- How volcanoes erupt
- Types of eruptions
- Magma and lava
- Predicting volcanic eruptions
- Explain how volcanoes erupt.
- Describe and compare the types of volcanic eruptions.
- Distinguish between different types of lava and understand the difference between magma and lava.
- Describe a method for predicting volcanic eruptions.
active volcano: volcano that is currently erupting of showing signs that it will erupt soon
dormant volcano: volcano that is not currently erupting but has erupted in recorded history and may erupt again
eruption: release of lava, tephra, and gases from a volcano
explosive eruption: violent eruption of rock, lava, ash, and large amounts of gas from a volcano
extinct volcano: volcano that has not erupted in recorded history and is unlikely to erupt again
magma chamber: region in the crust below a volcano where magma and gases collect
pyroclast: hot volcanic rock fragments thrown into the air by an explosive volcanic eruption
Introducing the Lesson
Show students brief video segments of explosive and non-explosive volcanic eruptions (see URLs below). Call on students to describe how the two eruptions differ. Tell them they will learn why volcanic eruptions may differ in these ways when they read this lesson.
Assign each of several groups of student a different volcano that has erupted in the last 100 years. Students in each group are to research and report on their volcano. Their reports should include the following information:
- type of volcano
- geographic location
- name, distance, and population of nearest major city
- date of most recent eruption and date of most destructive eruption
- other events associated with the last eruption (earthquakes, floods, mudslides, etc.)
To their report, students should attach a one-page description of the major hazards to humans in the vicinity of this volcano. They should also speculate on what they would do if they were in charge of minimizing the risk to the population. Set aside time for students to report to the class on their volcano. Direct students to the URL below to find resources to start their research.
Suggest that students explore the interactive volcano animation at the URL below. They will see how a tall volcano has been built up by layers of ash and lava from previous eruptions and how and why it erupts again after a period of dormancy.
Have students make a Venn diagram showing the similarities and differences between explosive and non-explosive volcanic eruptions and the type of magma associated with each type of eruption.
Ask one or more interested students to learn about careers in volcanology and report back to the class. The following URL is a good place for them to start.
Use the inquiry activity at the following URL so students can identify factors that cause explosive eruptions. In the activity, you will use an impressive soda eruption as an analogy to help students understand how and why explosive volcanic eruptions occur.
By doing the group activity “Volcano!” described at the following URL, students will act as teams of volcanologists assigned to advise the president of the United States. Each group is to give the president a report on what can be expected to happen, and what steps can be taken to help people cope with, the eruption of a certain volcano. Objectives of the activity are for students to understand that:
- Volcanic eruptions that take place near populated areas can be disastrous.
- The level of destruction caused by a volcanic eruption depends on several factors, including the type of volcanic eruption and the speed at which the lava or ash flows.
- Volcanic eruptions can often be predicted.
- Measures can be taken to help people cope with the disaster of a volcanic eruption.
Reinforce and Review
Copy and distribute the lesson worksheets in the CK-12 Earth Science for Middle School Workbook. Ask students to complete the worksheets alone or in pairs to reinforce lesson content.
Lesson Review Questions
Have students answer the Review Questions listed at the end of the lesson in the FlexBook® student edition.
Check students’ mastery of the lesson with Lesson 8.2 Quiz in CK-12 Earth Science for Middle School Quizzes and Tests.
Points to Consider
What types of evidence would scientists use to determine whether an ancient volcanic eruption was explosive or non-explosive?
Are all volcanoes shaped like tall mountains with a crater on the peak?
What language do you think gives us the names a’a and pāhoehoe?
What changes in the pattern of earthquakes might indicate a volcano is about to erupt?