This evening's thread explores how the Mauna Loa eruption is like a jelly donut. Stick with us -- we're not scientists but we know our way around a handy metaphor. #MaunaLoa 🧵 (1/9) 
When lava runs down a hill, it acts a lot like water. It seeks the steepest path, and its flow is somewhat predictable. But when it hits a plateau, like the Big Island saddle, things change. They slow down. That's where Mauna Loa is now. (2/9)
That's also why its unclear when the lava might threaten the Daniel K. Inouye Highway; instead of barreling like water down a hillside, the lava is oozing along like... really hot jelly? Sort of. (3/9)
A scientist from the @USGSVolcanoes Hawaiian Volcano Observatory this week noted that the lava lobe in the saddle is a bit like "a big jelly donut." The edges have cooled and firmed, but the lava filling is still being pumped in at something like 100 cubic yards PER SECOND. (4/9)
(It's a big donut.) (5/9)
It has to go somewhere, but "straight downhill" isn't on the menu any more. So it can spread out, which the maps show it's already doing. (6/9)
It also can puff up, supported by the doughy/cooled rock walls around the outside of the "doughnut." We're seeing that, too. The lava at the far end of the lobe is now about 20 feet high. (7/9)
It's also possible that the side of the delicious treat gives way, and jelly/lava goes shooting out in an unexpected direction. It could go west, in which case it might not threaten the highway at all. But there's no way to predict that. (8/9)
If the slow spreading continues until the eruption stops, it might just get wider and deeper -- again the mountain will decide. But just in case, emergency managers in Hawai'i County and statewide are looking at what the consequences would be. And now we want donuts. (9/9)
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