Hawaiian Volcano Observatory scientists confirmed Sunday that rates of seismicity and summit deformation have decreased, as has lava output from fissure 8.
HVO geophysicist Jim Kauahikaua said the number of earthquakes have dropped considerably since before the most recent summit collapse event, which occurred shortly before noon on Thursday.
“Typically, it was between 25 and 35 earthquakes per hour in the summit area, and now we’re down to under five, and usually under two per hour,” Kauahikaua said. He described those earthquakes as “very small.”
Tina Neal, HVO’s scientist-in-charge, said “it’s too early to tell” if the downturn in seismic activity and lava output means an end is in sight to the current eruption along Kilauea’s lower East Rift Zone, which started on May 3. She also noted a significant increase in gas emissions from Pu‘u ‘O‘o vent on Friday.
“It could be weeks or months before we feel comfortable calling the eruption and the summit collapse over,” Neal said. “… It’s not uncommon for eruptions to wax and wane. So this could turn around at any point and resume. We’ll just have to wait and see.
“We’re trying to compare what is going on now with the 1955 and ’60 eruptions. In 1955, there were two long pauses in that eruption. It wasn’t a perfect analogy to this event; there are some differences. In 1955, there were breaks of five and 16 days where it was quiet, and then it broke out again.”
“I’ve had a few calls as far as people wondering if it’s over, and I’ve told them no,” added county Civil Defense Administrator Talmadge Magno. “Especially people in Leilani, because it’s quiet near the fissure and they’re wondering what’s going on.”
Kauahikaua said fissure 8, situated in Leilani Estates subdivision, is “still erupting” but the lava pond within the crater is “partially crusted over … and then, the spillway itself is crusted over.”
“That doesn’t mean there’s no flow out along the channel,” he explained. “… There are still small flows active as far down as Kapoho Crater, but they haven’t gone very far and they’re not very active.”
The ocean entry remained active at the site of the former Ahalanui Beach Park on Sunday. It was noted during HVO’s 6 a.m. overflight there were a few sluggish seeps and ooze-outs near Halekamahina and Kapoho Crater. Lava also continued to ooze into the ocean along a broad flow front and laterally toward Pohoiki but was still about 230 feet southeast of the boat ramp.
Kauahikaua said despite the decrease in lava being churned out by the fissure “it’s still possible” the boat ramp — which has been within a proverbial stone’s throw of an edge of the flow front for about three weeks — could still fall victim to fissure 8’s molten rock.
“It would depend on how much lava is stored in the interior of the flow,” he said.
“Lava like this has a tendency, when it comes out, to flow along the coast instead of go straight into the water. And so, what you see there is a lobe of lava that’s following the coast towards Pohoiki. There’s no way to tell right now whether that will continue or whether it will die off.”
Noting that today is the first day of instruction for the 2018-19 public school year, Kim said plans are still a go for a bypass road for the damaged section of Highway 11 between the 28- and 32-mile markers in the Volcano village and Hawaii Volcanoes National Park area.
“It’s full speed ahead on all the planning mechanisms we’ve got going, including meeting with the governor. … All of that will continue,” he said. “What we’ll do now is re-evaluate when we’re going to start. The plans to expedite this still remains until (scientists) tell me this is over. … The initial plan for completing the temporary emergency highway was two weeks. Hopefully, now, we’ll have a little breathing time to slow down a little bit.”
Hawaii Volcanoes National Park remains closed for the time being, as well.
According to Neal, despite the reduced intensity of both summit seismicity and lava production, HVO is “trying to reinforce the message that the hazard has not gone away.”
“There’s still active lava in the channel; there’s still lava going into the ocean. So we’ve got laze and the attendant hazards from that,” she said. “There’s still (sulfur dioxide) coming out of the fissure 8 vent and the other cracks nearby. So we don’t want people to just completely let down their guard and think it’s safe. They still need to pay attention to Civil Defense closures and that sort of thing.
“Likewise, up at the summit, even though things are quiet, we’ve got all these steep rock walls that have developed during the collapse events, so it’s possible that rock falls could occur on their own. It hasn’t become a completely safe environment.”
Email John Burnett at firstname.lastname@example.org.