The Maui News
Friday, June 3, 2002

 

UH geologist predicts that Haleakala will erupt again
Public lecture, hike draw attention to mountain’s movements

By VALERIE MONSON
Staff Writer

HALEAKALA — The morning after they heard that the land they were about to walk on could explode, some intrepid Maui hikers saw the southwest rift zone of Haleakala in a whole new light.

"It appears we’ve been going through a quiet period for the last 300 years, but how long is it going to last?" said University of Hawaii geologist John Sinton. "Is it going to last 1,000 years? Is it going to last 100 years? Is it going to last an hour and a half?"

After listening to Sinton talk about the chances of Haleakala erupting again and then walking with him across a prospective ground zero at Kalepeamoa, the great mountain never seemed more majestic — or enigmatic.
"It might be the longest live volcano in the Hawaiian chain," said Sinton. "It’s been dribbling on for about a million years — 900,000 and still going."


In other words, Haleakala lives. Beneath those sculpted cinder cones of burnt orange and almost purple, things are still brewing. The rift zones that streak up either side of the mountain, from Hana on one side to Keoneoio on the other, make everything along the way vulnerable to an eruption.

Sinton acknowledges that while volcanologists have pushed back the date when they believe the last lava flow occurred at Keoneoio (La Per- ouse Bay) from 1790 to probably between 1450 and the 1600s, those same experts also agree that the mountain has never really stopped pumping.

"We’ve had a major re-evaluation of how we look at things on Maui," said Sinton. "East Maui (the volcano) never died."

For those who follow Haleakala’s every mood, the revelations of a possible impending eruption come as nothing new. For the last few years, volcanologists have been conducting more fieldwork on the mountain and adjusting the estimated ages of key lava flows, but their theories are usually confined to in-house reports or interviews with the press.

This time, however, the public got a chance to hear firsthand about the fire down below. Even better, they got to hear it from Sinton, one of those rare scientists who manages to present potentially mind-numbing facts with the storytelling ability of Jules Verne.

And given the opportunity, the Maui community responded. Despite the fact that the talk was held on Friday, the same night of Baldwin High’s graduation, some 50 volcano junkies showed up for the lecture sponsored by The Friends of Haleakala National Park. A hike at Kalepeamoa on the southwest rift zone was held the next morning.

No one was disappointed — or lost in the discussion.

"He was so good at pointing out things on the mountain that you’ve been looking at all the time, but you just didn’t see," said Vincent Mina, who attended both events. "He’s so passionate about his work, yet he didn’t bury us in jargon. You could understand what he was talking about."

Of course, the big attraction was the much-anticipated answer to the big question: Will Haleakala really blow again and, if so, should we cancel our plans to go to Big Beach tomorrow?

"It just tweaks your attention," said Charley Fein, a member of the board of the friends group. "In the back of our minds we all want to know: When’s the next one?"

While Sinton could explain the difference between olivine basanitoid and aphyric basanitoid, he wasn’t ready to go out on a limb and forecast something that only Madame Pele really knows for sure.

"It would be a mistake to make too many predictions," he said.

Both he and Fein said that Haleakala continues to slowly rise and creep north.

"And we all know it should be subsiding," said Sinton. "There are a couple of reasons (for the rising) and one of them is magmatic."

To monitor the internal churnings of Haleakala, the U.S. Geological Service has added more instruments to listen to the subsurface rumblings.

"We need more ears," said Sinton.

Volcanoes in Hawaii generally go through four stages. They begin as underwater seamounts, then explode spectacularly above the surface and build up into shield volcanoes, their most productive period when 90 percent of total activity occurs. As eruptions begin to subside, the mountain enters a "post-shield" stage. Finally, after a lengthy dormant period, some volcanoes have a rejuvenation stage — a sort of last hurrah — that might produce 1 percent of its total life’s output.

Scientists previously believed that Haleakala had gone through its "post-shield stage" and then rejuvenated, but recent tests of charcoal samples keep pushing the ages of the "post-shield" stage and rejuvenation period closer together, leading to the conclusion that Haleakala has never really stopped.
And that, of course, means future eruptions would not be unexpected.

The last eruption was the event that formed Cape Kinau at Keoneoio. The date of 1790 was arrived at because there was no cape recorded on maps left by French voyager Jean-Francois La Perouse in 1786, but an outcropping was obvious when British mariner George Vancouver plotted the same coastline in 1793. Interviews conducted in the mid-1800s with South Maui residents produced stories of the volcanic activity that had been passed down from elders, adding to the belief that the eruption occurred late in the 18th century.

So most everyone was surprised when new charcoal data indicated the lava was much older, perhaps by 330-500 years. What about the maps? Sinton said the discrepancy might have been caused by the well-known fact that La Perouse drew terrible maps, meaning that Cape Kinau could very well have been there when he landed. But what about the oral histories? Sinton said researchers now wonder if those interviewed were actually talking about stories they heard from their ancestors instead of their grandparents.

"They used the word ‘kupuna,’ and we’re wondering now if that meant an ancestor instead of a grandparent," said Sinton.

Whatever, the debate continues.

All the hot lava talk didn’t discourage the 10 hikers who chose to accompany Sinton the next day. Christa Matthews, a member of the board of directors of The Friends of Haleakala National Park, wouldn’t have missed a chance to visit Kalepeamoa, even though she’s well aware that the mountain is stirring.

"I know if I go up there on the ridge, something might happen at any moment," said Matthews. "Going up there gives you a totally different perspective on everything."