Book 12, Question 100
How Do Volcanic Landscapes Keep Changing?
Volcanic landscapes are always changing! New rock arrives, old rock wears away, and life moves in. That makes volcano country feel alive, because it never stops changing.
More fun facts
- After an eruption, rain and melting snow easily erode loose ash and rock from hill slopes and quickly carve broad channels.
- At Okmok caldera in Alaska, rivers carved channels into a once smooth ash surface within 5 years after the 2008 eruption.
- Rivers can carry enormous amounts of volcanic sediment to places tens of kilometers downstream, raising riverbeds and causing more frequent flooding.
- From October 1980 to September 2018, the Toutle River near Mount St. Helens carried more than 248 million tons of sediment.
- In 1987 engineers built a sediment retention structure across the North Fork Toutle River to trap sediment before it reached the Cowlitz and Columbia Rivers.
- So many rocks keep falling into the summit crater at Kilauea that rubble from the rim and walls once filled a vent there.
Sources: U.S. Geological Survey, U.S. Geological Survey, U.S. Geological Survey
Questions kids ask
Do volcanoes keep changing even when they are not erupting?
Yes. Rain, rivers and rockfalls keep moving ash and rock for years, even decades, after an eruption.
How long did Mount St. Helens keep sending mud down its rivers?
For decades. The Toutle River carried more than 248 million tons of sediment between 1980 and 2018.