Volcano Watch — Kīlauea eruption status, August 11, 1995

The eruption on Kīlauea's East Rift Zone continues with little change. Lava is erupting from two vents located on the south and west flanks of the Pu'u 'O'o cone. Each of these vents is now marked by a large area of collapse; no lava can be seen in the collapse pits over either vent. The lava is transported underground in a tube from the vents to the ocean, nearly seven miles downslope. In the past several weeks, a new large opening, or skylight, has opened in the upper part of the tube. This skylight is at the approximately 2,450 foot elevation, below the point where the two tubes from the vents converge. The view into this skylight reveals a roughly 40-foot wide shallow river of lava about 65 feet below the surface. Since this tube originally formed just below the surface, its present depth provides clear evidence that the tubes cut downward as lava flowed through the tube.

The upper part of the tube system has been remarkably stable during the past several years, but many lava flows have issued from the tube below the approximately 2,250 foot elevation. In the past several weeks, there have been several large breakouts from this section of the tube. Last week, one of them entered the forest to the west of the long, narrow flow which had cascaded over Pulama pali last February during the filming of the JASON Project. By early this week, however, this flow had slowed and did not appear to be a threat to the grasslands along the coastal zone west of the current flow field.

Near the top of Pulama pali, the tube bifurcates, with an eastern tube feeding lava towards Kamoamoa and a western tube feeding lava to a large ocean entry point near the western edge of the flow field, not far from the end of Chain of Craters Road. The eastern tube was transporting lava to the ocean until a few weeks ago; since that time, several moderate-sized 'a'a flows have been fed from this tube. These flows have slowly advanced down the flow field, have been overtopped by pahoehoe flows, and are now approaching Pali'uli near the eastern and central part of the flow field. On Friday morning, the easternmost part of this flow was burning the forest along the east side of the flow field above Pali'uli.

The rim of Pu'u 'O'o continues to be unstable. Sections of the rim have repeatedly collapsed into the crater over the past several months, including one that removed a site where we had been collecting airborne lava samples (Pele's tears and hair) in a box. This past week, the rim adjacent to our sampling site again collapsed, leaving the box, which had been about 15 feet from the rim, a mere five feet from the edge. As the sample box contained abundant Pele's tears, the section of rim that collapsed apparently fell into, and disrupted, the lava pond inside Pu'u 'O'o Crater.

We have recently begun using an infrared camera that can see through the thick fume and steam plume to view the pond inside Pu'u 'O'o. This camera has allowed us to estimate the pond size; it is now no larger than about 100 feet across, compared to a diameter about twice that only a few months ago. This reduction in the size of the pond may indicate that it will crust over completely in the future, as the pond did at the Kupaianaha vent nearly a year before that vent stopped erupting.

In addition to the continuing eruptive activity, Hawaii had two earthquakes that were large enough to be felt this past week. The first occurred deep beneath Kohala Volcano at 9:33 p.m. on Tuesday night. It had a magnitude estimated at 3.0 to 3.5, but was widely felt in the northern half of the island. The second occurred Wednesday night at 9:03 p.m. It was located just south of the Pu'u 'O'o vent at a depth of about five miles and had a magnitude of 3.8. This earthquake was caused by the continuing southward slip of the south flank of Kīlauea Volcano along a deep, nearly flat-lying fault zone. It preceded, by only a few minutes, a series of much smaller earthquakes beneath Leilani Estates that persisted for several hours. For the last several months, we have been recording occasional earthquakes in this region, but leveling, tilt, and global positioning system measurements of the shape of the ground surface in the area do not indicate any significant changes in the area.