BACKGROUND:
Many hazards are associated with volcanic eruptions.
This lab focuses on four hazards: lava, gases, ash flows, and
landslides.
When lava (melted rock) erupts, this thick liquid flows downhill. It is very
hot, so it burns or melts almost everything in its path.
Gases such as CO2
(carbon dioxide), CO (carbon monoxide) and SO2 (sulfur dioxide)
are also emitted by volcanoes. These gases can kill most animals. Gases may
be discharged at the summit area during eruptions or along vents on the
sides of the volcano. Heavier gases than air, particularly CO2,
can also flow down the sides of the volcano. They may fill valleys with a
thick blanket of toxic gas, which may kill much of the life in the area.
Large amount of ash frequently shoot high into atmosphere. The heavier
particles settle back to the Earth’s surface, forming a layers of ash.
Depending on the size of the eruption, this layer can be a few inches to
several feet in thickness. The smaller particles are carried away by the
wind. The particles of ash, along they are very small, can cause breathing
problems in animals. The particles can get into their lungs and suffocate
the animal. They may settle further away, or may interfere with flying
aircraft.
Landslides are a downhill movement of loose material on the side
of a volcano. Landslides on volcanoes result when unstable rocks are shaken
loose during eruptions, or when ash mixes with water and snow, making a
thick slurry that flows down the sides of the volcano.
Some volcanoes are explosive and kill people and other
animal life with little warning. Mt. Pinatubo in the Phillippine and Mt. St.
Helens, in western Washington caused many problems because of the ash that
was set off in the atmosphere. Nevado del Ruiz in Columbia, killed thousands
of people because of mudslides that occurred when melted snow and ash
combined, creating wall of mud that came cascading down the mountainside into villages. The mud buried the
people alive. Some volcanoes, however, like Kilauea in Hawaii usually erupt
quietly, spewing out lava flows but giving humans amble warning.
Volcanic eruptions rarely happen without warning. An
increase in earthquake activity (due to magma moving upwards); changes in
the amounts of gases coming out of the volcano; and bulging at the summit of
the volcano are signs that geologists look for. Every volcano is different,
so scientists must carefully look at each mountain before predicting its
activity.
Eruptions have positive effects. One of the gases
emitted by volcanoes is steam, which through time has been one of the
sources of water on the Earth. Ash also enriches the soil, making it for
excellent plant growth. A volcano disaster is usually only a
"disaster" when people are involved.
This coloring, drawing, and handwriting exercise
illustrates that a volcano can cause several types of hazards.
PROCEDURE:
- Discuss with the class the hazards that they will be examining in this
worksheet. You may wish to show them pictures of each hazard, to guide
their drawings. You may wish to mention the positive effects of
eruptions as well. Show the students the volcano damage images in the
Volcano Slideshow found on our website (http://msnucleus.org).
This NOAA website has excellent photographs of recent events.
- Have the students draw and color hazards on the worksheet. Notice
there is space for "practice" so students can draw the symbol
once before they put it on the volcano. Have the students trace the
words on the worksheet, to practice their writing skills.
- You may wish to read Hill of Fire by Thomas P. Lewis, to the
class. This story revolves around the eruption of Paricutin, a real
volcano in Mexico, and a little boy's experiences.
