Lava fountaining could soon be returning to the Big Island. The U.S. Geological Survey said pressure is once again building up inside the Halemauʻmaʻu crater.
The on-again, off-again eruption at Kīlauea has shot lava up to 1,250 feet just about every week for the past seven months. That's nearly three times the height of the tallest building in Honolulu.
"It's so much bigger and brighter than I sort of ever would have expected, like a reverse waterfall of fire," said Aaron Dill, who was among the thousands of visitors drawn to the summit to witness the 28th episode last week.
This is the sixth summit eruption in the last five years, but USGS geologist Mike Zoeller said this one is unique.
"In many of the other eruptions that I've witnessed since I've been here, the most dramatic phase is right at the beginning, but this one has actually built with higher and higher fountains during the course of it, and we think the reason for that is that the nozzle at the eruptive vent is constricting itself very slightly with each episode," he said.
Zoeller explained it’s like when you put your finger on the end of a hose.
"If you narrow up the exit, then the velocity increases, and it shoots the material even higher," he said.
Each eruptive episode has produced about 1.6 billion gallons of lava — enough to pave a two-lane highway from San Francisco to New York City.
Since last December, more than 31 billion gallons of magma have flowed, raising the crater floor by about 200 feet in some areas.
The eruption is also changing the landscape outside of the crater — adding tephra, fragments of volcanic rock.
“We've got that tephra hill, or a new puʻu forming on the downwind side of the eruptive vents on the rim of Halemaʻumaʻu crater. And additionally, even farther downwind into the Kaʻū Desert ... there's a pretty significant and visible to the naked eye blanket of tephra," Zoeller said.
Fountaining episodes have lasted up to 12 hours before coming to an abrupt stop. But each time, magma has continued to move from the hotspot.
“That movement of magma towards the surface is causing this repressurizaiton in the shallow magma chamber, and then once it reaches some critical threshold, and we donʻt fully understand what that critical threshold is, but it seems to pretty consistent throughout this eruption because once it reaches a certain level on our graphs, very shortly after that we start deflating and lava fountaining once again," he said.
Another unknown is how long this pattern will continue. But based on the data Zoeller has seen, he said it could go on for a long time.
“That being said, it would probably be surprising if this lasted for many, many years," he said.
For now, onlookers continue to be inspired by the eruption, including Aaron Dill's 17-year-old daughter, Juniper Honeycutt-Dill.
"I have always really enjoyed science, and I've never quite known what I wanted to get into, and this makes me want to be a volcanologist," Juniper said.
Check the Hawaiʻi Volcanoes National Park website for the latest visitor information and the Hawaiian Volcano Observatory website for eruption information.
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