Most of today’s news is about marauding lava flows in the Lower East Rift Zone, but the ESA just posted another satellite radar image of changes at Kilauea’s summit:
Radar from @ESA Sentinel-1 satellite, May 19 @ 6:30 PM HST (left) vs. May 25 @ 6:30 PM HST (right) shows expansion of summit vent. As of May 25, this included westward growth of the vent rim & a subsidiary pit N of Halemaʻumaʻu crater. Vent area now ~90 acres. #KilaueaEruptspic.twitter.com/z2gwcQ63HO
If you’ve followed this blog at all, you’ve come across the terms “pāhoehoe” and “a’a.” They’re Hawaiian words borrowed by volcanologists as technical terms for different types of lava. How can you tell which is which?
When I visited in 1986, the joke was that “a’a” is the noise you make when you walk on it, because it’s prickly, and “pāhoehoe” is the smooth stuff. But that’s oversimplified, and it confused me. Some of the old pāhoehoe flows we hiked on near Mauna Ulu seemed pretty bumpy to me.
Pāhoehoe lava is runny, faster-moving, and often described as “ropey.” It’s pretty obvious when it’s spilling into a crater or running swiftly in a river. Sometimes it has ripple marks. At other times, the leading edge slows down and turns blobby. Here’s an excellent USGS video of a pahoehoe front in night and day, May 24-25:
Pāhoehoe moves forward by inflating lobes of lava with fresh new lava from within.
Then there’s a’a lava: a crumbly, chunky mass of what looks like a heap of rocks and gravel and dirt, except it’s red-hot under the outer skin. It moves like a horizontal landslide in slow motion, bulldozing everything in its path:
It advances mostly by chunks tumbling forward off the front.
A’a is usually quite slow. You can outwalk it. In fact, you’d usually have time to pack a small suitcase if it showed up at the end of your street. Whereas when pāhoehoe flows downhill or becomes “channelized,” making itself a smooth chute, you can’t outrun it:
Both kind of lava make crinkly noises, but I think of a’a as “clinkity clankity” lava, whereas pāhoehoe tends to slither.
So now you’ll know how to explain it the next time someone asks, “What’s the difference between pāhoehoe and a’a?”
Puna residents watch with a sinking feeling of “I told you so” as a ponderous a’a flow crossed Pahoa Pohoiki Road slightly north of the geothermal plant, inching towards it. Officials think they’ve got the wells quenched (I notice they quietly dropped the idea of plugging them), and that they’re safe.
Meanwhile, Fissure 7 is causing trouble in all directions; its lava pond has sent another flow “cascading into Pawaii crater” (6:15pm). Looking at the map, I’m betting that crater is an old vent from a previous fissure eruption just like this one. In addition to fluid/runny pahoehoe flows, some of the longer flows are a’a.
The summit has also been busy today, with three ash explosions reaching the ~10,000 foot height between midnight and dawn, and some reaching “as high as 12-13K‘ [above sea level]” this morning. Reminder: Kilauea is 4009 feet above sea level (asl).
Moving on. I’ve gotten in the habit of checking the Lower East Rift Zone webcam last thing before I post:
USGS webcam of LERZ. Grabbed just before midnight, May 26. Is that a lava flow coming towards the camera?
I do believe it is. Has that lava pond broken loose?
Lava tally as of Saturday morning: 41 houses, 82 structures total. A further 37 homes isolated by lava crossing roads. Lava has covered 3.7 square miles/2372 acres so far.
Here’s the usual roundup of the day’s eruption news, astonishing views, and geeky info by geologists:
Before this, the main thing USGS was using drones for was LIDAR, but today’s Photo & Multimedia entry on HVO’s website provides drone footage for both the summit steam/ash plume and Leilani/Puna lava flows.
This video was filmed on May 21, 2018, with a UAV (unmanned aerial vehicle). Limited UAV flights above the hazardous Kīlauea summit area, which is currently too dangerous for geologists to enter for ground observations, are conducted with permission from the National Park Service. […] At Kīlauea Volcano’s summit, a nearly continuous plume of gas and steam billows out of the Overlook vent and drifts with the wind. Explosions are occurring about two times a day, producing ash that rises to a height of between 8,000 to 10,000 feet above sea level. Small ash emissions occur more frequently. The larger explosions produce ash that is blown downwind, and trace amounts have fallen in nearby communities.
