We have lava in the Halema’uma’u vent, says the USGS this morning!
They report witnessing a ’sloshing’ lake of glowing, molten rock 330 feet below the rim of the vent. It is over 150 feet in diameter, which is a pretty good sized lava pond.
Well, actually, the molten material in the pond, which may reach hundreds or even thousands of feet into the depths of the earth, is technically called magma, according to the official USGS definition. Magma is molten rock below the surface of the earth, and lava is molten rock above the surface of the earth. But call it lava or call it magma, this an extremely significant sighting, and it is very exciting to those of us who are waiting for the main event to happen someday. This would seem to say that day just might be getting close.
Official people saw the lake twice Friday from a hovering helicopter they had flown in for exactly that purpose. They had strongly suspected the existence of magma in the vent not far from the surface, but had not been able to see far enough down in the vent from ground level to confirm their suspicions. And I can certainly understand why they did not want to stick their head into that tumultuous plume.
The afternoon flight saw the pond in a lovely roiling boil, with many bubbles welling up and bursting. This is called ‘gas pistoning’, and there is a very fine movie of that kind of action here. It’s hard to grasp how very large the scale of this vent actually is. It’s an impressive 90 to 120 feet across, and the entire surface bubble bursts and explodes at the same time. Our vent is almost a third larger.
All this goes a long way in explaining why the vent has been enlarging.
Very hot gas… which we have been seeing for days as the rhythmic flares at night and the flash ash clouds during daylight hours… blasts rock from the walls of the vent, along with carrying small amounts of magma up above the surface as lava… the lava that our brave USGS team has been gathering as volcanic glass each day from around the mouth of the vent and several hundred feet beyond, as well as the 3-inch ‘lava bomb’ that landed a couple of days ago in a USGS rain gauge about a thousand feet from the vent.
Kilauea summit has been inflating since about 4AM September 3. We continue with episodes of seismic tremor, which is becoming almost periodic. There have been more hybrid earthquakes/explosions. 17 locatable earthquakes beneath Kilauea, with 12 of those under Halema’uma’u. Surface flow in the East Rift Zone is minimal, although there is still significant outgassing occurring, indicating a significant amount of pressure in the Kilauea system.
We all await upcoming events.
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2 Responses
Larry
07|Sep|2008 1Doesn’t the increased size of the vent make it less likely that we’ll get a dramatic “game changing” event? Bigger vent = less pressure = less instability? I think today’s eruption report said ~1100 tons from Halema’uma’u yesterday, so the bigger vent is apparently still generating enough crud to vog up Kona.
Kona Coffee Admin
10|Sep|2008 2Well, it certainly makes sense that if enough pressure were relieved, there would be no large explosive event. And at this point in time, I would be very happy if the entire event just passed into history and we got our blue skies back.
But I think the history of the activity at Halema’uma’u indicates that the more that occurs… the more likely that something bigger will occur. The enlargement of the vent indicates to me that we should expect more to come. As you probably know, there was enough pressure in the system in 1924 to cause Halema’uma’u to explode extremely violently, throwing multi-ton rocks great distances, and sending a column of ash and gas as large as the entire diameter of Halema’uma’u over 2.3 miles high. The 1790 event was even larger, with extremely destructive pyroclastic flows. The current vent is only about 150 feet in diameter.
You might want to take a look at the post of May 5 which references a pretty interesting account of the very large May 18, 1924 event at Halema’uma’u by USGS, which in my opinion is some of their very finest work.
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