This near-vertical view reveals a vigorously bubbling lava surface below the rim of the vent within Halema`uma`u crater.
USGS HVO News Release September 5, 2008
For the first time since the new vent opened in Halema'uma'u Crater on March 19, HVO scientists in a helicopter hovering over the crater were able to see the surface of a sloshing 50 m (160 ft) diameter lava lake about 100 m (330 ft) below the vent rim. HVO scientists have speculated that a lava pond existed a few hundred meters below the vent, but have not been able to get visual confirmation until this morning.
A second viewing early this afternoon revealed a roiling pond with multiple bursting bubbles changing into a central upwelling circulation pattern. The lake level dropped slightly before the cycle restarted. This behavior has been witnessed before, most recently in Pu'u 'O'o vents and the July 21 lava ponds on Kilauea's east rift zone, and is known as "gas pistoning." One model explains pistoning as small gas bubbles coalescing into larger bubbles beneath a crust on a lava pond, rising to the surface, and then bursting. The released pulse of hot gas carries rock dust from the collapsing vent walls, bits of the lava lake crust, and small amounts of spatter.
The Halema'uma'u vent has produced six significant explosive eruptions in the past 5.5 months, most recently on September 2, 2008 at 8:13 p.m. H.s.t., during which noteworthy amounts of fresh lava spatter and lithic material (rock fragments and dust) were ejected on to the crater rim. Just prior to this event, incandescence from the vent was almost nonexistent except for brief pulses of glow.
Click here to post comments.