Volcano Watch — Kīlauea eruption status, October 13, 1995

During the past few weeks, we took a break from writing about Kīlauea's East Rift Zone eruption to explore the geological history of the main Hawaiian Islands and to bring you up-to-date on the eruption at Ruapehu Volcano in New Zealand.

Kīlauea, however, did not take a break, as the eruption has been continuous since the last pause in activity between August 22 and 25. After the pause, flows broke out of the old tube system at numerous locations below about the 2,250-foot elevation and advanced down the eastern side of the Kamoamoa flow field.

When we last described the activity on September 1, the flows had advanced down to the coastal plain, and we predicted that they would reach the ocean within the next week. Right on cue, the first ocean entry became established on September 7 at about 7:20 p.m. at Kamokuna, a point between the Waha'ulu and Kamoamoa flow fields.

Since that time, the activity has been concentrated along the eastern side of the Kamoamoa flow field. Lavahas now resurfaced much of the area below Pulama Pali on the east side, covered coastal grasslands, and threatened a spot where we had a seismic station, which we were forced to move. A main tube has become established that delivers lava to the ocean at Kamokuna, but numerous surface flows have continued to break out of the tube system near the top of Pulama Pali and along its steep slope.

By September 8, there were three distinct coastal entry points and since then, there have usually been three or more entries. These entries form and then die, only to have another form nearby. Only the main entry at Kamokuna has remained active throughout the period.

There have also been some changes in the upper part of the volcanic system at, and near, Pu'u 'O'o. The pond inside the crater is now smaller and deeper than it previously was; most of the time, the pond is only 50 feet across and is about 325 feet below the lowest part of the crater rim. Despite the small size of the pond, on clear nights, a strong glow is visble above the Pu'u 'O'o cone.

Additional changes have occurred in the area where the episode 51 vents were located. This region had collapsed several years ago, but during the week of September 21, an additional collapse occurred that created a deep inner pit. On September 28, a red glow could be seen through the thick volcanic fume in the pit.

The uppermost section of the tube system has also developed a spectacular new skylight at about the 2,450-foot elevation. This skylight allows us to see into the tube that is carrying the lava to the breakouts downslope. The opening is more than 10 feet across and provides a view of the slowly flowing lava river, nearly 100 feet below the surface. This river is about 35 feet wide but is moving so slowly that its speed does not register on the radar gun we use to measure flow rates. We have been observing the changes in the shape and size of this tube for about two months.

On September 11, both the U.S. Geological Survey's Hawaiian Volcano Observatory and Hawai'i County Civil Defense received numerous phone calls reporting that the plume from Pu'u 'O'o was darker than normal. The plume apparently looked different that day because of the light Kona wind conditions which sent the plume straight up.

The lava entries are now visible from the end of Chain of Craters Road inside Hawai'i Volcanoes National Park, although they are several miles from the nearest viewing point. Surface flows continue to cascade down Pulama Pali; these flows are also visible from the end of the road, particularly at dusk and after dark.

All the usual hazards exist where lava is entering the ocean, including instability of the lava benches, acidic fume, methane explosions from burning vegetation where flows are covering previously uncovered ground. In addition, the several-mile hike across the flow field crosses a long stretch of new hot flows. For these reasons, the National Park Service has closed the area beyond the end of Chain of Craters Road.

At some future time, when the activity is once again near the end of the road, closer lava viewing will be available to the public.