View into the inner crater vent of Pu`u `O`o from the north crater rim. The inner crater is about 60 m in diameter. Minutes before this photograph was taken, the top of the lava column had risen sufficiently to spill outward from its inner rim and partly cover the crater floor (lower left). In this photograph, the lava is draining back into the inner crater vent and a low lava fountain forms as gas escapes from the churning mass of molten rock. A few minutes later, the lava column subsided to a depth of about 10 to 15 m, the depth at which it has persisted for the past few weeks.