Volcanoes 101 | National Geographic

Summary by Krater

This video explains the formation, types, and explosiveness of volcanoes, concluding with how volcanic activity has shaped the Earth's landscape and atmosphere.

From the video

Answers: How do volcanoes form and how are they classified?

• Volcano formation
• Plate tectonics
• Volcanic types
• Magma and lava
• Volcanic Explosivity Index

What it concludes

• Most volcanoes are located where tectonic plates meet, with about 75 percent of them found in the Ring of Fire.
• Volcanoes are primarily classified by shape and size into stratovolcanoes, shield volcanoes, calderas, and mid-ocean ridges.
• Magma forms when heat from the earth's core melts rock, and because it is lighter than solid rock, it rises through the mantle and escapes through vents.
• Pyroclastic flows combine scorching hot gas and ash and can race down the sides of a volcano at speeds up to 100 miles per hour.
• The Volcanic Explosivity Index measures eruptions on a logarithmic scale where each magnitude is ten times more powerful than the one before it.
• Mount Tambora erupted in 1815 with a VEI measurement of 7, causing catastrophic destruction and turning a 13,000 foot tall mountain into a 3,640 foot deep caldera.