This footage is from an Unmanned Aircraft System (UAS) hovering near fissure 22 during the overnight hours of May 22, 2018, and looking down on the fountaining fissure complex. The view rotates upward (to the south) to track channelized lava as it flows toward the Pacific Ocean, about 3 mi (5 km) away. The ocean entry is in the distance, recognizable by a small plume. The USGS National Unmanned Aircraft Systems Project Office is assisting with remote data collection and mapping of lava flows and hazards…
HVO’s Photo & Multimedia blog also posted impressive Hilo Civil Air Patrol aerial photos of the lava rivers from yesterday, as well as an image of Fissure 22 taking a nap (it’s still going but lower today on Civil Beat’s Livestream) while the fissures west of it (and uprift) that activated yesterday inundated Leilani Estates.
Earlier in the day… welcome to the Leilani Estates Lava lake. (warning: noisy)
The residents are being absolute champs in coping with this. Here’s another video clip of the lava lake with the homeowner whose home is just outside of it. They’re very philosophical, realizing they took a gamble, which is more mature than some of the people criticizing them for taking a chance on a place that hasn’t had an eruption in about 60 years. And they’re helping one another.
Oh, my mistake. It’s a lava pond.
Kilauea message: Fissure 22 lava output has increased a bit over the past several hours and its lava channel to the ocean entry is consequently a little more incandescent. Low-level spatter at fissures 15 and 16. Fissure 13 has a low fountain through its lava pond.
Mick Kalber’s helicopter overflight video today does a great job of showing the “pond,” the fissures headed from there past the geothermal plant, and the lava rivers flowing south from those fissures towards the ocea.
USGS Updates, News Roundup, And More Vivid Videos:
It’s a day by day look at how this has unfolded for the shaken residents of Puna, for the state officials scrambling to address this fast-moving crisis, and for those who are front-row witnesses to the power of nature at its most destructive… and yet beautiful.
Tuesday evening, USGS Volcanologist Steve Brantley gave a presentation in Pahoa High School. A lot of it is fairly simple, recapping the eruption for residents of Puna. I’ve covered most of what he does in previous posts. But there are a few new tidbits.
His takeaway is worth seeing if you don’t read/watch the rest:
…until that balance is reached, or something else changes, we expect magma to continue moving from the summit reservoir into the rift zone and further down into the Lower East Rift Zone. So that suggests that we’re in it for the long haul. We don’t know how long this eruption’s going to last, but for now, it looks like it’s just going to continue.
Not that it really matters which is which, but I like to know what I’m looking at. 22 is sending lava down to the ocean (and the geothermal plant.)
I think the livestream house is on that raised bump to the right of “PGV,” with the camera pointed SE. I guess this map was devised when 20 was having a low spell earlier today.
Mick Kalber’s usual stunning flyover vid including rivers of lava and lava flows meeting the sea:
Okay, now that we know where we are, what’s happening? Good images, clips and news tidbits after the cut. The main story today was concerns about lava encroaching on the PGV geothermal plant, and the hazards it poses. But first…
News media have finally gotten wind of Civil Beat’slivestream. Some have gotten the homeowner’s permission to film broadcasts on the same porch, so you may hear them if you tune in. At other times, the homeowners or friends they’ve let use the house stop by. It’s surreal yet oddly comforting to hear the homey noises of people, a pet parkeet (?), and wild chickens outside while towering, terrifying yet magnificent lava fountains boom and chuff.
As for the big picture, we’re starting to settle into a routine with Kilauea’s ongoing double eruption:
We don’t know if crater has ejected more “ballistics” (flying rocks) since USGS scientists aren’t risking personnel by entering the possible “flying rocks” zone. Right now they’re working from a temporary base of operations in Hilo.
Hawaii Volcanoes National Park remains closed, not only to keep public out of range of flying rocks, but because of earthquake damage to trails and some park structures. These need to be assessed/repaired.
Park Rangers have set up in Hilo Bayfront to educate public about this historic eruption.
Oh look, another hazard from lava entering ocean: WATERSPOUTS.
And even when fissures don’t spout lava, they can still be dangerous:
Mick Kalber’s daily helicopter flyover includes some intense views of the rivers of lava heading into the ocean, and the big complex of fountains— 20? 22? we’re starting to lose track— that have dominated the Lava Livestream With Rooster for the last several days.
The USGS thermal scan is very informative, too: an infrared satellite detects heat sources (the whiter the image, the hotter it is), and USGS then overlays it on a daylight satellite image of same area. Result, accurate map of where the main flows are, even when they crust over so the lava inside is hidden:
Below the cut: a digest of the day’s eruption news, USGS updates (summarized), and striking social media images and video clips like this: