Tuesday, December 13, 2022

Latest eruption wrapping up, it looks like

Well, it was fun while it lasted: over the past few days the indications are that Mauna Loa's latest eruption is coming to an end. It's always possible it could restart, of course, but observations of past eruptions suggest that's pretty unlikely. Interestingly, Kīlauea's latest eruption (which started the day I returned to Hilo last year, September 29th) also seems to have stopped, with the lava lake in its caldera abruptly cooling and solidifying. It's an open question how much influence the two volcanoes have on each other – for instance, historically Mauna Loa has often been active while Kīlauea was quiet, and vice versa, but that's certainly not always true. They're definitely two separate volcanoes with separate magma reservoirs, and go off independently, but their general proximity makes it seem likely that there could be some degree of influence between them. It's possible that magma erupting from Mauna Loa in this eruption relieved pressure on Kīlauea's magma chamber and in some part caused its eruption to end, for instance. But it remains an area of active research for now.

On the mundane side of things, this means Saddle Road is no longer in danger of being overflowed, which, depending on where it happened, could've been very bad news for the observatories on Maunakea (not to mention a very large number of other people who rely on Saddle Road to get across the island). The observatories on Mauna Loa remain cut off, as the flow crossed the Mauna Loa access road very early on in the eruption. It was definitely strange to see photos of it, considering how familiar I am with that road. Assuming that the eruption has indeed stopped at this point, I'm curious to see how long it'll take for the road to be reopened (or rebuilt?) and when I can get up to its end again. Once that happens and the volcano is deemed safe and the summit trails reopened I definitely would like to tackle hiking Mauna Loa's summit again, to see where the fresh lava coated the caldera's floor.

And that brings up the really interesting question: when will the next eruption happen? The thirty-eight year period between the previous eruption and this one was the longest in recorded history for Mauna Loa. Prior to this, it erupted fairly frequently; I've seen five and nine years for its average eruption frequency, so it might depend on how you count, but the point is that it happened pretty often. Of course, there was significant variability among historical eruptions, with multiple eruptions sometime occurring in a single year and a recent twenty-five year quiet period from 1950 to 1975. So who knows? We might be back to seeing eruptions every few years, or it might be decades again before the next one. We'll just have to wait and see! As I've said at least once before on this blog, life's never dull when you live on an active volcano in the middle of the ocean. A hui hou!

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