BillTre said:
1) different volcanos have separate plumbing systems for thee magma, if one part is draining to another part, they are of the same volcano.
1)
yes, and that is what is happening here. The magma is moving eastwards through the rift system, the result of which is that magma is draining from the main caldera of Kilauea
The vents/feed system of the eastern area of the island ( the Kilauea volcano) is quite complex. It isn't the ummm, "reasonably typical" one or 2 feed tubes branching off from the magma chamber. This is because of all the rifting that is giving magma many, many possible paths with which to push through on the way to the surface.
BillTre said:
2) Different volcanos would seem to be spatially separate from each other at the level of their hot magma load coming up from the mantle as separate events (but probably with a larger more distant common source, like a hot plume).
2) Don't forget that the Hawai'ian Is. chain and hotspot spot is reasonably unique. It is one of only a tiny number of hotspot volcanoes that can be easily observed on land. 99% of them are under sea in various places around the world.
The majority of land based volcanoes seen around the world are the result of subduction zone tectonics and mantle plumes and the like are not a factor.
The magma isn't coming up from the mantle, rather it is a melt produced from the mix of subducting oceanic floor and continental crust. This is why these type of volcanoes are more explosive than the Hawai'ian ones.
BillTre said:
3) In Kilauea (see map,
from here), magma can flow under ground through cracks (perhaps areas of weakness) of some kind (very linear on the map), before coming up to the surface. I guess these would be close to the surface.
3) Yes, they do come up close to the surface. In one of those links above, can't remember which, there are comments that the rifting and fissures also go very deep.
The rifting and fissures really do aid in the propagation of magma into other areas.
From what I have read and understand, there is much more rifting associated with the eastern side of the Big Island that on the other side.
And that leads to one of the big concerns for the SE side of the island of a flank collapse along the Eastern Rift sections on the SE side of the Kilauea Volcano.
here's some interesting stuff …..
https://hilo.hawaii.edu/~kenhon/GEOL205/Flank/default.htm
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2007JB005124
BillTre said:
I wouldn't call these lava tubes (issue with relatives) because they are pre-made in the ground rather than a solidified surface of a flow of lava, but maybe I'm wrong.
Correct, lava tubes are a very specific thing and are formed from the flow of lava/magma. The last time I was in Hawai'i, my mate from Kona took me to a big lava tube NW of Kona. It is accessible from the side of the road and isn't overly old. was formed during one of the last lava flows from the Hulalai Volcano.
A lot of the tube was around 3 - 4 metres in diameter … I'm almost 2 metres tall (6'4") so I could walk through much of it without ducking my head.
BillTre said:
What about possible
Manipulations:
1935 Bombing of lava tubes to expose a flow to greater cooling is
claimed to have saved Hilo.
However,
its effectiveness has been disputed.
1) Would that be legal in HI these days?
2) I could see some other possible purposes:
- Trying to direct a surface flow; like making a trench for it flow in, or making a berm.
- Trying to greatly increase flow out at one place to alleviate pressure on the whole system in a controlled manner, say at a location where the flow would go right into the ocean (the blue lines in the map above are the lines of greatest fall, paths surface lava should like to follow).
- Trying to create fractures (fracking or putting bombs down drilled holes) to direct the underground flows).
Do people do any of these, these days?
1) Would that be legal in HI these days? …. probably not , imagine the public uproar. Apart from that, would you want to take responsibility if the activity caused a huge increase in volcanic activity ? Considering the flank instability of the Eastern Rift Zone,
it could induce a major disaster.
BillTre said:
Do people do any of these these days?
I know of only two cases where active efforts were done to divert lava flows...
1) In the Iceland Island of Heimaey, 1973
https://pubs.usgs.gov/of/1997/of97-724/methods.html
2) On Mt Etna, Sicily, the use of huge concrete blocks dropped from helicopters to divert the flows.Dave
. If something does happen while I'm there, If possible, I'll post an update. But it will likely be brief. I don't have an unlimited data plan on my phone, and unfortunately my hotel in Kona doesn't have free wi-fi ( and I'm not paying for it).
