Mar 21, 2014: The small (10 meters, or 30 feet, wide) lava pond wit...

Mar 21, 2014: The small (10 meters, or 30 feet, wide) lava pond within the northeast spatter cone on Pu‘u ‘Ō‘ō experiences cyclic rises and falls of the lava surface called "gas pistoning," driven by the buildup and release of gas in the pond. At the time of this photograph, the pond surface had dropped following the release of gas.