Intro to Volcanoes
Contrary to Hollywood movie
magic where all volcanoes
spew large amounts of lava,
there are two types of volcanic
• Non-explosive eruptions
• Explosive eruptions
• Lava flows: a river of red-hot lava. They
are relatively calm and release large
amounts of molten rock which aid in
forming huge mountains.
• Pyroclastics: Clouds of hot debris and
gas shoot from the volcano. Particles
range from dusts to huge boulders.
Often violently explosive and sometimes
reduces the size of the volcano.
Magma vs. Lava
• What’s the difference?
• Magma is the molten rock inside the
• Lava is magma that has reached the
surface of the Earth, often coming in
contact with air (or water).
• Pyroclastic material is magma and rock
fragments (pieces) that are blasted into
the air by violent eruptions.
More on Magma
• The type of eruption is often due to the
type of magma building up in the magma
chamber. There are two key ingredients to
determining the type of explosion:
• More water usually leads to a greater explosion.
The water often turns to steam and acts similar to
shaking up a soda can.
• More silica also leads to a greater explosion.
Silica is like rock version of glue. It is very sticky
and hardens quickly, often trapping gas inside.
• Brochure project requirement:
1. Title of Volcano, student name
2. Location, Distance from San
3. Type of Volcano/pictures
4. Interesting facts about volcano
5. Safe to visit? Likelihood of an
Some sample choices…
• Mount Kilauea – Hawaii
• Mount St. Helens – Washington
• Mauna Loa – Hawaii
• Mount Pinatubo – Philippines
• Montserrat – Caribbean
• Three Sisters (South Sister) – Oregon
• Mount Fuji – Japan
• Mount Shasta – California
• Lassen Peak – California
• Crater Lake – Oregon
• Mount Baker – Washington
• Mount Rainier – Washington
• Mount Hood – Oregon
• Three Sisters (North Sister) – Oregon