Janet Babb, Kīlauea Update: Good afternoon, everyone.
On the Lower East Rift Zone, Fissure 8 is still active. It continues to erupt lava into the perched channel that extends down on the west side of Kapoho Crater and feeds lava into the ocean. This morning, the main ocean entry was a little bit west of Ahalanui, with the flow margin about 500 meters, or 0.3 mile, from the Pohoiki boat ramp. There’s still some weak ocean entry points to the north of this main entry over near the Kapoho Bay lobe of lava where there were some weak, wispy plumes there. The flow front along the ocean, along the coast is still about 6 kilometers wide or 3.7 miles wide. On the Lower East Rift Zone, the sulfur dioxide emissions remain high, and the ocean entry hazards include the laze plume, as well as the possible hydrovolcanic explosions, what we referred to on Monday as “littoral explosions.” Hydrovolcanic is a little more intuitive word to explain the lava-seawater interaction.
Up at the summit, as we speak earthquakes are occurring at a rate of about 25-30 per hour as the volcano builds up to the next collapse event [this phonecall at 1 pm, collapse came at 4:33 pm.] The previous collapse event weas at 1:28 am July 18, so it’s been about 36 hours. We are within that time interval where we typically see these collapses occur. At the summit, the sulfur dioxide emissions are low. We’ll be posting some new photos and a new map shortly after this media call. That’s all.
July 19, 2018. USGS: “Volcanic gases rising from the fissure 8 vent and lava channel feed a pyrocumulonimbus cloud above the tephra cone. Small pits in the tephra deposit (foreground) form when the lava fragments collapse into cracks and void spaces below the surface.” (Full-sized)
Today’s Eruption Summary
As per usual. Fissure 8 continues to feed the lava channel down to the ocean, where the southern margin of the flow was 500 m from Isaac Hale Park this morning. Lava levels in the channel this morning were low, with the previous collapse event coming at 1:28 am the day before.
July 19, 2018. USGS: “An aerial view looking south, with the fissure 8 lava channel on the west side of Kapoho Crater, visible at left. As it nears the ocean, the channelized lava transitions to a broad ‘a‘ā flow that spreads laterally and toward the coast. The ocean entry plume is barely visible in the far distance (top).” (Full-sized)
Today’s summit collapse event occurred at 4:33 pm.
July 19, 2018. Collapse event tweeted by USGS: “Hereʻs a photograph from the 4:33PM #TypeA collapse event from #Kilauea summit. Rockfalls occurred from near-vertical cliffs around the #caldera and #Halemaumau.” (Full-sized)
WHT: “Fire sparked during RIMPAC exercises consumes 2,000 acres” – As I suspected. Those fires on the saddle between Mauna Loa and Mauna Kea which prompted the usual “Is Mauna Loa erupting?” questions were started by military training exercises.
Mick Kalber Overflights
Mick posted yesterday’s June 18 overflight (good views, including that lava flow moving over a still-active but slower flow) and notes as well as today’s:
Q: [Is Cape Kumakahi still the easternmost point of the island?] USGS: The area off Kapoho has a paltry supply of lava now – unless significant lava returns, the eastward advancement may cease.
Q: [Has there been any change in temperature of lava, now that it’s crusting over and/or not a fluid channel all the way to the ocean? Any sign eruption is ending?] USGS: No, the temperature remains the same. Other factors are probably responsible for the crusting – blockages, flow velocity, precipitation, etc. Sometimes the channels remain fluid, and sometimes the surface can crust over – but that doesn’t mean there isn’t lava moving beneath the crust… No, no signs that the eruption is ending yet.
