your community’s risk from hazards created by volcanic eruptions.
you may be located far from a volcano, the ash from an explosive eruption could
affect your area. Contact your local emergency management office, local American
Red Cross chapter, or state geological survey or department of natural
resources. Ask about the type of volcano hazards that could affect your area and
what you can do to prepare.
Why talk about
produce a wide variety of hazards that can kill people and destroy
Volcanic eruptions fall into two broad types: (1) explosive and
(2) quiet. Hazards from large explosive eruptions include widespread ashfall
(fine glass particles), pyroclastic flows (mixtures of hot gases and pumice
blocks), and massive lahars (volcanic mud or debris flows) that can endanger
people and property nearby as well as tens to hundreds of miles away. Eruptions
can even affect global climate. Hazards from quiet lava flows include igniting
fires and producing chlorine-rich gas clouds where lava pours into the sea.
Since 1980, as many as five volcanoes have erupted each year in the United
States. Eruptions are most likely to occur in Hawaii and Alaska. In the Cascade
Mountain Range in Washington, Oregon, and northern California, volcanoes erupt
on the average of one to two or more each century.
Volcanic ash can
affect people and equipment hundreds of miles from the volcano. Inhaling
volcanic ash can cause serious respiratory problems for people with heart and
Explosive eruption columns pose a serious hazard to
commercial aviation. The ash column can grow rapidly and reach more than 12
miles (19 kilometers) above a volcano in less than 30 minutes, forming an ash
cloud. During the past 14 years, about 80 commercial jets have been damaged by
inadvertently flying into ash clouds, and several have nearly crashed because of
engine failure. Many federal agencies, including the U.S. Geological Survey, the
Federal Aviation Administration, and the National Weather Service, are working
together to issue timely warnings of airborne ash to airports and airline
volcanoes, and what causes them to erupt?
volcano is a vent through which molten rock escapes to the earth’s surface.
Unlike other mountains, which are pushed up from below, volcanoes are built by
surface accumulation of their eruptive products—layers of lava flows, ash flows,
and ash. When pressure from gases within the molten rock becomes too great,
gases drive the molten rock to the surface and an eruption
can volcanoes cause?
the past few thousand years, the volcanoes of the Cascade Mountain Range, which
stretches from northern California into British Columbia, have produced more
than 100 eruptions, most of them explosive. However, individual Cascade Range
volcanoes can lie dormant for many centuries between eruptions, and the great
risk posed by volcanic activity in the region is therefore not always apparent.
When Cascade Range volcanoes do erupt, high-speed avalanches of hot ash and rock
(pyroclastic flows), lava flows, and landslides can devastate areas 10 miles (16
kilometers) or more away, and huge mudflows of volcanic mud and debris (lahars)
can inundate stream valleys at speeds of 20 to 40 miles (32 to 64 kilometers)
per hour and travel more than 50 miles (80 kilometers) downstream.
eruptions at Hawaiian volcanoes are not explosive and are characterized by the
relatively quiet outflow of very fluid lava. These quiet eruptions can produce
spectacular lava fountains or lava flows that creep across the land at the
relatively slow speed of 10 miles (16 kilometers) per hour or so. The speed at
which lava moves across the ground depends on several factors, including the
type of lava erupted, the steepness of the ground, and the rate of lava
production at the vent. Because the temperature of the lava can be
lava flows destroy everything in their path, often causing dangerous fires.
While most lava moves slowly enough that people can get out of the way, wildland
fires can advance rapidly. 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 warnings of changes in eruptive
Volcanic eruptions can be accompanied by other natural hazards:
earthquakes, mudflows and flash floods, rockfalls and landslides, wildland
fires, and (given certain conditions) tsunamis.
How can I
protect myself from the ill effects of a volcanic
need to know the volcanic hazards associated with active and potentially active
volcanoes where you live and where you visit. You must determine the varying
degrees of your own risk and take actions to stay safe and protect your
Learning your community’s warning system, developing and
practicing a household evacuation plan, and being prepared to shelter-in-place
should be important parts of your plan.
What is the
best source of information in case of a volcano watch or warning?
radio or television stations are the best sources of information in a volcanic
Volcanoes usually give warning that they will erupt,
and U.S. Geological Survey (USGS) scientists have developed a forecasting system
to alert public officials and the general public of such warnings. The USGS
Volcano Hazards Program, in collaboration with federal, state, and local
government agencies, universities, and the private sector, operates five volcano
observatories to reduce the risk from volcanic activity. The five observatories
are the Alaska Volcano Observatory, the Hawaiian Volcano Observatory, the
Cascades Volcano Observatory, the Long Valley Caldera Observatory, and the
Yellowstone Volcano Observatory.
Be Prepared for a
| CORE ACTION MESSAGES
• Determine your risk.
Prepare household members.
• Keep goggles and dust masks handy.
|For general preparedness, every household should create and practice a Family Disaster Plan and
assemble and maintain a Disaster Supplies Kit. In addition, every household should take volcano-specific precautions and plan for and practice what to do if a volcano erupts.
If you are at risk from volcanic activity, you
• Learn about
your community’s warning systems and emergency plans. Different
communities have different ways of providing warnings and different response
• Keep handy a
pair of goggles and a dust mask for each member of your household in case of
• Develop an
evacuation plan for volcanic eruptions and
make sure all members of your household know and practice it. (See “Evacuation,
Sheltering, and Post-disaster Safety”)
Be sure to include your animals in your evacuation plan. Making plans at the
last minute can be upsetting and wastes precious time.
volcanoes with members of your household. Discussing
volcanic eruptions ahead of time helps to reduce fear and lets everyone know how
landslide and mudflow safety and preparedness measures with members of your
• Talk to you
insurance agent. Find
out what your homeowners’ policy will or will not cover in the event of a
What to Do During
a Volcanic Eruption
CORE ACTION MESSAGE
• Evacuate or take shelter.
