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‘Leaky’ lava tubes spread flows only short distances from Puu Oo

Updated: 
July 26, 2015 - 1:30am

During the past four months, the June 27 lava flow, named for the date in 2014 that it began erupting from Puu Oo on Kilauea Volcano’s East Rift Zone, has consisted of small surface pahoehoe flows scattered across a broad area within 5 miles of Puu Oo.

These flows are fed by countless leaks or lava “breakouts” from the main lava tube. All of the leaks start within about 4 miles of Puu Oo; the tube beyond this distance became completely inactive in March.

Some surface flows are also being fed from a second, much shorter tube that began forming when the original tube ruptured near its source on Puu Oo and sending a lobe of lava toward the northeast on Feb. 21. This younger lobe advanced across older parts of the June 27 flow, and even over the main tube.

The location of the main tube is relatively well known based on thermal (infrared) imagery acquired during many helicopter overflights during the past year, but the path of the second tube is complex and difficult to locate. The many overlapping breakouts immediately north of Puu Oo have obscured its thermal “signature” in the images.

By spawning so many short-lived flows over a large area, the leaky nature of the tubes means that no single flow has been able to capture the volume of lava needed to develop into a sustained, rapidly advancing flow similar to the June 27 flow late last year.

At any one time since late March, the combined surface area of the active flows — leaks from the tubes — has varied between about 9 and 13 acres. Total surface areas of the active flows are calculated using a thermal (infrared) camera and specialized software to stitch together the images and total the hottest areas. The “active” flows are assumed to have surface temperatures greater than about 390 degrees Fahrenheit. Earlier thermal studies of pahoehoe lava flows erupted from Puu Oo indicate that this temperature threshold represents lava flows that were emplaced within about the previous five hours.

This pattern of activity continues to be good news for the Puna District. There is no immediate (weeks) or short-term (months) threat of inundation of residential areas from the current series of flows. The breakouts, especially the one that began Feb. 21, were the main reason the lower part of the June 27 flow became completely inactive in March.

Currently active lava flows are far upslope from the tips of the June 27 flow that reached as far as 14.3 miles from Puu Oo and repeatedly threatened to inundate residential areas, businesses, electric and communication utilities, and Highway 130. For now, the breakouts are mostly filling in low areas on the June 27 flow and only slowly widening and thickening the flow field.

How long might this pattern last?

Veteran volcano watchers accustomed to more than 32 years of changes at Puu Oo know well that the current pattern of lava-flow activity will not last. When and how the activity will evolve is, of course, not known at this time, but a change in the erupting vent on Puu Oo — its geometry or location — would likely result in a change in the flow activity or direction.

In the meantime, keep up to date with the activity at Puu Oo and Kilauea’s summit on the U.S. Geological Survey’s Hawaiian Volcano Observatory website, where updates are posted each morning at http://hvo.wr.usgs.gov/activity/kilaueastatus.php. This update is linked to maps and photographs that are posted following each overflight made by HVO scientists to assess the current activity.

Kilauea activity update

Kilauea’s summit lava lake level remained fairly steady at 167 feet below the vent rim until Tuesday, when the level dropped in response to summit deflation to about 210 feet, where it remained as of Thursday.

Kilauea’s East Rift Zone lava flow continues to feed widespread breakouts northeast of Puu Oo. Active flows are slowly covering and widening the flow field, but remain within about 5 miles of Puu Oo.

Visit the HVO website at http://hvo.wr.usgs.gov for Kilauea daily eruption updates and other volcano status reports, current volcano photos, recent earthquakes and more; call 967-8862 for a Kilauea summary update; email questions to askHVO@usgs.gov.

Volcano Watch is a weekly article and activity update written by scientists at the U.S. Geological Survey‘s Hawaiian Volcano Observatory.

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