Here's what might cause the steady exhalations. Think of blobs rising and falling in a lava lamp. Now put those blobs in an underground pipe that feeds the lava lake from a deeply buried magma chamber. Lava moves up and down the pipe — a flow and counterflow similar to a lava lamp, according to a model in a separate study to be published in the same issue of the journal Earth and Planetary Science Letters.
"The physics of what's going on are fairly different, but it's an easy analogy," said Peters, who is co-author on the "lava lamp" study. "Batches of fresh magma come in as blobs, not as a continuous stream."
But just like a real body, this "breathing" comes from a different part of the volcano than its burping eruptions. Erebus erupts when a large gas bubble emerges and bursts in the lake, splattering lava on the surrounding slopes. Some of the volcano's lava bombs are nearly bus-size.
At Erebus, these belches have a different composition than the gases that ebb and flow every 10 minutes, researchers discovered. The investigators think this difference means that the bomb-launching bubbles come from deeper in the volcano.
"It looks like the two behaviors are very decoupled from each other," Peters said. The gas cycling continues even when eruptions suddenly lower the lava lake level, he noted.
Computer modeling of the upper and lower volcanic plumbing will help explain this strange set of behaviors and provide insight into the inner workings of other volcanoes, Peters said.
But there's a hurdle.
"Basically, all the measurable properties of the lava are still up for grabs," Peters said. Even the lava's temperature is only a guess — it's never been directly measured. That's partly because of the risk of death from flying bombs, and partly because the lake is ensconced in a 330-foot-deep (100 m) crater. "The pipe dream is to do what's called volcano fishing, which is instruments dangled from cables into the lake," Peters said.
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