Kilauea’s tube system springs a few leaks

In recent weeks, new lava flows have broken out from the active lava tube system between the Pu`u `O`o vent and the ocean. These include a brief but spectacular flow over the sea cliff at the coast and — for the first time since early February — a long `a`a flow on Pulama pali.

When observed by scientists on June 30, the flow on the pali had reached the 275-m (900-ft) elevation. A narrow `a`a flow with a central channel of molten lava advanced rapidly through the hummocky terrain of shiny pahoehoe flows on the steep pali. Called the Campout Flow, it was about 4 km (2.5 miles) from the coast.

The source of this flow is a breakout from the active lava tube system 1 km (0.6 miles) south of the Pu`u `O`o vent. Many breakouts have occurred in this area in the past few months, but this one really gained steam about two weeks ago, when it advanced 1.2 km (0.7 miles) in less than a week and continued to flow over the pali by the end of June.

Meanwhile, down at the coast, on the evening of June 24, a large flow broke out of the lava tube just inland of the sea cliff. The breakout started at 8:49 p.m. and, within a minute, formed a brilliant cascade of lava over the 20-m-high (65-ft-high) sea cliff onto the bench below.

By the next morning, fresh lava flows dribbled into the surf at numerous points along the 1,900-m-long (6,235-ft-long) front of the bench. Instead of the usual one or two large plumes billowing skyward, a low curtain of steam and gas was formed.

The breakout could have been caused by a small surge in the lava supply from the vent on the southwest flank of Pu`u `O`o that feeds the lava tube. It could also have been caused by clogging of the tube on the bench, forcing lava to back up and leak onto the surface.

The tube supplying lava to these breakouts and to the active lava bench at the coast originated as a series of flows from the southwest flank of Pu`u `O`o on Prince Kuhio Kalaniana`ole’s birthday in March 2004. These flows eventually formed a tube — the PKK tube — that extended all the way to the ocean and became the main tube by August 2004.

Lava has been entering the ocean at East Lae`apuki since May of 2005. On November 28, 2005, this was the site of the largest bench collapse since lava flows from the current eruption began entering the ocean in 1986. The entire bench, which had attained an area of 17.8 ha (44 acres), collapsed over a period of 4.5 hours.

The bench currently exceeds the size of the November bench, with an area of about 22 hectares (54 acres).

Activity Update

This past week, activity levels at the summit of Kilauea Volcano have remained at background levels. The number of earthquakes located in the summit area is low (usually less than 10 per day that are large enough to locate). Widening of the summit caldera, indicating inflation, appears to have resumed after pausing earlier in April.

Eruptive activity at Pu`u `O`o continues. On clear nights, glow is visible from several vents within the crater. Lava continues to flow through the PKK lava tube from its source on the flank of Pu`u `O`o to the ocean, with surface flows breaking out of the tube at the 2,300-2,200-ft elevation. The most persistent of these flows is the “Campout breakout,” which has advanced to the 500-600-ft elevation.

Lava is still entering the ocean at East Lae`apuki, in Hawai`i Volcanoes National Park. The lava bench continues to grow following the major collapse of November 28, 2005, and is now approximately 1,100 m (3,600 ft) long by 350 m (1,150 ft) wide, with a total surface area of 22 ha (54 acres).

Access to the sea cliff near the ocean entry is closed, due to significant hazards. The National Park has reopened the surrounding area, however. If you visit the eruption site, check with the rangers for current updates, and remember to carry lots of water when venturing out onto the flow field.

There was one earthquake beneath Hawai`i Island reported felt within the past week. A magnitude-2.0 earthquake occurred at 4:44 a.m. H.s.t. on Saturday, July 1, and was located 9 km (5 miles) southeast of Waikoloa at a depth of 17 km (10 miles).

Mauna Loa is not erupting. During the past week, earthquake activity remained low beneath the volcano’s summit (one earthquake was located). Extension of distances between locations spanning the summit, indicating inflation, continues at slow rates.

This article was written by scientists at the U.S. Geological Survey’s Hawaii Volcano Observatory and is republished by with permission.

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