Pu‘u ‘O‘o was like the kvetchiest relative imaginable: It vented more or less nonstop for 35 years — a staggeringly long time for an eruption — until it suddenly collapsed on April 30 last year, according to the U.S. Geological Survey’s Hawaiian Volcano Observatory. It was old, its pipes were shot, its gaskets blown, its magma tap run dry.

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“The plumbing system catastrophically failed,” the observatory said in a Jan. 31 bulletin. Volcanologists had delayed their pronouncement several months, until they were satisfied that Pu‘u ‘O‘o, 12 miles from the summit of one of the most active volcanoes on Earth, was really and truly done. “It is extremely unlikely that lava will resume activity within Pu‘u ‘O‘o,” the bulletin said.

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Pu‘u ‘O‘o was like the Rolling Stones of eruptions, starting up at 12:31 a.m. on Jan. 3, 1983, running hot and never never never stopping, until at last it did. Except for minor pauses of a few hours or, occasionally, days, it kept going, serving lava in two varieties, syrupy pahoehoe and crinkly-crumbly a‘a, along with the usual sides of gas and ash and earthquakes. It was, in the appreciative gushing of geologists, most voluminous.

Pu‘u ‘O‘o kept an entire generation of scientists at work, along with tour operators, civil defense officials and — for a big, lava-spattered chunk of 2018, when Kilauea became unusually, spectacularly destructive — mainland news crews.

Over the decades, the vent threw up fountains and curtains of molten orange. It spat lava bombs and cast smoke and “vog” — volcanic smog — across the Hawaiian island chain. What it didn’t burn, it buried: Kalapana village, with its lovely black-sand beach and historic grove of coconut trees; a Protestant church; and an ancient Hawaiian temple, Waha‘ula, built in the 13th century. It would have also taken a little wooden Catholic church, Star of the Sea, except parishioners loaded it on a flatbed truck and hauled it a mile and a half away.

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Hundreds of homes were lost in the most lava-prone zones, subdivisions with aspirational names like Royal Gardens and Leilani Estates. Many news articles were written about the displaced, and a few about the lucky, like Jack Thompson, a guy who turned his lavabound house into a B&B, a motorcycle ride across the pillowy blackness. Reporters loved the story of the most isolated vacation rental anywhere, until it was buried, too.

But Pu‘u ‘O‘o also inspired and taught and dazzled and confounded volcano scientists, who felt lucky to be alive at that time, in that place, with an eruption that was always on.

On an island that is a patchwork of slumbering volcanoes, Kilauea is restless. But even by 2003, Pu‘u ‘O‘o was notable for being the longest and most reliable Kilauea rift-zone eruption in 600 years. Scientists with their puny life spans are like fruit flies to volcanoes, which can happily idle in executive time for 200 to 500 to 1,000 years. The chances of being alive and on the job when something this volcanically spectacular happens are not great, Pu‘u ‘O‘o notwithstanding.

In the mid-1990s, when the Pu‘u ‘O‘o eruption was barely a decade old, it was possible to drive the whole ropy length of Chain of Craters Road in Hawaii Volcanoes National Park, from the summit down to sea level, and park near the edge of an active flow. Park rangers stood by to answer questions and move traffic cones to keep the crowds safe. With some agility and reasonable tourist-level daring, you could go right up to the flow and watch the birth of earth: fresh hot rock delivered from the mantle to within a yard of your suddenly alarmingly thin sneakers.

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When I was there, the heat off the pahoehoe was like a physical barrier. You could indulge your curiosity this much and no more, so hot was the air around the red-and-black ooze. At night, the dull black flow with its smoke and steam was transformed: Now you could see an orange streak lighting up the mountain slope, under an almost-touchable Milky Way.

Around that time, in the same place — the spring of 1995, at the end of Chain of Craters Road — a Yale physics-and-English graduate was pondering where to do her postgraduate study. Kilauea sold her on the spot. Today, Jackie Caplan-Auerbach is a geology professor at Western Washington University, in Bellingham, Wash., a geophysicist and seismologist who credits Pu‘u ‘O‘o with inspiring her career.

“I took one look,” she told me in an interview. “It was so mind-blowing to me that this primal and fundamental activity of the planet was right there to study. It was a life-changing moment.”

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Recently, Caplan-Auerbach wrote a touching Twitter thread, both an obituary for Pu‘u ‘O‘o and a personal reflection:

“I was in high school when the eruption began. In my scientific lifetime, I’ve never known a time that Kilauea was not erupting. It was the background to my scientific career.”

She guessed that this was “true for the majority of today’s volcanologists . . . We have a whole generation of volcano scientists who grew up with this eruption,” she wrote. It “taught us about hot spot volcanism, about volcano seismology, geodesy, petrology, volcanic structure, hazard mitigation, gas geochemistry, and magmatic plumbing.”

“Those of us of the Pu‘u ‘O‘o era were spoiled because it was always erupting,” Caplan-Auerbach told me. “Maybe we each have our touchstone eruptions and earthquakes. For many of us that was Kilauea.”

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The collapse of Pu‘u ‘O‘o wasn’t the absolute end of anything, just the end of one stunningly long eruptive phase on one part of a mountain that still has other pipes to the Earth’s magma supply. Even after April, lava kept flowing downslope of Pu‘u ‘O‘o, into the increasingly lava-layered Puna district. Meanwhile, Kilauea’s summit crater, Halema‘uma‘u, also massively collapsed last summer, amid a surprising barrage of explosions and earthquakes, causing a thousand volcanologists’ jaws to drop. Explaining why that happened, and how all these events were related, will occupy many of them for years to come.

“Leaving us with more questions than answers may be the greatest gift of this eruption,” Caplan-Auerbach wrote on Twitter.

When I reached Don Swanson, a longtime research geologist at the Hawaiian Volcano Observatory who recently published his own meditation on Kilauea’s mysteries, he talked about how challenging and intriguing it is, even when — especially when — it’s not erupting. “If you like stability, and you like to go home at night and think you know everything, this is not the time to be at Kilauea,” he told me.

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Kilauea is pretty quiet now, like its older siblings Mauna Loa, Mauna Kea and Hualalai. The scientists have plenty of time to wait, watch and wonder. They are keeping an eye on Loihi, a slowly growing volcanic island-in-the-making, about 20 miles southeast of Hawaii Island and still about half a mile underwater.

Caplan-Auerbach, who has studied Loihi, says at the rate it’s erupting, it will pierce the ocean surface in 100,000 years, give or take.

Twitter: @LawrenceDownes

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