VISIT THE ACTIVE ERUPTION SITE

July-December 1999

JULY - AUGUST: Things were pretty quiet. Activity continued at the ocean except for a short pause that resulted in some surface flows. Ken went out several times to film lava flows "inflating" or growing thicker as new lava fills them from the inside.


September 12, 1999 - Lava drained from the summit and Pu`u `O`o, producing a swarm of earthquakes as it filled a new underground crack deep beneath the Chain of Craters (east rift zone). Jenda flew out with HVO to investigate. Pu'u 'O'o was empty and quiet, but as the lava drained from the tube system, the lava benches at the ocean began collapsing violently. Jenda caught a few of these collapses and explosions in action (see photos).


September 24, 1999: After waiting nearly 2 weeks, the eruption started up again. During this time, magma probably filled the underground crack in the rift zone and then tried to return to its normal path. The volume of lava coming out was only half of what was being erupted prior to the shut-off. The image at right is an aerial view of lava slowing filling up the Pu'u 'O'o crater once more. Jenda is visible on the rim in the foreground.

September 25, 1999: Lava started flowing again and was trying to reoccupy the old tube system. However, because of the long pause, the tubes were blocked and the lava kept being forced back up to the surface. Jenda and Cheryl went out and filmed one of these surface flows as it poured into a huge old skylight not far from Pu'u 'O'o. It made a very impressive set of lava falls. Photo to left. The skylights eventually filled, overflowed, and built a series of perched ponds that fed new flows. These flows took days to finally reach the pali (the big steep hillside down to the sea).



October 3, 1999: Ken went out on foot to film a'a flows that had reached the base of the pali. These flows were burning trees (see photos) as they advanced through some of the remaining bits of forest and grassland out in the flow field. These flows died out, however, and never reached the ocean.

October 16-17, 1999: Jenda and HVO geologist Dave Sherrod spent a night out at Pu'u O'o. Some of the cones and pits outside the main crater were showing unusual activity - some jetting, spattering, loud booming sounds, and lots of thick sulfur fume. There was even a hole with incandesdent flames rising from it. Scary stuff.

October 25, 1999: Cheryl and Jenda flew out with HVO to see a breakout of large new a`a flows. A series of intertwined channels fed multiple flow fronts that attacked the eastern side of one remaining island of forest. The flows advanced quickly, though as they reached the flatter slope, they slowed down and became slabby pahoehoe flows. From the ground, we could see lots of "lava balls," chunks of channel wall that had fallen into the lava stream and been carried downslope and coated with lava.

NOVEMBER: When the a'a flows reached the base of the pali, they stagnated into slow-moving pahoehoe flows. Another pause in early November stopped these flows within a mile of the ocean. On the day after Thanksgiving, Ken went out and caught some new a'a flows coming down the pali, burning more of the forest. These western flows kept advancing and began to form a new lava tube.


December 5, 1999: Ken was out there again filming some large, fast-moving a'a flows coming down the eastern side of the flow field. These rubbly a`a flows form when lava moves down the steep slopes of the volcano. The rapid movement of the lava through these channels causes the lava to shear or tear into smaller chunks. A'a flows advance like a bulldozer and generally knock down and burn anything in their way. These flows burned another chunk of forest, including the poor tree visible in the video clip below. Choose: avi (420 kb) larger avi (365kb) QT (374 kb)

DECEMBER: Lava finally reached the ocean only a mile walk from the end of the Chain of Craters road in the National Park. From mid-December on, it has poured in, putting on quite a show for visitors.

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