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August 24, 2000

A weekly feature provided by scientists at the Hawaiian Volcano Observatory.

Kilauea's Eruption Changes; Ocean Entry Stops

The past two weeks have seen changes in Kilauea's eruption. The changes aren't fundamental, but they do impact the viewing public. The ocean entry has stopped, surface flows no longer can be seen on the coastal flat, and a bright glow sometimes highlights the sky above Pulama pali.

The changes began on August 12, with outbreaks of lava from the tube system at the 2,250-foot elevation between Pu`u `O`o and the top of Pulama pali. At that time, a GOES satellite image showed hot spots that were confirmed before dawn the next morning by glow visible from the Chain of Craters Road.

On the afternoon of the 15th, lava began to emerge from higher on the tube at the 2,300-foot elevation. One flow headed directly south but had died out at about 2,150 feet when next seen a week later. The other moved southeastward, along the trace of flows active earlier in the year. At least the southeastern flow remained active for the rest of the week, but observations over the weekend were poor and inconclusive. All during this time, the ocean entries provided beautiful shows and showed no signs of lessening.

Predawn observations on Monday, August 21, showed that the ocean entry at Waha`ula was continuing, though weakly. Dominating the scene was rosy glow coming from along the trace of the active lava tube well north of Pulama pali. Around noon, observers reported a very weak to nonexistent steam plume from the Waha`ula area, and no other evidence of active entry. Later that afternoon, the plume died out completely, with only wisps remaining.

On Tuesday, helicopter observations showed that the two breakout points remained active. The southeastern flow from the 2,300 breakout point reached at least as low as 2,100 feet. There it was overrun by a second breakout, which began at 2,175 feet and moved along the eastern margin of last spring's flow (the Smoke flow) down to nearly 1,800 feet. This breakout is active along much of its length and accounts for most of the night-time glow.

The two eastern flows have each burned through a few small kipuka. The combined length of both flows is about 3.3 km (2 miles). If the larger flow continues, it will probably turn south, hemmed in to the east by thick `a`a flows of an earlier stage of the eruption, and will not endanger Royal Gardens.

No lava was visible at a skylight in the tube south of the breakout points. Apparently a blockage had formed in the tube near the breakout points, presumably by cave-ins of the roof or walls of the tube. Lava formerly flowing in the tube is now diverted to the surface by the blockage. With lava supply cut off, the tube drained, and the ocean entries and coastal surface flows slowly shut down.

What are the consequences of this turn of events? For now, there will be no viewing of lava entering the ocean. Most likely a new lava tube will eventually replace the one that has been supplying lava to the coast. At this writing, the tube has been empty for less than a week, however, so there is still a chance that the tube will be reoccupied if it doesn't collapse as it cools. If not, the development of a new tube or tube system will probably take weeks or months. Then, surface flows will slowly make their way down the pali and across the coastal flat, crusting over and creating tubes in the process. Not until those flows reach the coast would there be any of the beautiful entry viewing that we have come to expect these past several months.

There were no felt earthquakes on the island during the past week.

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Updated: September 11, 2000