May 27: First Well Covered; Emergency Evacuations From Fast-Moving Lava

The dramatic light show I noticed on the East Rift Zone webcam last night was probably from fissure 7, featured on today’s Mick Kalber helicopter flyover (warning: noisy).

(Blog post: Mick Kalber’s observations from this flight)

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:

[EDIT] Things got a little TOO exciting this evening, and I kept having to update this post…

Continue reading May 27: First Well Covered; Emergency Evacuations From Fast-Moving Lava

May 27: Lava reaches PGV property

I see from Hawaii NWS that small summit ash explosions continue, probably dusting downwind communities. But events down at Leilani Estates have dominated the news today.

To recap: after much foot dragging and a history of safety violations, Puna Geothermal Venture has not won the confidence of many Puna residents.

But Hawaii Civil Defense also confirms the now-quenched wells are “essentially safe.” The concern is that toxic hydrogen sulfide could be released if lava breaches a geothermal well. PGV worked to secure these wells last week, but they’re flying in 200,000 pounds of clay from California today to contain explosions, so…we’ll see.

#LeilaniEstatesEruption #KilaueaVolcano UPDATE (May 27 at 10:15 AM): Hawaiʻi County Civil Defense agency officials cannot tell me what would trigger a mandatory mass evacuation of the area surrounding Puna Geothermal Venture — despite the fact lava has reached the 40 acres of their operational plant site and is approaching the well field. Civil Defense officials say no wells have been impacted and a team is working to prevent threats from developing. At this time, no hydrogen sulfide has been detected. I asked Civil Defense: “What would trigger a mass mandatory evacuation of the area?” We were sent this response: “If it becomes necessary for public safety. At that point, we will alert the public.” We followed up with these questions: “Can you explain what government officials have determined this threshold to be? It’s obviously not lava inundating PGV property, so can you clarify?” We were told there was no additional information beyond their statement. We have since reached out to the Governor’s office for assistance and have confirmed Gov. David Ige will be returning to Puna this afternoon. At last check at 7:30 AM, PGV spokesperson Mike Kaleikini said the nearest well was about 130 feet away from the lava flow front. “All of the production wells nearest to the lava flow are plugged and shut in. According to HVO scientists, movement is currently stalled. As long as conditions are safe, we will have personnel on site. Primary concern is sulfur dioxide from the eruption and lava coming on site. We monitor for hydrogen sulfide and sulfur dioxide on a continuous basis. There are no hydrogen sulfide emissions from PGV wells,” said Kaleikini. PGV officials maintain they believe they have mitigated the threat of an uncontrolled release of hydrogen sulfide if lava inundates their property and makes contact with their wells. However, PGV officials have conceded they don’t know if hydrogen sulfide is the only possible hazard the community could face if lava interacts with their wells. Stay tuned to @HawaiiNewsNow (Video: Civil Defense)

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UPDATE:  Half hour Press Conference with Gov. David Ige and Tom Travis of Hawaii Emergency Management. The gist: the wells are secure, and they’re being monitored.

Lava covered one well this evening. So far, so good:

Video Clips: Pāhoehoe vs A’a (What’s the Difference?)

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?”

May 26: Lava Turns Towards PGV

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.

Hawaii County photo looking south across Pohoiki Road, geothermal plant bottom left. Photo not timestamped but probably around noon. “Fissures 7 and 21 are feeding an ‘a’ā flow that has advanced to the northeast and this afternoon crossed Pahoa Pohoiki Road onto PGV property, USGS reported.”

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?

Next image on the LERZ webcam.

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:

Continue reading May 26: Lava Turns Towards PGV