Kīlauea started erupting in December and so far has had 21 episodes of fountaining.
Steven Lundblad, a geology professor at the University of Hawaiʻi at Hilo, explained why the lava fountains have been going on and off.
"So what tends to happen is the pressure builds up below the summit of Kīlauea because there isn’t an outlet. At some point the magma makes it to the surface, and since it has a fair amount of trapped gas in it, it is erupted out in a fairly explosive manner," Lundblad said.
"We’ve had fountains up to 1,000 feet high during some of the episodes. After that gas is kind of released and some of the pressure is released, then the lava comes out and tends to cap over the top, and that cycle restarts."
Lundblad said an eruptive cycle occurs about once a week in a repeating pattern, followed by a cap on the magma chamber, which starts building pressure again.
He said that when Puʻu ʻŌʻō crater at Kīlauea began erupting in 1983, it too had fountaining episodes at its start. Over its 35-year eruption, it settled down into a pattern of running down to the ocean.
The on-off eruption in Halemaʻumaʻu crater is currently paused, as of Wednesday morning. The Hawaiian Volcano Observatory said the next eruptive episode is likely to begin within three to nine days.
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