A relatively clear day, May 31, finally allowed the USGS to get good, detailed drone footage of changes at the summit.
To orient you on the crater-within-a-crater-within-a-crater (Park Map):
Kilauea Caldera is the megacrater, 2×3 miles across, on whose cliff walls are perched the Hawaiian Volcano Observatory, Kilauea Visitor Center and Volcano House.
Halema’uma’u is a crater on the floor of Kilauea Caldera, about 2500 x 2900 feet. It held a lava lake in the 1800s, but drained and exploded in 1924, after which it was quiet for most of the 20th century.
The Overlook Vent was a crater on the floor of Halema’uma’u containing a lava lake from 2008 until May 2018. It drained and has been exploding with steam and ash since the beginning of May. Rockfalls from its sides have enlarged it:
changes at kilauea’s summit, May 2018
May 5-29, USGS animation using radar data from Italian Space Agency’s Cosmo-SkyMed satellite:
May 23-31, new radar imagery shows more recent changes. The USGS caption notes that not only has the overlook vent widened, but also Halema’uma’u Crater:
Below, a compilation of video footage of Halema’umau and its lava lake in August 2016. Go to timestamp 2:10 for a good view of Halema’uma’u Crater with the Overlook Vent’s lava lake inside. Compare that with the May 31 video above. The black area is lava that overflowed onto the floor of Halema’uma’u when the lake’s level was high.
Note: the “Overlook Vent” was named after the old Halema’uma’u Overlook, because that’s the side where the lava lake vent opened in 2008. There used to be a parking lot and viewing area on Halema’uma’u’s crater rim where visitors could look down into it. In 2008, the Overlook area was closed to visitors, because whenever there was a rockfall into the lake it tended to do THIS:
Hawaii Volcano Observatory Alert: Saturday at 5AM, the summit crater let off a series of explosions at 5AM sending up an ash cloud 11,000 feet that lingered for 25 minutes. Lighter winds may keep ashfall from today’s explosions mostly within the park, giving downwind communities a respite. [Edit: No such luck. Taller ash explosions today had more range.]
HVO webcam caught a nice glimpse of plume by moonlight (“exit” sign of observatory reflected in lens):
Moon illuminates the plume. 3 explosions overnight at Kīlauea Volcano’s summit; ash clouds to 10,000 ft but quickly dispersed. EQs and explosions occur as summit area subsides and adjusts to withdrawal of magma. https://t.co/u8INilHsg0pic.twitter.com/xSgCmXCrhx
USGS reports another explosion last night: “At 11:58 PM Local time, a short-lived explosion at from Halema’uma’u created an ash cloud that reached up to 10,000 ft asl and was carried southwest by the wind. Possible trace ash fall may have occurred along Highway 11.”
I’m not sure whether this was a steam explosion, or just yet another of these rockfall-triggered ashclouds, like this one in 2011:
Hawaii Volcano Observatory is so lucky to have one of the foremost experts in explosive eruptions, Don Swanon, who worked on St Helens so long ago and uncovered Kilauea’s explosive history after transferring to HVO in the 90s.
Experts on this active volcano gathered to share what they know- and what they have discovered is Kilauea has a history of explosive ash eruptions. Hawaiian Volcano Observatory geologist Don Swanson sums, “For the past 2,500 years we’ve had explosions more than 50% of the time, so this is the norm for Kilauea. But most of the explosions are minor, like we saw today, with small plumes of ash and steam rising from the summit.”
May 17, 4:17 AM, the first honest-to-gosh steam explosion like they’ve been predicting (instead of just a rock and lava explosion) sent an ash cloud up 30,000 feet. Gemini Observatory caught it on timelapse:
According to volcanologist Erik Klemetti, the blast threw some 1000-pound blocks, the only place I’ve seen this. See blog post (more pics).
Here they be. They’re ballistic, in that they soar up and down like a cannonball, with the chimney above the lava lake acting sort of like a vertical cannon. But contrary to several headlines I saw, these rocks are not refrigerator-sized.
There is light ash dusting the area and turning it into a moonscape.
May 15, 11:05 AM: A major ash explosion up to 12,000 feet — which HVO still guesses was caused by rockfall into the receding lava lake— prompted HVO to raise the aviation alert level to RED, warning aircraft to stay away from the summit and ash hazards.
Unfortunately, news media took this RED ALERT to be “major eruption imminent,” instead of “no more imminent than it already is, since, as a matter of fact, it’s already erupting. But it could increase activity.”