The June 27th Flow Advances Toward Pāhoa
The following is this week’s edition of “Volcano Watch” from the USGS Hawaiian Volcano Observatory:
In an August 22, 2014, news release, the USGS Hawaiian Volcano Observatory (HVO) stated that a new lava flow, dubbed the June 27th flow for the date it began, was rapidly advancing toward residential areas near Pāhoa in the Puna District of the Island of Hawaiʻi. By that time, the flow had entered a pre-existing ground crack, which channeled the flow to the east. The crack eventually filled and lava emerged from its lower end, only to spill into an adjacent crack. This process was repeated several times over the following days, with some ground cracks capturing and directing the flow, while others were simply filled as the lava advanced across them. The average advance rate for the flow during this period was about 250 meters per day (820 feet per day).
By September 4, the flow had advanced to within 1.3 km (0.8 mi) of Kaohe Homesteads, prompting HVO to elevate the Alert Level Code from “WATCH” to “WARNING” to draw attention to the increased threat (http://volcanoes.usgs.gov/activity/alertsystem/).
The June 27th flow filled and exited the last major crack in its path on September 6, when lava turned north as it escaped the system of cracks, faults, and grabens (down-dropped blocks) that had channeled its advance within Kīlauea Volcano’s East Rift Zone. Thereafter, the flow began to move steadily forward as a surface flow, bypassing the south portion of Kaohe Homesteads. With this change in direction, however, the June 27th flow picked up speed and began to travel at about 400 meters per day (0.25 miles per day).
The flow narrowness and rapid development of a robust tube system within subsurface cracks make the June 27th lava flow unique among the hundreds of lava flows that Puʻu ʻŌʻō has erupted. Our best estimates suggest that the tube is transporting about 300,000–400,000 cubic meters per day (55,000–73,000 gallons per minute) of lava to the flow. This is approximately the long-term average eruption rate for Puʻu ʻŌʻō over its 31-plus year eruptive history.
To forecast where this lava flow could go in future days, HVO has calculated downslope paths using a digital elevation model (DEM). These paths are identified as blue lines in most of the recent maps posted on the HVO website (http://hvo.wr.usgs.gov/maps/). Which path the flow might follow becomes more obvious as the flow advances across the Puna terrain.
By September 11, the flow had veered to the northeast and was headed toward the northwest edge of Kaohe Homesteads. If the flow continues, HVO forecasts that the flow will cross Pāhoa Village Road about 1.2 km (0.7 mi) toward the center of Pāhoa from the Pāhoa Marketplace on or around September 24-26.
HVO is working closely with Hawaiʻi County Civil Defense (HCCD) to monitor the June 27th flow. HVO scientists are participating in public Community Meetings in Pāhoa, as well as in meetings with County and State Departments to provide the best information possible during this time.
Daily Kīlauea eruption updates describing conditions for the entire volcano are posted on the HVO website every morning (http://hvo.wr.usgs.gov/activity/kilaueastatus.php). In addition, HVO monitoring flights are conducted each Monday, Wednesday, and Friday to map the flows, assess their hazards, and acquire photos and infrared video. HCCD Administrator Darryl Oliveira also flies over the lava flow every morning and posts a daily update at http://www.hawaiicounty.gov/active-alerts/.
The HVO and HCCD information is compiled into maps that are posted after each HVO overflight at http://hvo.wr.usgs.gov/maps/. Photos and videos of the lava flow are posted at http://hvo.wr.usgs.gov/multimedia/.
HVO’s website also offers a limited ability to view the June 27th lava flow on webcams (http://hvo.wr.usgs.gov/cams/region_kier.php). When conditions are clear, the distant smoke plume can usually be seen in the Puʻu ʻŌʻō North Flank (PNcam) image, although the June 27th flow front is quite far away. The Mobile Cam 3 (R3cam) is also pointed toward the flow front and usually shows smoke during the day and glow at night from the flow front and nearby breakouts.
We encourage Puna residents to stay informed about the lava flow. We all can hope for the best, but must also plan for the worst.