Sun. Clouds. Rain. Mist. Warm. Chill. Donʻt get too comfortable. Because if you do, change will inevitably happen. I got comfortable with the format of this blog as seen from the bloggerʻs side. Then, rules and format changed, so I got to learn. Still not sure what to / how to deal with answering Comments, so Iʻll do it here.
One asked a couple days ago, the difference between contraction and deflation. Those terms were/are used in the daily HVO Updates. East Rift Zone contracted. Summit deflated. Like that. I explained that both relate to withdrawal, by eruption or intrusion, of magma, so that ground surfaces change shape. They move. ERZ contraction: I likened magma in the ERZ to a fat sausage horizontally in the ground, parallel, more or less, to the coast. Some of that magma apparently fed the eruption in Halemaʻumaʻu, causing the sausage to shrink, or contract. Sideways. At the summit, motions are up/down. Vertical. Inflate Up, Deflate Down. The magma source(s) down there a mile or two increases in volume like blowing up a balloon when supply increases, then deflates when magma leaves. Perhaps thisʻll make some sense to some of you?
Then a question was: How long does/will it take for a lake of hot pele 630 feet deep to cool? A very L-O-N-G time. Rock is an excellent insulator and increases cooling time. We see Kīlauea Iki with steam issuing from cracks on the floor 60+ years after the 1959 eruption. The mass cools from edges in, so the hottest is in the center. The site of ʻĀloʻi, a lua poho (pit crater) filled and buried in 1969 and 1970 by the Maunaulu eruptions still steams. And we read that when the route of Hwy 132 was bulldozed during work to reopen it, the inside of the flow a few tens of feet down measured 700+ degrees Fahrenheit a year after being emplaced.
A grey start to the day up at Kaluapele...with not a lot of red visible. Hmmmm
With the advent of photographic Digital Elevation Models (DEMs), we are able to measure the current Halemaʻumaʻu crater lava lake features in three dimensions. In the January 2021, the largest island is about 250 m (820 ft) long, 135 m (440 ft) wide, and roughly 20 m (65 ft) tall. On Friday afternoon (Jan 1) the islands’ edges were about 6 m (20 ft) above the lava lake surface. By Monday (Jan 4), the whole island had risen by about 2 m (6-7 ft). Photographs, webcam imagery, and eyewitness observations indicate that it formed through a combination of lava interacting with the lake water, early lava flows, and tephra erupted from the early highest fountains. The island has rotated and moved both eastward and westward since its formation on the first day of the eruption. At 10:30 p.m. HST on January 6, 2021, the island stalled in rotation and movement. The apparent buoyancy changes of the island may be due to a density increase in the lava lake as gases escape or sloughing off of island material from the subsurface.
Always something new to us, but research allows insight to the past...
Below, a thermal image from this morning. The top half of the loko ahi is cooler than the bottom half. And even the bottom half, where the incoming pele arrives at the whiteyellow area, seems less active.
We make observations. And often look at webcams to track changes. And we read the UPDATE:
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