• Listen to a
local station on a portable, battery-operated radio or television for updated
emergency information and instructions. If
the electricity is out, this may be your main source of information. Local
officials will give the most appropriate advice for your particular situation on
local media. For general preparedness, every household should create and
practice a Family
Disaster Plan and
assemble and maintain a Disaster
In addition, every household should take volcano-specific precautions and plan
for and practice what to do if a volcano erupts.
• Follow any
evacuation orders issued by authorities, and put your Family Disaster Plan into
it may seem safe to stay at home and wait out an eruption, if you are in a
hazard zone, doing so could be very dangerous. The best way to stay safe is to
take the advice of local authorities.
• If indoors,
close all window, doors, and dampers to
keep volcanic ash from entering.
• Put all
machinery inside a garage or barn to
protect it from volcanic ash. If buildings are not available, cover machinery
with large tarps.
• Bring animals
and livestock into closed shelters to
protect them from breathing volcanic ash.
• If outdoors,
take shelter indoors. Your
safest place is indoors, away from various hazards.
• Stay out of
designated restricted zones. Effects
of a volcanic eruption can be experienced many miles from a
low-lying areas, areas downwind of the volcano, and river valleys downstream of
the volcano. Debris
and ash will be carried by wind and gravity. Stay in areas where you will not be
further exposed to volcanic eruption hazards. Trying to watch an erupting
volcano up close is a deadly idea.
• If you are
caught in an ashfall:
a dust mask designed to protect against lung irritation from small
-Protect your eyes by wearing goggles. Wear eyeglasses, not
-Keep as much of your skin covered as
What to Do After a Volcanic
CORE ACTION MESSAGES
• Stay inside.
your lungs and eyes.
• Stay indoors
and away from volcanic ashfall areas if possible. The
fine, glassy particles of volcanic ash can increase the health risks for
children and people with respiratory conditions, such as asthma, chronic
bronchitis, or emphysema.
• Whether you
are indoors or outdoors:
-Wear a dust mask designed
to protect against lung irritation from small particles
• When it is
safe to go outside:
eyes by wearing goggles. Wear eyeglasses, not contact lenses.
much of your skin covered as possible.
-Clear roofs of ashfall. Ash
is very heavy and can cause buildings to collapse, especially if made wet by
rain. Exercise great caution when working on a roof.
in heavy ashfall. Driving
will stir up volcanic ash that can clog engines and stall vehicles. Abrasion can
damage moving parts, including bearings, brakes, and
• Keep animals
away from ashfall and areas of possible hot spots. Wash
animals’ paws and fur or skin to prevent their ingesting or inhaling ash while
Media and Community
your local newspaper or radio or television station to:
-Do a series on
the dangers of volcanic eruptions, ashfalls, floods, etc.
-Do a story
featuring interviews with local officials about land use management in low-lying
-Highlight the importance of staying informed about local
-Run public service ads about how to protect lives in the
event of a volcanic eruption.
-Feature an interview with a representative
of the U.S. Geological Survey, talking about how this group determines the
likelihood of a volcanic eruption.
-Do a series on local volcanic hazards
and how to recognize the warning signs of a possible volcanic eruption.
-Publicize emergency evacuation routes.
Help the reporters to localize
the information by providing them with the local emergency telephone number for
the fire, police, and emergency medical services departments (usually 9-1-1) and
emergency numbers for the local utilities and hospitals. Also provide the
business telephone numbers for the local emergency management office, local
American Red Cross chapter, and state geological survey or department of natural
with officials of the local fire, police, and emergency medical services
departments; utilities; hospitals; emergency management office; and American Red
Cross chapter to prepare and disseminate guidelines for people with mobility
impairments about what to do if they have to evacuate.
erupt with regularity.
generally experience a period of closely spaced eruptions followed by long
periods of quiet. Most volcanoes show no regularity, and thus on the basis of
past history alone cannot be considered "overdue" or "ready to
are unpredictable, erupting at any time without warning.
usually give warning signs that they are going to erupt weeks to months or more
in advance. Although we cannot predict when a volcano will start to be restless,
once activity begins, scientists can make general forecasts about how soon an
eruption will occur. A more difficult challenge for volcanologists is
forecasting the size of an impending eruption.
flows are the most significant hazards from volcanoes in the United
this is true in Hawaii, the hazards differ at the more than 150 volcanoes in
other parts of the United States. Principal hazards outside Hawaii include: (1)
Volcanic ashfall resulting from explosive-style eruptions. Volcanic ash, the
shattered remnants of volcanic rock, rises into the atmosphere, where it is a
hazard to aircraft and affects large areas downwind when it falls back to earth.
Where it falls in sufficient quantity, it can cause difficulties for vehicles,
machinery, and utilities, and can be injurious to human health. (2) Volcanic
mudflows (lahars) resulting from the sudden melting of snow and ice during
eruptions. Lahars can inundate river valleys tens of miles distant, destroying
bridges, highways, and other types of development, as well as endangering
cause volcanic eruptions.
indicate a geologically active landscape, but they are not the cause of volcanic
eruptions. In rare cases, large tectonic earthquakes have triggered eruptions of
nearby volcanoes that have been poised to erupt anyway. In the case of Mount St.
Helens, a flurry of earthquakes under the volcano suggested potential eruptive