July 19, 2018. USGS: “his HVO geologist is standing on tephra (airborne lava fragments, such as Pele’s hair) that was erupted from and deposited downwind of the fissure 8 vent. He was there to observe the vent activity and to capture both thermal and video imagery of the pulsations occurring in the near-vent channel. The frame of a water catchment tank cover can be seen in the tephra deposit to the left of the geologist’s camera and tripod (center).” (Full-sized)
Q: [Someone asking about webcams and livestreams] USGS: We weren’t able to adjust the bandwidth on the cam from HVO, but we did add the stream from the northeast caldera, which uses a different (and still challenged) connection.
July 19, 2018. USGS: “Numerous rockfalls have occurred within Halema‘uma‘u and along Kīlauea’s summit caldera walls today, stirring up existing ash deposits and rock dust, and creating sounds that, at times, could be heard from the northeast rim of the caldera.” (Full-sized)
Q: [Cinder cone is 120 feet now? Was 180; has it collapsed?] USGS: Some settling has occurred, and some of the more precarious bits have probably fallen in or down the slopes. [Same basic question, different day] USGS: Yes it has succumbed to thermal erosion, collapse, and settling. There have been no sustained fountains depositing material on its outer slopes for several weeks, so there has been no additional accumulation of tephra.
Vladimir Vysotsky on FB: USGS Volcanoes: you keep characterizing this as a “perched channel”. I wonder if that is how lava tubes form – a channel builds the foundation and walls around itself, then crusts over while still flowing inside, and eventually forms a tube when the lava finally drains. Is that a correct assumption?
USGS Volcanoes: That is a very accurate description of lava tube formation! ][…] Hereʻs a video from Hawai’i Volcanoes National Park describing what you d[id] with video footage to accompany for visual reference. https://www.nps.gov/media/video/view.htm...
Q: [Is Fissure 8 how Diamond Head formed?] USGS: – Diamond Head is a tuff cone that erupted through water. It is also considered “rejuvenation stage” volcanism. The eruption that formed it occurred after the Koʻolau Volcano (from where it erupted) had been dormant for about 2 million years! http://volcano.oregonstate.edu/post-erosional-rejuvenation
July 19, 2018. USGS: ” An aerial view looking to the west, near the braided section of the fissure 8 lava channel. During this morning’s overflight, the channelized lava was at a lower level than usual, but was still being fed by vigorous outflow from the vent.” (Full-sized)
Q: [How long will this go? How will it end? Does a lava flow normally start slowing down and then stop?] USGS: This could go on for any number of days, honestly. Typically these things don’t just turn off and stay turned off. We expect that activity in Fissure 8 will wane, then stop and start again (perhaps at other fissures). However, the eruption won’t stop all together until the pressure driving the magma out of the ground has been relieved.
Q: [How deep is lava channel?] USGS: We have tried to calculate depths based upon lava-flow observations within the channel and known depths of dormant channels on other locations in the Hawaiian islands. The channel is meters in depth, but likely not more than 10. Depth varies throughout its length as well.
[In discussion that Fissure 8 is not a volcano— it’s a vent on Kilauea’s flank just like Puʻu ʻŌʻō was, with magma being piped down from Kīlauea’s magma storage system— someone brought up Lō‘ihi, which IS a new volcano (or seamount) off SE coast of Big Island, still underwater.]
July 19, 2018. USGS: “As of this morning, the southern margin of the fissure 8 ocean entry was about 500 m (0.3 mi) from the boat ramp at Isaac Hale Park.” (Full-sized)
Q: [Is the summit caldera sitting on the magma chamber?] USGS: The subsidence area within the caldera essentially overlies the area of the shallow magma storage region that fed the lava lake in Halemaʻumaʻu. So, yes. Q: [Could the floor collapse into the chamber? What would happen then?] USGS: Technically speaking, the floor, and everything that was between it and the top of the chamber, is collapsing into it. Youʻre seeing the outcome – pressure drops and collapse events that manifest as M5.3 earthquakes.
Things too obscure to bug USGS about: why is it “littoral” when the Latin word for seashore has only one “t”? [Checks etymology: ah, yes, it’s a Medieval Latin spelling.)
