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This project was made possible
through the Institute of Museum and
Library Services National Leadership
Grant for Museum and Library
Collaboration
Effects of Volcanic Eruptions
This activity complements the Mt. St. Helens and the Volcanic Cascades DVD presentation and
general study guide.
GRADE LEVEL
Junior High (with extensions for High Schoolers)
TIME REQUIRED 3 to 5 classroom sessions (based on 50 minute sessions)
ACTIVITY OBJECTIVES
Students will learn:
The effects of a volcanic eruption on a community.
The effects of a volcanic eruption on the Earth’s environment and geological structure.
The different geological features/events of a volcanic eruption.
About the possible warning signs of a volcanic eruption.
MATERIALS
Map of your area (see Procedure no. 2)
Access to research materials of local mountains (see Procedure no. 3)
Notebook paper
Access to computer and printer
Photograph by Don L. Hunter
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Mt. St. Helens, May 18, 1980
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PROCEDURE (NOTE: THESE ARE SUGGESTED STEPS AND CAN BE MODIFIED ACCORDING TO INSTRUCTOR NEEDS AND RESOURCES)
1. Divide the class into groups of 2-8 (depending on class size).
2. Using a map of the area, each group will determine the closest mountain to your community.
(Note: If a possible volcano is not a realistic option for your local community, see the Extensions
section for possible replacement activities.)
3. Research that mountain. Is it extinct, dormant, or active as a volcano? When was the last time it
erupted, if ever? What type of volcano is it? (See terms.) If it erupted in the documented past,
how did it affect the area around it?
4. Groups will document a fictional volcanic eruption of the mountain chosen in # 2 above. Students will write an outline that describes the various effects of a volcanic eruption on their local
community. It is important to take past eruptions into consideration (if applicable).
The outline will explain:
The extent of:
• Lava flow destruction
• Ash fall
• Changes in the climate
• Other volcanic disturbances (earthquakes, mud flows/slides, pyroclastic flows, gases, etc.)
The effects on:
• Human-built structures
• Human health
• Agriculture
• Livestock
• Forests
• Landscape (change in land formations)
5. Groups will act as “volcanic experts” in a mock Town Hall meeting where they will warn the
local community of a pending eruption. They will create and present a report (2-3 pages) to the
community. Taking the outline described above as a guide, the report will include:
a. The effects the eruption will have on the community and the historical precedence (if
any) of the mountain erupting.
b. What should city officials do to ensure the loss of lives and property is minimized?
c. What should individual residents do? Should they:
• Evacuate the community? How far do they need to go to be safe?
• Bring animals indoors? For how long?
• Store food and water?
• Avoid driving? For how long?
• Other?
d. Explain the long-term changes to the environment, and how it will “bounce” back.
e. Additionally, groups should anticipate the types of questions community residents would
ask about the volcano.
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QUESTIONS FOR CLASS DISCUSSION
1. What types of volcanic effects did you focus on? How do they affect a community? How do
they affect the natural environment? How does a volcanic eruption fit into the natural cycle of
environmental changes?
2. Do you think volcanoes or human populations have more impact on the environment? Why does
one have more impact? What are the negative and positive effects by both volcanoes and humans on the environment?
3. What is the most damaging part of a volcanic eruption (lava flow, pyroclastic flow, ash, bombs,
etc.)? Think about damage in terms of lives lost, property damage, or economic disruption
(change of flight paths, etc.). From your analysis of the nearest volcano, what is the most damaging part of an eruption in your area?
4. What types of occupations would be directly affected by a volcanic eruption? What types would
be indirectly affected? Would your job or your parent’s job(s) be affected if the nearest volcano
erupted?
5. Are there other large-scale natural occurrences that affect communities on such large scales?
What are they? What are the differences and similarities among these occurrences and volcanic
eruptions?
ASSESSMENT
Student assessment may be based on the following specific exercises or in combination:
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Student outlines evaluated in terms of conveying the following information:
o The extent of damage and environmental change created by volcanic eruption.
o The effects this damage and change has on various populations (human, animal, plant,
etc.) and on the landscape.
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Group presentations for “mock Town Hall meeting”:
o Was the group able to accurately describe the extent of the effects of volcanic damage on
the community?
o Were the group’s recommendations reasonable and clear for the community?
o Did the group answer the community’s questions in an articulate and accurate manner?
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Completion of final presentation written paper (2 – 3 pages) sufficiently addressing:
1) The effects the eruption will have on the community and the historical precedence of
the mountain erupting.
2) What city officials should do to minimize the damage caused by an eruption.
3) What individual residents should do.
4) General conclusions.
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Participation in class discussion.
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Matching final student knowledge of the topics in relation to your state standards.
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EXTENSIONS
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Watch the DVD presentation, Mt. St. Helens and the Volcanic Cascades by Don L. Hunter, and
have a class discussion around the topics presented.
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Have students research and complete the same activity as previously outlined in the Procedure
section, but instead pick a city (not their own) with a volcano close to it. How did the eruption
affect this city? Did the community do anything to try to avoid a potential disaster? Is a similar
scenario possible in your community?
Examples:
Yakima, WA Mt. St. Helens (1980), ashfall hazard
Outskirts of Hilo, Hawaii downslope from Mauna Loa (1984), lava flow hazard
East of Lassen Volcano, California near Lassen Peak (1914-17), ashfall hazard
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Find out which natural disaster is most likely in your area. Research what the safety plan is if that
disaster threatened your area.
