One year ago, the now infamous June 27 lava flow was headed toward the middle of Pahoa and threatening to cross the main village road and cut off Highway 130 for thousands of residents. During this time, the U.S. Geological
One year ago, the now infamous June 27 lava flow was headed toward the middle of Pahoa and threatening to cross the main village road and cut off Highway 130 for thousands of residents. During this time, the U.S. Geological Survey’s Hawaiian Volcano Observatory was forecasting that, if the flow continued, it could also cut Kahakai Boulevard and overrun Keonepoko Elementary School.
Fortunately, at the same time, the supply of lava from the Puu Oo vent on Kilauea Volcano’s East Rift Zone was decreasing. Tiltmeters at the summit of Kilauea were recording a deflationary trend, which suggested that less magma from the summit reservoir was getting to Puu Oo and, ultimately, that less lava was reaching the flow front in Pahoa.
As a result, the tip of the flow stalled about 170 yards from Pahoa Village Road on Oct. 30, 2014. This was because lava was no longer traveling through the tube all the way to the flow front. The delicate balance of lava supply needed to continue growing the lava tube had tipped to the town’s favor.
The stalled front and apparent clogging of the lowermost part of the tube instead resulted in upslope breakouts of lava, spawning numerous surface flows that widened the flow field in the following weeks.
Before the June 27 lava flow became a threat, many people in the Puna District — long-term residents and recent arrivals alike — were unfamiliar with the vocabulary of volcanology. Summit deflation and inflation, lines of steepest descent, lava breakouts, and flow advance rates were just abstract concepts initially. But residents quickly became well-versed in these terms, making it easier for them to realize the unpredictable nature of slow-moving pahoehoe flows.
As the lava flow approached Pahoa, the questions asked by the community were difficult to answer with certainty and required full explanations instead of short soundbites.
How far would the flow eventually travel? When will lava arrive at this or that location? How wide will the flow spread? How long will Puu Oo erupt lava into the tube? Is “my” house going to be covered by lava? How will scientists know when the June 27 flow will stop?
HVO scientists answered these questions and shared new information about the flow in all kinds of ways. They provided written updates, images and maps of the flow’s activity, location and likely flow path(s) on the HVO website at hvo.wr.usgs.gov, and responded to hundreds of individual questions by telephone and email through askHVO@usgs.gov.
But perhaps most importantly, nearly all of HVO’s staff, at one time or another, participated in dozens of Puna District community meetings that were organized by the Hawaii County mayor’s office between Aug. 24, 2014, and Jan. 22, 2015.
At these meetings, HVO summarized the flow activity and discussed lava flow behavior, Hawaiian volcanism, and volcano hazards through an illustrated slide presentation. Afterwards, HVO staff interacted with residents through one-on-one discussions at map stations set up around the room.
Without a doubt, these meetings were vital for HVO scientists, emergency management officials, business leaders, community organizations, elected government representatives, and hundreds of residents at a time to listen to each other. Through these interactive discussions, people developed a common language, which helped everyone better understand the flow activity and the ways in which response plans were being developed and implemented. Online broadcasts of the community meetings allowed even more people to listen in.
The meetings helped Puna communities to appreciate the challenges and uncertainties HVO scientists faced in trying to forecast lava-flow paths and advance rates. Residents were able to speak directly with scientists, emergency managers and representatives from other government agencies about the lava flow activity and their individual concerns. Everyone was able to learn of plans for the worst-case scenario, all the while hoping for the best possible outcome.
The Puna Resiliency Block Party in Pahoa this past weekend was welcomed by HVO scientists as a time to visit once again with Puna residents, and to talk about Kilauea’s eruptions and ongoing hazards, as well as Mauna Loa’s recent unrest. It was also a reminder of the ways in which the community meetings helped us develop a common volcano language and understanding.
Volcano activity updates
Kilauea continues to erupt at its summit and East Rift Zone. The summit lava lake level varied between 180 and 240 feet below the vent rim within Halemaumau Crater. On the East Rift Zone, scattered lava flow activity remained within about 4.3 miles of Puu Oo.
Mauna Loa is not erupting. During the past week, earthquake rates continued to be elevated above background levels, though at a lower weekly rate than recorded in late summer. Deformation data remain consistent with inflation of magma reservoirs within the volcano.
There were no earthquakes reported felt on Hawaii Island this past week.
Visit the HVO website at hvo.wr.usgs.gov for Kilauea daily eruption updates, Mauna Loa weekly updates, volcano photos and recent earthquakes information; call for summary updates at 967-8862 (Kilauea) or 967-8866 (Mauna Loa); 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.
