miles away from the cone of the
ash can contaminate water supplies, cause electrical storms, disrupt
operation of all machinery, and collapse roofs. Volcanic ash poses an
threat to aviation safety as transportation expands throughout the
rim. Airborne ash can diminish visibility, damage flight
and cause jet engines to fail. Many federal agencies,
the Federal Aviation
and the NOAA/National
are working together to issue timely warnings to airports and airline
Volcanoes usually give warning that they will erupt.
scientists have developed a forecasting system to alert public
and the general public to the fact that a volcano may erupt.
Learn about volcano risk in your community.
Contact your local emergency
management office, American
Red Cross chapter, or state geological surveys or departments
resources. Ask about the type of volcano hazards that could affect your
Develop a Family Disaster Plan. Please see the "Family
section for general family
planning information. Develop a volcano-specific plan. Learn
activity in your community. While volcanoes are located in
areas, ash may be carried some distance away during an explosive
Contact your local emergency management agency, American Red Cross
or state geological survey or department of natural resources.
Most eruptions at Hawaiian volcanoes are not
explosive and are characterized
by the relatively quiet outflow of very fluid lava. These eruptions can
still be deadly, because the lava may be erupted in huge volumes, and
steeper slopes, fluid lava can rapidly travel many miles from its
island of Hawaii (the largest of the Hawaiian islands) experiences
of earthquakes associated with active volcanoes each year. Most of
are too small to feel, but about once a decade, a large quake shakes
entire island and causes widespread damage. Before and
during an eruption,
many small earthquakes occur as molten rock forces its way through the
upper parts of a volcano's interior. Such quakes often provide early
of changes in eruptive activity.
In the past few thousand years, the volcanoes of the
which stretches from northern California into British Columbia, have
produced more than 100 eruptions, most of them explosive.
individual Cascades volcanoes can lie dormant for many centuries
eruptions, and the great risk posed by volcanic activity in the region
is therefore not always apparent. When Cascades volcanoes do erupt,
avalanches of hot ash and rock (pyroclastic flows), lava flows, and
can devastate areas 10 or more miles away, and huge mudflows of
ash and debris (lahars) can inundate valleys more than 50 miles
If you are at risk from volcanic activity:
Learn about your community warning systems and emergency
Different communities have different ways of providing warnings and
responses. Discuss volcanic activity. Many communities have sirens
for outdoor warning purposes. Use a NOAA Weather Radio with a
feature to keep you aware of watches and warnings while you are indoors.
Talk to your insurance agent. Find out what your
will or won't cover in the event of a volcanic eruption.
Develop an evacuation plan. (See "Evacuation"
in the "Family Disaster Plan" section.) Everyone in your family should
know where to go if they have to leave. Trying to make plans at the
minute can be upsetting and create confusion.
Discuss volcanoes with your family. Everyone
should know what to
do in case all family members are not together. Discussing volcanic
ahead of time will help reduce fear and anxiety, and lets everyone know
how to respond. Review landslide and mudflow safety and preparedness
with your family.
Assemble a Disaster
Please see the section "Disaster
for general supplies kit information. Volcanic eruption-specific
should include the following:
A pair of goggles and throw-away breathing mask for each
member of the
household in case of ashfall.
Disaster Suplies Kit basics.
Evacuation Supply Kit.
Media and Community Education Ideas
If you live in a volcano risk area, publish a
special section in
your local newspaper with emergency information on volcanoes. Localize
the information by including the phone numbers of local emergency
offices, the American Red Cross chapter, and local hospitals.
Feature an interview with a representative of the U.S.
talking about how this group determines the likelihood of a volcanic
Run a series on local volcanic hazards and how
to recognize the
warning signals of a possible volcanic eruption.
Work with local emergency services and American Red Cross
to prepare special reports for people who are disabled on what to do if
an evacuation is ordered.
Publish emergency evacuation routes.
