On Friday August 19, HVO lowered ground alert levels, just as they lowered aviation alert levels after the ash explosions stopped. Here’s the official notice:
In light of the reduced eruptive activity at Kīlauea Volcano over the last several days, HVO is lowering the Alert Level for ground based hazards from WARNING to WATCH. This change indicates that the hazards posed by crater collapse events (at the Kīlauea summit) and lava flows (Lower East Rift Zone; LERZ) are diminished. However, the change does not mean with absolute certainty that the LERZ eruption or summit collapses are over. It remains possible that eruption and collapse activity could resume.
Remarks: Background and Prognosis
Kīlauea Volcano has remained quiet for well over a week now, with no collapse events at the summit since August 2. Except for a small, crusted-over pond of lava deep inside the fissure 8 cone and a few scattered ocean entries, lava ceased flowing in the LERZ channel on August 6. Sulfur dioxide (SO2) emissions rates at the summit and LERZ are also drastically reduced (the combined rate is lower than at any time since late 2007).
It remains too soon to tell if this diminished activity represents a temporary lull or the end of the LERZ lava flows and/or summit collapses. In 1955, similar pauses of 5 and 16 days occurred during an 88-day-long LERZ eruption. During the Mauna Ulu eruption (1969-1974), a 3.5 month pause occurred in late 1971.
HVO will continue to record detailed visual observations and scrutinize incoming seismic, deformation, and gas data, looking for evidence of significant movement of magma or pressurization as would be expected if the system was building toward renewed activity.
Also on Friday, the National Park Service issued a media release and gave select local media a guided tour of the summit. Lots of info, and worth seeing:
So it’s finally arrived, the end (or at least intermission) of Fissure 8’s endless outpouring of lava from May 27 to August 4. The shutdown happened at the end of last week over a period of just 2-3 days.
Fissure 8 isn’t quite dead. There’s lava pooled deep down the cone, bubbling weakly. Residual lava is still draining out of the lava delta into the ocean, some of it quite near the now-famous Pohoiki Boat Ramp. But most of the surface channels have drained and solidified.
The volcano’s summit has settled, too. The caldera floor isn’t inflating or deflating, and the swarms of earthquakes and summit collapses have stopped.
So now the question becomes: how long do geologists, national park staff and residents wait before deciding it’s safe to start repairing the damage? Past Lower East Rift Zone eruptions have paused for days, even weeks. So scientists and officials continue to warn that this eruption could resume at any time.
This week’s Volcano Watch column from Hawaiian Volcano Observatory, written August 9, addresses exactly that question:
89 days. That’s how long it’s been since the first fissure started spattering lava in Leilani Estates. Which is one day longer than the 1955 Kapoho eruption, which had been the longest LERZ eruption since records started being kept.
Today’s Eruption Summary
LERZ erupton as per usual. There’s “ooze-outs” of lava on the flow margin, but further inland from Pohoiki. Today’s M5.3 summit collapse was at 7:59 am, when the crater was steaming in the cool morning air.
From HVO, the livestream caught the pressure wave passing through the cloud:
From the NE Caldera Rim livestream, ground shaking and rockfalls were more visible:
The LERZ continues as usual, although there are tantalizing hints that change could be on the way:
Fissure 8 gushes within its large cone, Fissure 22 continues to spatter weakly. The open lava channel from Fissure 8 now ends about 2km (1.2 mi) from the coast:
From the end of the channel, the lava dives under the crust of the slightly older flows that buried Kapoho Bay. It emerges again along a very broad ocean entry:
According to USGS/HVO, the ocean entry is “primarily along the northern section,” as it has been for the past few weeks. However, to judge by today’s @hotseasthawaii overflight, there’s notable ocean entries to the south as well. Besides the lava that reaches the ocean, USGS reported lava “oozing out” to the north and southwest of the main a’a field just inland, as one can see on Friday’s thermal map. A few Kapoho Beach Lots houses are hanging on, threatened by the northern “ooze-out.” The southwestern “ooze-out” — several local photographers have reported an unconfirmed “southern lobe” lava flow— is within a few hundred yards of Ahalanai Warm Pond and Kua O Ka La Charter School:
Screencap from early morning July 8 HotseatHawaii overflight. Ahalanui Warm Pond is just at the end of that straight stretch of Hwy 137, and the school is the light-colored patch just to the right of it. (Full-sized)
The Lower East Rift Zone eruption continues pretty much as usual: Fissure 8 feeding a lava river with occasional short-lived overflows. The main lava channel no longer reaches the ocean, but crusts over a half mile from shore and dives into the lava delta, oozing out at multiple points on the northern side. One especially large “ooze-out” makes a short flow on the north side of the flow field near the last few Kapoho Beach Lot Houses, a few of which are hanging on. Fissure 22 is weakly spattering with a weak flow to its east. Today’s summit explosion occurred at 6:04pm, equivalent of M5.3. Thick fog obscured the livestream view.
