A little article while we happily wait for the USGS to confirm that Kilauea is about to sprout a green caldera lake, or not.
I normally do not write a lot about Kilauea, the reason for this is that it rarely does anything interesting. But, in 2018 it did quite a lot of interesting things, but for various reasons I wrote little publicly about it.
Before we get going on Thursday’s news, let us do a small recap on what happened. At least from a volcanically interesting standpoint, and that means that I will talk about plumbing. Most who read Volcanocafé have noticed that I often write that the edifice is just the erect end-product of the volcano. And that the volcano itself starts where magma is created, in the plumbing that carries the magma upwards.
It is down there in the warm depths that the interesting things happen. To understand a volcano, one must understand its bowel-movements.
Kilauea 2018 eruption
Kilauea had been pretty much in a steady state eruptive phase from the 3rd of January in 1983, when the eruption in Lower Puna started on the 3rd of May 2018.
The most famous parts of the 1983 eruption was the formation of the PuʻuʻŌʻō Cone and the 2008 rebirth of the Halema’uma’u Crater inside the caldera.
For being a medium sized eruption from a large volcano, 1983 was a fairly uneventful eruption, at least from a volcanological standpoint. For the residents it was a horrible event as large areas were devastated, and many lost their houses.
In early 2018 I became somewhat intrigued by the changes in the GPS trajectories on the stations facing seawards of the rift, because it indicated that a more radical change was possible.
I was obviously not the only one noticing this, so I quietly pondered what it might have as a result. As per usual the doom and gloom crowd and the Daily Mail crowed that half the island would slide out into the sea causing a megadeath tsunami.
Instead I focused upon what might cause it, and what the effects would be. I surmised that it was caused by magma pressure increase in the rift system leading towards Puna, and that soon the rate of spread would be higher than the magma influx from depth causing a rapid decrease in pressure. And that we would either see quite a bit of earthquakes, or even a large one.
The reason I believed that, was that I had already seen this happen at both El Hierro and at Holuhraun.
In the end I decided to not write that particular article, something that I have regretted since. During this period our commentator Jesper booked a trip to go and watch his beloved lava lake at Halema’uma’u, so I thought that I should write and tell him that it would most likely flush before he got there. He remained a bit incredulous about it for a few weeks, before nature served a particularly big bowel-movement proving my point.
Even though the flushing of the magma out of Halema’uma’u and PuʻuʻŌʻō was quite dramatic, and the start of the eruption itself was intriguing, many tend to forget the most important part. The part that happened on the 4th of May at 00.33 local time (12.33 PM for the imperially handicapped Americans) in the form of a M6.9 earthquake.
The earthquake caused the Hilina Slump to move 60cm towards the ocean and slightly downwards. The earthquake happened at 5.8km depth in the intersection between volcanic rock and the old ocean crust.
Now, let us return to the bowels. Imagine that your colon became two feet wider all of a sudden, that would have some rather disturbing effects. For a rather long volcanic rift zone, it means that all of a sudden mother nature needs to fill in a dyke that is all of a sudden 60cm wider, and the only way it could do that was to suck in magma since nature abhors a vacuum. In other words, PuʻuʻŌʻō was doomed, and so was the magma reservoir under Halema’uma’u.
At the top of the rift the result was dramatic as it caused rapidly increased tension on the rift, forcing more and larger cracks to open, and the eruption quickly took off with a vengeance destroying parts of the Leilani Estates.
Obviously, the change means that it is far more likely that the next eruption will occur at the rift part, than in the caldera part, or for that matter around the top of the edifice. Rebuilding the destruction of the magma system that used to feed Halema’uma’u will take time.
It will also take quite some time before the systemic pressure is high enough that far up into the system. Especially since the rift is quite likely to break again as pressure goes up. It will though most likely occur higher up on the rift compared to Upper Puna.
Kilauea in the news
The hydrological system of Kilauea has been extensively researched, and that is also true for the area near the caldera. We know that there are aquifers leading to the caldera and the nowadays destroyed magma conduit that used to feed the Halema’uma’u lava lake.
As the caldera floor dropped into the void caused by the rapidly evacuating magma under the lava lake, it caused fresh contact surfaces to form on those aquifers causing a bit of sedate steaming.
Here comes the intriguing part. The general area is extremely hot, so all water should be boiled off for a substantial amount of time, unless of course there is a lot of water gushing forth. The last part is negated by the sedate steaming that we have seen.
This creates a conundrum in regards of the green little lake that is apparently forming at the bottom of the newly formed nested caldera. It should really evaporate faster than it could collect, at least for a few years more than might have happened. Obviously, the lake could be fed by rain, or a combination of rain and aquifer.
I love scientific mysteries, especially those I can’t readily solve. To quote Sherlock Holmes in the interpretation of Banderdick Cuminsnatch (admit it, you too can’t spell his real name); “The Game is Afoot!”.
Another newsworthy little item is that magma is accumulating at the southern end of the caldera at 2km depth. So far it is too little to give hope for the return of a more glowing lake than the green patch of water that we might have now.
Now, time to wait for nice pictures and for the USGS to confirm, or un-confirm the formation of Kōkā’nui’keokeoʻole’nā’honu.
The reason for this interlude from the series about Vatnafjöll is that Andrej has gotten married and started to learn Finnish to understand his computer. Apparently, a fair bit of vodka is involved in the process. In other words, he has installed Ubuntu and is trying to get to grips with how to produce plots on that system.
So, let us give him a week of marital bliss, before we start pestering him for plots of the bowels of Vatnafjöll.