During the past four months, the June 27 lava flow, named for the date in 2014 that it began erupting from Pu‘u ‘O‘o on Kilauea Volcano’s East Rift Zone, has consisted of small surface pahoehoe flows scattered across a broad area within 5 miles of Pu‘u ‘O‘o.
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 Pu‘u ‘O‘o; the tube beyond this distance became completely inactive in March 2015.
Some surface flows also are being fed from a second, much shorter tube that began forming when the original tube ruptured near its source on Pu‘u ‘O‘o 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 Pu‘u ‘O‘o 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 9-13 acres. Total surface areas of the active flows are calculated using a thermal 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 Pu‘u ‘O‘o 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 of the island of Hawaii. There is no immediate or short-term 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 Pu‘u ‘O‘o 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 are 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 Pu‘u ‘O‘o 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 Pu‘u ‘O‘o — 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 Pu‘u ‘O‘o and Kilauea’s summit on the USGS 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 July 21, when the level dropped in response to summit deflation to about 210 feet, where it remained as of July 23.
Kilauea’s East Rift Zone lava flow continues to feed widespread breakouts northeast of Pu‘u ‘O‘o. Active flows are slowly covering and widening the flow field, but remain within about 5 miles of Pu‘u ‘O‘o.
One earthquake was reported felt on the island of Hawaii this past week. On July 17, at 7:38 p.m., HST, a magnitude-2.6 earthquake occurred 3.9 miles south of the Mauna Loa Summit at a depth of 2.6 km.
Please visit the HVO website (http://hvo.wr.usgs.gov) for past Volcano Watch articles, Kilauea daily eruption updates and other volcano status reports, current volcano photos, recent earthquakes, and more; call (808) 967-8862 for a Kilauea summary update; email questions to askHVO@usgs.gov.
Volcano Watchis a weekly article and activity update written by scientists at the U.S. Geological Survey‘s Hawaiian Volcano Observatory.
