Gas-Pistoning at Drainhole Vent in Pu'u 'O'o Crater (June 28, 2006)

Gas-pistoning is an interesting phenomenon seen at Kilauea and other volcanoes. It is caused by the accumulation of gas within, or the rise of a gas slug through, a column of lava. In either case, the gas pushes up the overlying lava (the "piston"). Eventually, the gas breaches the surface and escapes, sometimes as a forceful jet of fume and spatter. The lava then drains back into the vent. Gas pistons can occur as single events or as a repeating series comprised of dozens or even hundreds of events. During mid-2006, eruptive activity at the informally-named Drainhole vent, on the floor of Pu'u 'O'o crater, was often characterized by periods of gas-pistoning. The video sequence shown here, from June 28, 2006, is a great example of the gas-pistoning that was occurring at that time. The Drainhole vent from this angle is about 20 meters (65 feet) across.

The images that comprise this video were acquired by a time-lapse camera positioned on the northwestern edge of the Drainhole vent. The image acquisition rate was 1 frame per minute, and the resulting video is played at 10 frames per second.