Miscellaneous Volcanic Facts,
Questions, and Answers

General Volcano Information

• What is a volcano?
• Where did the term "volcano" come from?
• What is an "eruption" ?
• How much of the Earth is volcanic?
• How many active volcanoes are there in the world?
• What is the "Ring of Fire"?
• How many people are affected by volcanic eruptions?
• What are some positive products from volcanoes?
• Where is the largest active volcano in the world?
• What was the largest volcanic eruption in the 20th century?
• What was the most destructive volcanic eruption in the history of the United States?
• Where in the United States is there evidence of volcanism?
• Where does the United States rank in the number of volcanoes?
• TRUE or FALSE: Portland, Oregon, has a volcano within its metropolitan area?
• What GOOD is a volcano?

Cascade Range Volcanoes

• What is the extent of the Cascade Range?
• What are the major peaks of the Cascade Range?
• How many eruptions have there been in the Cascades during the last 4,000 years?
• How many eruptions have there been in the Cascades during the last 200 years?
• Which is the tallest volcano in the Cascades? Is it also the largest?
• Which Cascade Range volcano erupted through a glacier?
• Which is the most glaciated volcano in the Cascades? Which is the second?
• How dangerous is Mount Rainier?
• What is the greatest hazard presented by Mount Rainier?
• How often do giant debris flows occur at Mount Rainier?
• How would an eruption of Mount Rainier compare to the 1980 eruption of Mount St. Helens?
• How old is Mount St. Helens?
• Where did the name "Mount St. Helens" come from?
• How high was Mount St. Helens before the May 18, 1980 eruption. How high was it after?
• How much ash was there from the May 18, 1980 eruption of Mount St. Helens?
• How far did the ash from Mount St. Helens travel?
• How did Mount Hood get its name? How tall is it?
• Are there earthquakes associated with Mount Hood?
• What are the "Three Sisters"?
• Which is the oldest of the Three Sisters?
• Which Cascade volcano has a "volcano in a lake in a volcano"?
• How often does Mount Shasta erupt?
• When did Lassen Peak last erupt?
• Where is Dante's Peak located?
• Is Mount Wilshire a real volcano?

Alaskan Volcanoes

• How many volcanoes are there in Alaska?
• How often do Alaskan volcanoes erupt?

Hawaiian Volcanoes

• What are the "Hawaiian Islands"?
• How many major Hawaiian Islands are there? What are their principal volcanoes?
• How big are the Hawaiian volcanoes?

Volcanic Features and Phenomena

• What is a "composite" or "strato" volcano?
• What is a "shield" volcano?
• What is a "caldera"?
• What causes earthquakes?
• Can I outrun a debris avalanche?
• What is a "pyroclastic flow"? Where did the term come from?
• How dangerous are pyroclastic flows?
• What is the difference between "magma" and "lava"?
• Can volcanic rocks float?
• What is a "lava dome"?
• What is "volcanic ash"?
• What is a "lahar"?
• How big are lahars?
• How are lahars formed?

• RETURN -20th Century Volcanic Eruptions and Their Impact
• NEXT - "Learn About Volcanoes" Menu