Supervolcano map (CCA: A Learning Family).

The term supervolcano usually refers to a huge explosive eruption. This eruption releases a large amount of material into the atmosphere and earth’s surface. These massively explosive eruptions are capable of modifying the earth’s climate.

Map: Major supervolcanoes (CCA: A Learning Family).

The Supervolcano

The Volcanic Explosivity Index (VEI) is a measure of how violent an eruption is. An eruption with a scale of VEI 8 throw out at least 1,000 cubic kilometers of material. VEI 7 events release at least 100 cubic kilometers of material.

The map above displays volcanoes in the VEI 7 to VEI 8 range. The map reveals that these volcanoes are almost entirely located on the outer rim of the Pacific Ocean. This ring of volcanic activity is commonly called the Pacific Ring of Fire. This ring stretches north from New Zealand, to Japan and to Alaska. It then curves south from Alaska, to North America and then to South America.

The Resulting Caldera

A large caldera (crater) is often created by a VEI 7 or VEI 8 eruption. These eruptions occur quickly and eject a large amount of material into the atmosphere and earth’s surface. As the molten magma is quickly withdrawn from the earth, the overlying rock collapses into the now empty magma chamber.

Improving Your Reading and Thinking Skills

Think for a few moments. Try to recall the major ideas in this article. When you are done, click the box below for a list of main ideas.


How did you do? With practice, you should be able to identify many of the major ideas. You may even discover some important ideas that aren’t listed.


Volcano Hazards Program, US Geologic Service.