Aa Surge Run, Hawaii

photo of Aa Surge Run, Hawaii

Volcanologists studying the velocity of an aa surge during an early episode of the Puu Oo eruption of Kilauea Volcano, Hawaii. Most aa flows move rather slowly -- a few meters per hour. Sometimes they thicken rapidly and then surge forward. In this experiment, the flow surged down the steep road about 100 meters in 50 seconds; the volcanologists made the 100 meters in about 20 seconds.

U.S. Geological Survey Photo by Jim Griggs.

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