Breakouts remain active northeast of PuÊ»u ʻŌʻō, but on today’s overflight we observed a decrease in overall activity. In particular, breakouts that had been active closer to PuÊ»u ʻŌʻō on previous days, around PuÊ»u KahaualeÊ»a, were inactive today. The active breakouts began about 4 km (2.5 miles) northeast of PuÊ»u ʻŌʻō and reached nearly 8 km (5 miles). This farthest distance has not changed significantly in recent weeks. This photograph looks west along the East Rift Zone, towards PuÊ»u ʻŌʻō and KÄ«lauea’s summit. PuÊ»u ʻŌʻō can be seen near the horizon, on the left side of the image. The farthest active lava today was near the smokey area in the left side of the image. KÄ«lauea’s summit plume can be seen in the distance in the upper right portion of the photograph. Photo taken Thursday, July 23, 2015 courtesy of USGS/HVO

A closer look at the north margin of the June 27th lava flow, where breakouts are active at the forest boundary. Photo taken Thursday, July 23, 2015 courtesy of USGS/HVO

Breakouts have further buried Puʻu Kahaualeʻa in recent weeks. The cone was originally covered in thick vegetation, but today only a single dead tree stands on the remnants of the cone rim. Photo taken Thursday, July 23, 2015 courtesy of USGS/HVO

An HVO geologist collects a sample of lava, quenching it in a bucket of water. Chemical analysis of the lava provides insight into changes in the magma plumbing system. Photo taken Thursday, July 23, 2015 courtesy of USGS/HVO

Time-lapse movie of Pu’u ‘O’o Crater North Flank from the North Rim. July 24, 2015. Images courtesy of USGS/HVO

Time-lapse movie from images gathered from a temporary thermal camera looking into Pu’u ‘O’o Crater. The temperature scale is in degrees Celsius up to a maximum of 500 Celsius (932 Fahrenheit) for this camera model, and scales based on the maximum and minimum temperatures within the frame. Thick fume, image pixel size and other factors often result in image temperatures being lower than actual surface temperatures. July 16-24, 2015. Images courtesy of USGS/HVO

(Volcano Watch is a weekly article written by scientists at the U.S. Geological Survey’s Hawaiian Volcano Observatory.)

Top image shows the forested PuÊ»u KahaualeÊ»a cone on July 18, 2014, surrounded by the June 27th lava flow (light gray surfaces) with PuÊ»u ʻŌʻō in distance. Below, what remains of the PuÊ»u KahaualeÊ»a cone on July 23, 2015, with only the very top of the cone visible. “Leaks” from the lava tube system of the June 27th flow have nearly buried the cone in the past few weeks. Before the PuÊ»u ʻŌʻō eruption began in 1983, the cone was nearly 30 m (100 ft) tall. It formed during an eruption a few hundred years ago, and continued breakouts from the tube will probably bury it completely in the coming weeks. USGS photos.

During the past 4 months, the June 27th lava flow, named for the date in 2014 that it began erupting from Puʻu ʻŌʻō on Kīlauea Volcano’s East Rift Zone, has consisted of small surface pāhoehoe flows scattered across a broad area within 8 km (5 mi) of Puʻu ʻŌʻō.

These flows are fed by countless leaks or lava “breakouts” from the main lava tube. All of the leaks start within about 6 km (4 mi) of PuÊ»u ʻŌʻō; the tube beyond this distance became completely inactive in March 2015.

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 Puʻu ʻŌʻō and sending a lobe of lava toward the northeast on February 21. This younger lobe advanced across older parts of the June 27th 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 PuÊ»u ʻŌʻō 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 27th 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 3.6 and 5.3 hectares (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 200 degrees Celsius (390 degrees Fahrenheit). Earlier thermal studies of pāhoehoe lava flows erupted from PuÊ»u ʻŌʻō indicate that this temperature threshold represents lava flows that were emplaced within about the previous 5 hours.

This pattern of activity continues to be good news for the Puna District of the Island of Hawai‘i. 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 February 21, were the main reason the lower part of the June 27th flow became completely inactive in March.

Currently active lava flows are far upslope from the tips of the June 27th flow that reached as far as 23 km (14.3 mi) from Puʻu ʻŌʻō 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 27th 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 Puʻu ʻŌʻō 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 Puʻu ʻŌʻō—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 Puʻu ʻŌʻō and Kīlauea’s summit on the USGS Hawaiian Volcano Observatory (HVO) 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.

This map shows recent changes to Kīlauea’s active East Rift Zone lava flow field. The area of the flow on July 7 is shown in pink, while widening and advancement of the flow as of July 23 is shown in red. The yellow line is the active lava tube system. Puʻu ʻŌʻō lava flows erupted prior to June 27, 2014, are shown in gray.

This map overlays a georeferenced thermal image mosaic onto the flow field change map to show the distribution of active and recently active breakouts. The thermal images were collected during a helicopter overflight of the flow field on July 23. The June 27th flow is outlined in green to highlight the flow margin. The yellow line is the active lava tube