BACKGROUND:
Volcanic eruptions cause earthquakes in three main
ways. First, the ascent of magma inside the Earth beneath a volcano triggers
earthquakes. This upward movement causes the magma chamber to expand. This
puts stress on the rocks around it, causing earthquakes. Second, earthquakes
occur for similar reasons as magma moves upwards through the vent of the
volcano. Finally, the explosions associated with violent eruptions can cause
earthquakes. The patterns that these earthquakes produce are extremely
useful to vulcanologists (scientists who study volcanoes). They use them to
try and predict the timing of an eruption. For example, they can track the
ascent of magma in the volcano by watching patterns in the depth of the
earthquakes.
Earthquakes are one of many tools used to predict
eruptions. Some volcanoes swell or bulge before they erupt, as their magma
chambers and vents fill with new magma. Others release differing quantities
of gases. Finally, scientists also study the history of volcanoes. The past
behavior of a volcano is often a good predictor of what it will do in the
future.
Volcano prediction is an inexact science. Many
unmeasurable variables effect exactly when eruptions take place. The main
goal of scientists is to make their predictions as accurate as possible, so
that governments can order evacuations or take other appropriate measures.
PROCEDURE:
In this exercise, students focus on the patterns of
earthquakes that occur before an eruption
- Explain why earthquakes occur before and during
volcanic eruptions.
- Point out to the students that other things besides
the disruption of people's lives are effected by an eruption. Animal
life, the atmosphere, and plant life are all damaged during volcanic
events.
ANSWERS:
- How can scientists predict that this volcano
may erupt?
Earthquakes will occur as the magma rises and displaces the
surrounding rock.
- Color RED the homes that are effected by the
eruption of the volcano.
Students should color the two homes on the eastern part of the
volcano. However, if the students reason that ash will affect the
two homes on the western portion, that can also be a justified
answer.
- What else might be affected by this eruption?
Wildlife, lakes, nearby homes through earthquakes.