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Have students research how volcanic eruptions assist scientists/archaeologists in learning about
past human populations and their lifestyles.
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Have students graph out a certain effect of volcanic eruptions (such as the distribution of ash
patterns) in the Cascades over the last 10,000 years.
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Have students research and present on specific Federal Government agencies involved with the
monitoring of natural disasters and how the agency is involved directly in the students’ community.
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Have students create a hazard map of their community and use topography, vent locations, and
potential eruptions styles to map out possible effects of a volcanic eruption.
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Photograph by Don L. Hunter
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TERMS
Ash: Fine material (less than 1/10 an inch in diameter)
ejected in an explosive volcanic eruption, which can contain
volcanic glass, crystals, and pulverized rock from the walls
of the volcanic conduit. These particles are transported by
wind from the volcanic vent into the atmosphere where they
can spread for thousands of miles. Volcanic ash is the most
widespread hazard from volcanic eruptions because of the
large areas it can affect.
Volcanic Ash, Mt. St. Helens
o Ashfall (Airfall includes pumice): Ashfall is the ash that falls from the eruption cloud of
a volcano, creating layers of ash on the surface of the Earth.
o Ash Flow: see pyroclastic flow (below).
Lave tube: A hollow tube in a lava flow formed by drainage of lava after the
formation of a solid surface crust.
Fissure: A surface fracture or crack in rocks; fissures can be located on
volcanic slopes or on active lava domes. Some volcanic eruptions originate
along elongated fissures, instead of central vent structures.
Pyroclastic Flow: A hot gas-supported flow of ash, pumice, and rock particles
that collapse out of a volcanic ash column, or “boil-over” from a volcanic vent.
These flows travel downslope at high speeds causing an extreme asphyxiation
and burn danger for individuals in the flow path.
Photograph by Don L. Hunter
Climatic Effects Of Volcanic Eruptions:
o Ozone Effect is the destruction of earth’s ozone by the introduction of such chemicals as volcanic aerosol gas particles (or human made CFCs). These chemicals create
a hole in earth’s ozone layer, which allows harmful ultraviolet rays from the sun to
enter the Earth’s atmosphere. Volcanic effects on ozone depletion are minimal and
short lived due to the fact that the aerosol gas particles will dissipate in two to three
years.
o Greenhouse Effect is caused by the addition of gases (primarily CO2 and water
vapor) to earth’s atmosphere. The effect causes a rise in global temperatures; CO2
molecules allow short wavelength solar radiation to enter the atmosphere, but absorb
long wavelength infrared radiation from the earth’s surface, thereby trapping heat
energy that creates a cycle where more radiation is allowed into the atmosphere than
is released. Volcanic eruptions add to global warming by adding CO2 to the atmosphere. Scientists have determined that the amount of global warming caused by
eruption-generated greenhouse gases is small.
o Haze Effect is caused by airborne particles from volcanic eruptions that block out
enough sunlight to cause a reduction in global temperatures.
Splintered Tree, Mt. St. Helens,
May 18, 1980 Eruption
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Volcanic Gases: At depth, various species of gases are dissolved in magma. As this magma rises,
these species exsolve (escape) from the magma (form gas bubbles). Some of these gases are toxic
and very harmful and others not as harmful. Examples in general order of abundance include:
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Water Vapor (H20),
Carbon Dioxide (C02)
Sulfur Dioxide (S02)
Hydrogen Sulfide (H2S)
Hydrogen (H2)
Carbon Monoxide (CO)
Hydrogen Chloride (HCL)
Hydrogen Fluoride (HF)
Helium (He)
Carbon dioxide, sulfur dioxide, and hydrogen fluoride are the gases that pose the largest hazards
to humans, animals, and the environment. The main effects include:
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Carbon Dioxide (C02) - In large concentrations, C02 is lethal to humans, animals, and
plants. Breathing in air containing more than 30% C02 can be deadly to humans and
animals, and C02 concentrations in soil above 20% can be toxic to plants and trees.
Sulfur Dioxide (S02) - S02 causes acid rain and downwind air pollution, and can
contribute to ozone and haze effects globally.
Hydrogen Fluoride (HF) - HF molecules can attach to ash particles, which can settle
on plants. The acidic toxin can kill animals who eat the ash coated plants.
Volcanism: The process in which magma from beneath earth’s surface is brought to the surface. In
the Cascades, volcanism is a result of a release of fluids from the subducted Juan de Fuca plate
beneath the North American plate; these fluids lower the melting temperature of rocks deep in the
North America plate, which then “pushes” the magma upwards to the surface.
Three Main Volcano Types:
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Composite Volcanoes or Stratovolcanoes have been built up over thousands of years
and are composed of alternating layers of lava flows, volcanic ash, and fragments of
explosively generated volcanic material, which can rise over 8,000 feet above their
base. Many famous volcanoes/mountains, such as Mount St. Helens, Mount Hood,
Mount Shasta (Cascades, North America), and Mount Fuji (Japan), are stratovolcanoes.
Shield volcanoes are built almost entirely out of fluid lava flows. Such lava flows
accumulations can form large domes tens of thousands of feet from base to summit.
The Hawaiian Islands are made up of shield volcanoes.
Cinder and Scoria Cones are built from accumulated explosive volcanic fragments
(cinders), which pile up around a volcanic vent. These types of volcanoes do not
normally rise more than several hundred feet above the surface, and can be part of a
larger composite cone or stratovolcano. Scientists have identified around 100 cinder
cones on the sides of Mauna Kea shield volcano in Hawaii.
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