3: Sample Week A Volcano Hypothesis and Analyses
Last week you did PBL Steps 1-6. This reading provides
sample responses that someone could have made after reading
the Volcano Scenario and applying the ESS and PBL approaches.
In Week 2 you were to read and analyze the Volcano Scenario (PBL
Step 1), which contains an event and situation that tie
together the ESS and the PBL Model approaches of the course.
Step 2 of the PBL Model is to list hypothesis , ideas, or
hunches. You were to focus your hypothesis, ideas, or hunches
around the volcano event you read about in the scenario.
Here is an example hypothesis, idea, or hunch relating to the
Volcano Scenario you worked with in Week 2:
volcano affects the Earth's systems by releasing extreme
heat from Earth's core; changing the shape of the land
(lithosphere), the quality of the air (atmosphere), the form and quality of
the water (hydrosphere); and destroying plants and
animals (biosphere). I do not
believe an eruption of Mt. Rainer would have the same
overall effect as did Mt. Pinatubo since Mt. Rainier is
a composite volcano in the Cascade Range like Mt. St. Helen's;
therefore, its eruption should cause results similar to
the Mt. St. Helen's eruption of 1980 rather than Mt. Pinatubo.
of the PBL Model is to list what is known. You were to list
what is known in the form of an Earth system science analysis.
You were not supposed to do any research at that point. You
were to list what you knew and include reasons from your own
thinking, education, and experience.
are some examples of Earth system science interaction
statements from the
Event to Sphere Interactions
gases, including water vapor, are released into the
atmosphere. We know that water vapor comes from ground
water heated by magma because of the geysers at Yellowstone.
in previous great eruptions, large quantities of dust
and ash would be added to the atmosphere, and the dust
could be carried in the upper winds and spread out in
the upper troposphere. The additional dust added to
the atmosphere could produce more brilliant sunrises
and sunsets as it did after the eruption at Krakatoa
eruption would impact the biosphere by resulting in
death for some animals and providing an opportunity for
others. Death would come in many ways, including from the
initial blast itself, the impact of falling material,
burying/smothering/clogging by ash, burning, toxic gases,
reduction in light, and encroachment of organisms "fleeing"
into already populated areas.
ash can be very rich in some cases and could enrich
the lands around the blasted area as was seen after
the 1980 Mt. St. Helen's eruption.
with Mt. St. Helen's, the heat of the eruption would melt
vast quantities of ice that would flow down existing
stream valleys causing extensive flooding.
hydrosphere is impacted primarily in two ways. The most
obvious is that water bodies receive large amounts of
volcanic ash and debris. The second is that the heat
and wind generated, increases evaporation. Evaporation
in combination with water vapor expelled by the volcano
increases local rainfall.
lithosphere is replenished by a volcanic eruption. A
volcanic eruption is the active rearrangement of part
of the lithosphere. Volcanic material is jettisoned
to the surrounding countryside resulting in the deposition
of volcanic ash and pieces of the mountain itself onto
the surrounding topsoil.
with Pinatubo, large amounts of ash and dust would accumulate
on the land surrounding the volcano.
volcanic eruption is part of the lithosphere. Tectonic
plate interactions are behind the volatile nature of
the lithosphere and the cause of volcanic eruptions.
and during an eruption, seismic activity increases.
Earthquakes are common, often coming in swarms. An earthquake
was thought to cause the landslide that caused the Mt.
St. Helen's eruption of 1980.
to Sphere Interactions
dioxide and sulfur dioxide may lead to acid rain. Increased
acidity can act as a mechanism to ruin plant growth as
well as life in surrounding rivers, streams, and
gases released by the volcano and possibly a local decrease
in oxygen concentration may result in death.
hydrologic cycle would temporarily increase. Heating
of the atmosphere by the eruption would result in increased
evaporation. Eventually water vapor from evaporation
and from the volcano would fall as sulfuric acid rain
due to sulfides expelled during the eruption.
ash and acid rain could cause a change in the pH of
surface water and possibly the groundwater.
will be more erosion because of increased rainfall,
such as the mudslides in California that resulted from
the excessive rain of El Niņo.
could cause the blowing and drifting of ash as it does
with sand or snow.
flows of sediment-laden water could continue to rebury
new plants that start to grow.
depends on water. With the water containing ash, the
remaining animals will have little to drink.
The lithosphere will be impacted as old growth forests
are swept away in the flood waters, exposing fragile
soils that will then rapidly erode.
the limited amount of vegetation remaining after the
blast, potential erosion could take place.
is added to the topsoil and increases fertility. I notice
that many crops are grown on the sides of volcanoes
because of the rich soil.
There will be increased turbidity in streams and lakes
as eroded material is deposited. Erosion deposits changed
the creek near my house to a more pond-like environment.
erosion deposits may change the chemical composition of the
water, just as dumping pollutes the water.
E > H > L > B
As with Mt. St. Helen's, the heat of the eruption would melt
vast quantities of ice. During the pre-eruption of a snowcapped
mountain, a noticeable meltdown of the snow due to the increase
in internal heat occurs. This meltdown will increase the water
flow into small streams, creeks, and rivers. As the snow cover
continues to melt, it eventually will pick up more dirt, mud,
and debris from the runoff. The larger the amount of ice
available to melt, the larger the potential mud flow that wipes
out living things in its path.
E > L > A > H > B
Tephra, or volcanic ash, will be carried downwind and will
fall to produce a deposit that covers a broad area, including
rivers, streams, and oceans. The resulting silt will affect
turbidity and oxygen-carbon dioxide cycles. This in turn will affect
the biosphere and lithosphere as the silt filters through and is
deposited on the ocean bottom.
At this point you
are done reading the individual assignment sample responses. To read the sample questions
and problem statement from the Volcano Scenario's team assignment, click here.
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by Chris Kreger
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