Volcanoes are a surface feature of molten rock below the
surface of the Earth. When pressure builds up, eruptions occur. Gas and
rock shoot up through the opening; lava flows downward along the sides of
the mountain. Eruptions can cause lateral blasts, lava flows, hot ash flows,
mudslides, avalanches, falling ash and floods (if melting
snow). Volcanic eruptions have been
known to knock down entire forests in one large, burst of hot air. An
erupting volcano can trigger tsunamis, flashfloods, earthquakes, mudflows
and rock falls.
Many hazards are associated with volcanic eruptions. When lava (melted rock) erupts, a thick, hot, viscous liquid
flows downhill. It is very hot, so it burns or melts almost everything that
is in its path. Gases, such as CO2 (carbon dioxide), CO (carbon
monoxide) and SO2 (sulfur dioxide) are also emitted by
volcanoes. They may fill valleys with a thick blanket of toxic gas, which
may kill much of the life in the area.
Landslides are 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. Earthquakes
occur as magma moves upward inside the volcano, and as energy is explosively
released during an eruption. The earthquakes associated with volcanoes are
usually relatively small; they generally cause little damage by themselves.
Some volcanoes are explosive and kill people and other
animal life with little warning. Three examples are Mt. Pinatubo in
the Philippines, Mount St. Helens in western Washington, and Nevado del Ruiz
in Columbia. Some volcanoes, however, like Kilauea in Hawaii or Mount Etna in
Italy, usually erupt quietly, spewing out lava flows. But even quiet
ones sometimes explore when least expected, as the animated storybook
- Using the list of volcanic hazards below, ask the
students to predict the effect each hazard would have on a person or a
home. The hazards and some of their destructive capabilities are listed
- HOT LAVA -
temperatures can melt steel, burn wood structures
- VIOLENT ERUPTIONS
- produce ash, which may bury surrounding areas up to many miles
- VIOLENT ERUPTIONS
- produce ash and mudslides, which destroy life and property around
- GASES - can
- EARTHQUAKES -
may trigger landslides
- LANDSLIDES -
bury and destroy homes, carry people away.
- In most cases the students should answer that the
people or homes will be severely damaged or destroyed if they are too
close to the volcano.
- Read Leaving the Fiery Slopes of Mount Etna by J.R. Blueford
and discuss the different hazards that faced the Pagano Family.
Also discuss the long term effects of such natural disastrous and how it
can change the life of people.
(*NOTE--FOR THE HAZARDS- LAB, STUDENTS NEED TO BRING
IN THEIR MODELS OF MT. LASSEN FROM THE VOLCANOES UNIT BACK INTO THE