Kilauea’s summit eruption will become 10 years old Monday and scientists say they don’t expect it to stop anytime soon.
“Overall, the (lava) lake for the past several years has been very steady,” said Matt Patrick, a geologist with the Hawaiian Volcano Observatory, referring to the large pool of molten rock inside Halema‘uma‘u crater. “It’s not showing any signs of diminishing.”
That’s good news for scientists who use the lava lake to take the pulse of the volcano and for the many visitors to Hawaii Volcanoes National Park.
“It’s probably one of the most user-friendly volcanoes on Earth,” said Jessica Ferracane, park spokeswoman.
The eruption has been a boost for park visitation, which increased 58 percent in the past decade, she said. While the lava lake has been a constant presence during that time, it’s not a static feature.
“It’s always different,” Ferracane said, noting the lava lake continues to grow and rise and fall in concert with changes in magma supply. Sometimes the lake itself is visible from the Jaggar overlook, but the ever-present nighttime glow never fails to excite.
Patrick said it’s one of the world’s two largest lava lakes and spans more than 900 feet. He said lava lakes within the crater were the norm for the 19th and early 20th centuries, capturing the awe of visitors such as writer Mark Twain, who commented the sight “fascinated the eye with unapproachable splendor.”
Summit and flank eruptions, such as the one ongoing at Pu‘u ‘O‘o, also have occurred at the same time before. But none have been recorded for this length. In the past, they were observed happening together over days or weeks, not years or a decade.
What gives it its endurance?
Patrick said that might have to do with a surge of magma below the volcano that was observed in the years leading up to the eruption.
“That’s not exactly clear,” he said. “We do know (the summit and Pu‘u ‘O‘o) are jointly fed, both are fed by the summit magma chamber.”
Patrick, who started at HVO about six months before the eruption, said an increase in gas emissions and earthquakes at the summit indicated something was happening in the volcano. But no one knew for sure that an eruption was about to happen.
What caused the confusion was that the volcano actually was deflating, meaning the amount of magma below was decreasing, when the eruption happened.
“In 2008, this vent opened up,” he recalled. “It punched a hole and … opened up a pathway that has been sustained.”
At the time, Patrick said he was mapping lava flows from Pu‘u ‘O‘o, which has been erupting almost continuously since 1983. An ocean entry had just started, already causing a spike in media interest.
“We knew overnight” that something happened, he said. “A staff member was working through the night. … He looked out the window (after an explosion) and the glowing, degassing area seemed to disappear. There seemed to be a new pit.”
After daybreak, geologists drove through a plume up to the now-closed overlook parking lot and heard crunching under their tires.
“They thought maybe they drove off the road,” Patrick said. “But then they kept going slowly and the plume cleared. They could see the road but it was covered in ejectile.”
The lava lake started at 100 feet wide and has continued to grow as rocks crack and fall in, occasionally triggering explosions in gas-rich lava.
It’s also presented geologists with an almost unprecedented view into the heart of the volcano.
“With most volcanoes, lava is deep inside a crater,” Patrick said. “You can’t see what’s going on.
“… The idea is by looking at changes in the lake, you can learn more about changes in the magma chamber.”
He said the lake acts as a “pressure gauge” for the volcano, which proved valuable in 2014 when lava from Pu‘u ‘O‘o was threatening Pahoa.
“One of the key events of the Pahoa crisis was that flow was starting to move through Pahoa and starting to reach Pahoa Village Road,” Patrick said. “It got within 150 yards of the main road and it really looked like if things continued it was going to destroy residences and cover the road.
“But, fortunately, we had big deflation. The lava lake dropped rapidly. The magma supply rate dropped. Within a day or so, that flow front in Pahoa stalled.”
HVO and park officials will mark the anniversary with a Facebook live event at 6:15 a.m. Monday.
Geologists also will be at the Jaggar overlook from 11 a.m.-noon to talk with park visitors.
Email Tom Callis at tcallis@hawaiitribune-herald.com.