So that’s all routine, if a volcanic eruption can ever be routine. The big news today actually took place last night (see what happens when I finish my posts early?):
July 5 Volcano Community Meeting
Thursday evening, there was an important community meeting in Volcano Village. Mayor Harry Kim, the USGS and Civil Defense outlined the extremely unlikely but potentially life-threatening (to people near the summit) possibility of large-scale caldera collapse. I’ve transcribed the meeting here. BigIslandVideoNews excerpted the crucial 4-minute presentation from HVO’s Tina Neal:
During the Q&A session, a resident asked about the odds for the worst-case scenario, a large-scale caldera collapse with explosive activity. Harry Kim took the mike from Tina Neal and said, “Like you, we always like to know percentage odds. And she knows; I asked her that. And I’d like to answer because she said, ‘One percent.'” [Tina went on to explain how they arrive at such probabilities; she wasn’t being flippant.]
Another reassuring quote from the Q&A session:
Don Swanson: “I think that the evidence we have today looks to me as if [the subsidence/collapse] is going to be confined to within the caldera, because the outermost circumferential fractures that have been occurring on the caldera floor have not extended outward in the last 2-3 weeks or so. So to me, that suggests that they may be defining the outermost limit of potential caldera collapse.”
The new news today is that HVO/USGS downgraded Kilauea’s FAA warning level:
“Since late May, these collapse/explosion events have rarely produced significant ash plumes rising more than 10,000 feet above sea level where they can pose a significant hazard to aviation. For this reason, HVO is reducing the aviation color code from RED to ORANGE.”
I almost feel like the recent code downgrades for Kilauea and Mauna Loa were a tacit rebuttal of the scaremongers trying to conjure an island-wide catastrophe out of hot air. But I suppose I’m being as irrational as they are. There were specific numbers and criteria for both these status changes.
Down at the LERZ, status quo continues. Fissure 8’s lava fountains are vigorous but seldom peep over the cone they’ve built (now 180′). Minor overflows spill out near the head of the lava river without going far. The ocean entry is concentrated mostly at the main lava channel channel near the south end of the lava delta, but some fans out along a 1km stretch.
Today’s collapse explosion went off at 4:12pm, M5.3, partly hidden on the livestream by a dust cloud from rockfalls 4 minutes earlier. Just as yesterday, I noticed the “collapse explosion” started with a visible camera shake, unlike earlier rockfalls that made me think, “Waaaaait— was that it?” The explosion itself didn’t send up much dust past the rim of Halema’uma’u. About a minute later, dust from caldera wall rockfalls (I think?) blew past.
Below: Rockfalls, dust cloud, then I fast forwarded to the collapse explosion.
Today’s USGS Kilauea update gave additional details for yesterday’s explosion which probably apply to today’s as well: “Seismicity dropped abruptly from a high of 25-30 earthquakes per hour (many in the magnitude 2-3 range) prior to the collapse explosion down to 10 or less earthquakes per hour afterwards. Within 4 hours seismicity began to creep up again averaging about 25 earthquakes per hour by daybreak (June 24)” i.e. about 14 hours later.
Fissure 8 continues as usual, sending its lava river down to the ocean at Kapoho, with a “dominant ocean entry on the south edge of the flow front…producing a large laze plume.” Minor, brief overflows upstream aren’t traveling past previous lava flows. Fissure 6 is inactive; 16 incandescent; 22 woke up and was fountaining weakly during the USGS morning overflight.
I spent this afternoon putting together a gif of the last 28 days of HVO wide angle Kilauea images, using screencaps I’ve taken supplemented with screengrabs from the same webcam archived by Hawaii247:
In today’s digest:
Video capture of today’s summit explosion (warning: dark)
Update: Status quo at Fissure 8, LERZ, Summit. New “tidbit”: front of lava is sitting on ocean floor that was 60 meters deep. Also, using term “collapse explosion” for daily explosions, because not 100% clear whether explosion triggers collapse or vice versa. Tradewinds and showers through weekend.
Questions & answers:
Q: Possibility of new fissures opening, or if not, why not? Has seismicity in LERZ decreased? A: Not ruling it out, but magma has found a good conduit to Fissure 8, seems stable. Seismicity in LERZ “pretty quiet.”
Leslie Gordon, USGS Public Affairs: That will not affect what we’re doing here at Kilauea. I think the department realizes that this is an urgent situation. We have people’s livelihoods endangered. People have lost their homes and businesses. And so we— it will not affect what we’re doing here regarding Kilauea Volcano.
3. Q: Do you think it’s safe local residents to view lava if they’re outside mandatory evacuation zone? A: Not our call. It’s up to Hawaii County.
4. Q: What’s process for naming fissure 8? A: Hawaiian elders, community, Board on Geographic Names decide when and what to call places in Hawaii.
5. Q: Will delta collapse? How far out? A: Can’t rule out collapse, but it’s on fairly stable slope so far; 100-200 meters from where it is now the slope steepens. [Didn’t say what would happen there, but I think implication is that it will be less stable and more collapse-prone.]