May 19 – Another Ash Explosion Last Night

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.

From KITV May 19:

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 18: “Fresher, Hotter” Magma Arrives, HUGE Fountains Begin

Thursday May 18: Fissure eruptions went into overdrive [Good article from Star-Advertiser] as “fresher, hotter magma” (Janet Babb, USGS geologist) arrived from summit. Fissure 20 released a lava flow down toward coast, crossed Pohoiki Road, and isolated about 40 houses. Four cut-off residents were airlifted out.

Here’s an archived livestream by Honolulu Civil Beat starting before dawn Friday morning:

Check out daylight screencap from late in the broadcast to get sense of scale: note house.

The USGS also posted a brief video clip of Fissure 17 in its Kilauea-Iki-like glory:

May 19, Friday afternoon, a new livestream started from same channel  as before (civilbeat.org). They streamed through most of the night, occasionally shifting view from large fountain behind house (Fissure 17) to lava flow and a group of lava fountains building spatter ramparts (Fissure 20 merged with others) upslope to the right.

Friday, HawaiiNewsNow’s Milika Lincoln filmed same area in late morning from nearby location, near Lanipuni Gardens: fissure 17 fountain was now 500 feet tall. There seems to be a crater (pu’u) forming to the right of 17’s fountain. She also interviewed a resident who saw Fissure 17 form— as they talk, it roars. After dark, her crew’s footage is absolutely spectacular. (She’s calling it 19— either I’m mistaken about which one she’s watching, or she is.)

You can really tell this is hotter, fresher, more voluminous lava that drained from Pu’u O’o, as opposed to the old, stiffer, cooler lava that erupted from fissures in Leilani Estates the first two weeks of this eruption.

“Ground deformation is continuing with increased seismicity” in Lower East Rift Zone, and USGS warn lava inundation below them is possible, and that more fissures could still open uprift or downrift. “All fissures are actively spattering or actively degassing.” 40 structures lost.

May 17, Early Morning: Steam Explosion!

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).

By morning, things had settled down:

Continue reading May 17, Early Morning: Steam Explosion!

About the 1790 Kilauea Eruption

Here’s a summary and primary sources collected by HVO geologist Don Swanson on a 1790 explosive episode of Kilauea.

Also see USGS factsheet, “Explosive Eruptions at Kilauea, Hawai’i?” compiled prior to the 2018 eruptions. Diagram from this page:

3-part diagram: at left, a full lava lake with a long chimney of magma supplying it from below; in the middle is the same lava lake with the lava level dropping way down the chimney, below the water table, so that the upper walls of the chimney are cool enough for groundwater to seep in. Rocks falling from the chimney's walls are starting to choke it. The third and last phase of the diagram shows that groundwater has heated to steam and built up pressure below the rockfall until it builds up enough steam to shoot the blockage straight up out of the chimney.
USGS Diagram Explaining Cause of Steam Eruptions

The factsheet notes that “Many of Kilauea’s pre-1924 explosive eruptions that produced significant ash deposits probably happened when the volcano’s summit crater was so deep that its floor was below the water table, letting ground water seep in to form a lake.”

If I’m understanding correctly, they’re saying that bigger explosions may happen when there’s a lake of water, i.e. more fuel to create steam.

Edited to add: HVO’s page outlining the history of Kilauea Caldera also goes into past explosive episodes. Final paragraph:

“Having pieced together the recent geologic past of Kīlauea, scientists conclude that the volcano will eventually return to a long period of mostly explosive activity, just as it did around 1500 CE. This future explosive period will probably accompany a significant decrease in the magma supply rate and be initiated by collapse of a new caldera to the depth of the water table, which today is about 615 m (2015 ft) below the present high point on the caldera rim. For now, effusive eruptions dominate Kīlauea.”

Note: that’s a new caldera, the much larger basin containing Halema’uma’u crater within it, and the vent that’s erupting ash explosions right now was a small lava lake covering only part of the floor of Halema’uma’u. Orders of magnitude different in terms of size. Also, changing the location of the active vent doesn’t mean the magma supply inside is dropping.

May 16: Summit Ash and Small “Ballistics”

May 16, 8:36 AM, a 4.2 earthquake shook rocks from Halema’uma’u Overlook Crater’s walls that fell into the lava lake, caused an explosion, and sent (according to the USGS)  “dense ballistic blocks up to 60 cm (2 feet) across were found in the parking lot a few hundred yards from Halemaumau.”

