| 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 3, 2006, is a great example of the gas-pistoning that was occurring at that time. The opening is about 8 meters (26 feet) across and is inset within the floor of the Drainhole vent itself, which is about 25 meters (80 feet) across. The images that comprise this video were acquired by a time-lapse camera positioned on the northern lip of the Drainhole vent and about 15 meters (50 feet) away from the opening. The image acquisition rate was 1 frame per minute, and the resulting video is played at 10 frames per second. |