What to Do During a Volcanic Eruption
Be prepared for the hazards that can accompany volcanic
know how to respond to reduce risk. Hazards include the
Follow the evacuation order issued by authorities and put your
plan into action. Although it may seem safe to stay at home
out an eruption, if you are in a hazardous zone, doing so could be very
dangerous. The advice of local authorities is your best advice for
Mudflows and flash floods. Mudflows are
powerful "rivers" of mud
that can move 20 to 40 miles per hour. Hot ash or lava from a volcanic
eruption can rapidly melt snow and ice at the summit of a volcano. The
melted water quickly mixes with falling ash, with soil cover on lower
and with debris in its path. This turbulent mixture is dangerous in
channels and can travel more than 50 miles away from a volcano. Intense
rainfall can erode fresh volcanic deposits to form large mudflows. If
see the water level of a stream begin to rise, quickly move to high
If a mudflow is approaching or passes a bridge, stay away from the
Landslides and rockfalls.
Ashfall and acid rain.
Avoid areas downwind and river valleys downstream of
Debris and ash will be carried by wind and gravity. Stay in areas where
you will not be further exposed to volcanic eruption hazards.
Stay out of the area defined as a restricted zone by
Effects of a volcanic eruption can be experienced many miles from a
Mudflows and flash flooding, wildland fires, and even deadly hot
can reach you even if you cannot see the volcano during an eruption.
If caught indoors:
Close all windows, doors, and dampers to keep volcanic
ash from entering.
Put all machinery inside a garage or barn to protect it
ash. If buildings are not available, cover machinery with
Bring animals and livestock into closed shelters to
protect them from
breathing volcanic ash.
If trapped outdoors:
Seek shelter indoors. Your safest place is
indoors, away from various
If caught in a rockfall, roll into a ball to protect
your head and neck.
A tight ball will provide the best protection for your body. Your head
and neck are more easily injured than other parts of your body.
If caught near a stream, be aware of mudflows,
especially if you hear
the roar of an approaching mudflow. Mudflows often accompany
eruptions. Move quickly out of the path.
Avoid river valleys and low-lying areas.
Trying to watch an erupting
volcano up close is a deadly idea.
Listen to a portable, battery-operated radio or
television for updated
emergency information and instructions. If the electricity is
this may be your main source of information. Local radio and local
provide the most appropriate advice for your particular situation.
How to Protect Yourself During Ashfall
Volcanic ash is actually fine, glassy fragments
and particles that
can cause severe injury to breathing passages, eyes, and open wounds,
irritation to skin.
Wear long-sleeved shirts and long pants.
Use goggles to protect your eyes.
Wear eyeglasses instead of contact lenses.
Use a dust mask or hold a damp cloth over your face to help breathing.
Keep car or truck engines off.
What to Do After a Volcanic Eruption
Help a neighbor who may require special assistance -
people, and people with disabilities. Elderly people and
disabilities may require additional assistance. People who care for
or who have large families may need additional assistance in emergency
If possible, stay away from volcanic ashfall areas.
The fine, glassy
particles of volcanic ash can increase the health risk to children and
people with existing respiratory conditions such as asthma, chronic
or emphysema. Stay indoors, wear face masks designed to protect against
lung damage from small particles, use eyeglasses instead of contacts,
protective goggles to protect eyes.
When outside, protect yourself from the fine, glassy
particles of volcanic
Cover your mouth and nose.
Wear goggles to protect your eyes.
Wear eyeglasses instead of contact lenses.
Keep skin covered to avoid irritation from contact with ash.
Clear roofs of ashfall. Ashfall is very heavy
and can cause buildings
to collapse, especially if made wet by rainfall. Exercise great caution
when working on a roof.
Avoid driving in heavy ashfall. Driving will
stir up volcanic ash
that can clog engines and stall vehicles. Moving parts can be damaged
abrasion, including bearings, brakes, and transmissions.
If you have a respiratory ailment, avoid contact with any
ash. Stay indoors until local health officials advise it is safe to go
outside. Volcanic ash can cause great damage to breathing
and the respiratory system.
Produced by the National
Disaster Education Coalition:
Red Cross, FEMA,
and USGS. HTML
formating By the
From: Talking About Disaster: Guide for Standard
by the National Disaster Education Coalition, Washington, D.C., 1999.
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