USGS photo of “ballistic rocks” found in parking lot next to Halema’uma’u Crater, INSIDE Kilauea Caldera, morning of May 16

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 16: HVO Raises Aviation Color Code to Red

Media freaked out overnight when Hawaii Volcanoes Observatory issued a code red alert following a 12,000 foot tall ash explosion at the summit. The next morning they clarified:

USGS Volcanologist Michelle Coombs (EXCERPT):

So we’ve had some questions about what code red means. It sounds a little bit alarming, It’s really just to say that we see significant amounts of ash from this ongoing activity, and to warn aviators about that ash. It doesn’t mean that a really big eruption is imminent. it’s really just characterizing the aviation situation.

 

May 15: Still Not the Big One

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.”

USGS Geologist @DrJanineKrippner has been playing whack-a-mole on Twitter rumors and addressed “Kilauea’s Alert Level Was Just Raised To Red – But What Does That Actually Mean?” on IFLScience, reiterating that it was mostly an aviation alert. So did volcanologist Erik Klemetti, with a good writeup of today’s steam explosions and fissure activity on his Rocky Planet blog.

May 13: Fissure 17 Starts

I’ve not covered every single fissure: see the HVO Photo/Multimedia blog, the HVO timeline, KITV, and HawaiiNewsNow for fissure-by-fissure coverage, not to mention HNN reporter Milika Lincoln’s Instagram vids and photos, and Mike Kalbers’ wonderful daily flyovers.

Activity ebbed and flowed, some days with more steam, some with more spatter. For the most part, lava flows didn’t go very far, and were largely sticky, clumpy, clanky a’a. But I bookmarked fissure 17 early on for particularly dramatic fountains (those blocks it’s hurling are called “lava bombs”) and incredible booms and roars:

#LeilaniEstatesEruption LATEST (May 15 at 8:30 AM): Incredible new sunrise footage captures the sounds and sight of lava fountains and gas bombs erupting from the 17th fissure — which broke out Saturday off of Halekamahina Loop Road northeast of Lanipuna Gardens on the Kalapana side of Highway 132. According to USGS HVO scientists, fissure 17 has created a narrow lava flow heading makai — or downslope toward the ocean — and has already covered about two miles. Civil Defense officials say based on their last measurement, this flow front is now a little less than a mile from Highway 137. At one point yesterday, it was moving at a rate of about 100 yards an hour, but it has since slowed a bit. The flow has been running roughly parallel to Highway 132 or Pahoa Kapoho Road. Officials say it's heading east in the direction of Kapoho toward Highway 137 — also called Old Government Beach Road, or more commonly referred to by residents as Waa Waa Road. This fissure has already claimed one structure — but officials say there are currently no homes or buildings in its current path. This has been the longest-lasting, most active fissure of the 20 that have opened up since this the first on May 3 along Mohala Street within #LeilaniEstates. Stay tuned to @HawaiiNewsNow for the very latest developments #HInews #HawaiiNews #HNN #HawaiiNewsNow #WeAreYourSource (Video: @bradah.dom / @ikaikamarzo)

A post shared by Mileka Lincoln (@milekalincoln) on

and it was the first one that really seemed to be making a run for the ocean and creating a sustained lava flow.

Here’s May 13 and 14th flyovers from Mick Kalber:

Luckily, it chose a route that doesn’t have many houses downslope. And unlike other fissures, it just kept going and going.

And (since I’m posting this backdated): it’s still going on May 19, after making quite an impressive lava fountain and cinder cone for itself over the past two nights.

May 9-10: USGS Warns of Possible Steam Explosions

Attention shifted back to the summit on May 9, when a 3.1 earthquake set off a rockfall that agitated the lava lake and sent up a 6000-foot poof of ash (video clip National Parks site):

Rockfall into Halema’uma’u lava lake sends up plume of ash, 8:27 May 9.

Rockfalls caused poofs of ash like this even back when the lava lake was full, but that was more than usual. (See also USGS video from May 7, when lava lake was still visible, showing how falling rocks agitate it).

However, that was just a teaser. The big news was the dropping lava lake…

…prompted HVO to issue its first warning about steam explosions if the lava dropped below the water table.

Hawaii Volcanoes National Park closed Friday May 11 as a precaution, since the lava lake was projected to reach the water table sometime that day. For the next few days it continued to send up a white plume of steam and/or ash clouds when rocks from the sides of the chimney fell in:

[USGS] May 11, 9:12 AM: second ash explosion
On steam (phreatic) explosions:

Continue reading May 9-10: USGS Warns of Possible Steam Explosions