Volcano Watch — Skylights mark current Kīlauea lava flows

The 10-year-long eruption on Kīlauea's East Rift Zone continues with lava flowing from the vents on the south and west sides of Pu`u `O`o to the sea in underground tubes.

There are now two lava entries on the east and west sides of the Kamoamoa lava delta. The lava tube is characterized by a sequence of skylights from 2,350 feet to about 200 feet above sea level.

Skylights are openings in the top of the tube, where the roof has either collapsed or been pushed upwards by magma pressure within the tube, and can be identified from a distance by plumes of bluish fume.

Over the last week, a large `a`a flow was fed from a skylight located at about 1,820 feet elevation; this flow advanced down the pali, covered much of a heavily vegetated kipuka, and finally stopped at the 750-foot elevation. This was the largest `a`a flow to have occurred in many months.

On June 29, a large, fluid sheet flow leaked from the lava tube on the Kamoamoa delta. The point of origin was near the original coastline, which is now located about 0.4 miles inland from the present coastline. This sheet flow rapidly advanced to the sea and built a small lava delta before the flow stopped. A small flow has been intermittently active on the west side of the lava flow field above Paliuli near Lae`apuki.

The Park Service has cut a trail to the area for viewing by visitors. However, due to the intermittent character of this flow, it is wise to check at the Visitor Center in Hawai`i Volcanoes National Park or with rangers on duty near the end of Chain of Craters Road in the park.

During the last two weeks, there was a major and several minor collapses of the lava bench adjacent to the ocean where the lava enters the water. The largest occurred on Saturday, July 3, when most of the youngest bench of lava at the main Kamoamoa entry slid into the sea during the early morning. For much of that day, lava fountains and steam explosions built a new spatter cone at the point where lava entered the sea and scattered angular blocks over nearby lava flows. This bench collapse took place at about the same time that the `a`a flow started from the skylight at 1,820 feet elevation and coincided with a decrease in flow rates through the tube system.

The eruption rate, as determined by measuring the flow rate and cross-sectional area of the tube at several locations, has fluctuated significantly during the past several months, with maximum fluxes of about 420,000 cubic yards per day and minimum fluxes of about half that amount. This variable flux from day to day has led to instability in the tube and the many small flows emanating from the skylight.

On Thursday, there was little to see at the two ocean entries, because the lava pours directly into the sea, and the interaction is veiled in steam. In addition, steam explosions, collapse of the lava bench, and acidic fume all pose serious hazards in the area. For these reasons, the Park Service has closed this area to visitors. For your own safety, obey the area closure signs posted in the area.

The pond inside Pu`u `O`o cinder cone has risen about 65 feet to about 243 feet below the rim in the last two weeks, but the surface is less active than when the pond was deeper.

There have been no earthquakes with magnitudes larger than 3.0 within the last two weeks anywhere in the Hawaiian Islands.