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The Honolulu Advertiser
Posted on: Thursday, January 16, 2003

Scientists debate network of Big Island's volcanoes

Advertiser News Services

HAWAI'I VOLCANOES NATIONAL PARK, Hawai'i — It started last Mother's Day.

A Kilauea lava flow headed for the ocean on Aug. 17. Some scientists believe Mauna Loa's swelling caused a Kilauea outpouring last May.

Associated Press

On May 12, the biggest volcano in the world started to swell. After 18 years of slumber, Mauna Loa was awake.

That same day, the Big Island's youngest and most active volcano, Kilauea, stepped up an eruption that has flowed nearly continuously since 1983. As the towering Mauna Loa swelled, its smaller sibling spewed copious amounts of lava — 30 times the norm — from two new vents torn from its flank.

The odd confluence of events did not go unnoticed. Now, after months of analyzing the behavior of the neighboring volcanoes, two geophysicists at the Hawaiian Volcano Observatory say the two volcanoes — long seen as solo acts — may be closely linked, or at the very least, may somehow commune with each other beneath the surface.

"This came as a surprise to us," said Peter Cervelli, an observatory geophysicist who with colleague Asta Miklius described the finding in today's issue of the journal Nature. "We're talking about conversations between volcanoes."

A volcano expert who did not contribute to the Hawai'i study said it supports the idea that there is a shallow common magma reservoir within the volcanoes.

"I think it's real," said Paul Segall, a geophysicist at Stanford University. "We know there's ultimately a single source. This indicates that they're probably a little more complicated than that and there are interactions between their two systems."

"The Mother's Day flow was nothing spectacular or unusual on Kilauea, except that it had been preceded by several months of inflation," Cervelli said. "If it's not coincidence, this is kind of the first line of geophysical evidence that shows the two volcanoes are communicating."

Tests, simulations and other monitoring determined that the possibility of a coincidence was less than one in 10, Cervelli said.

Researchers said there are two possible explanations for the apparent connection between the volcanoes.

"One way of thinking about it is ... Mauna Loa began to inflate and on May 12 squeezed its neighbor Kilauea, which pushed it over the edge and that caused the Mother's Day event," he said. "My favorite hypothesis is that a slug of magma entered into Mauna Loa and actually, as it was passing by Kilauea, squeezed Kilauea and triggered this failure — it sprung a leak, in effect, and the Mother's Day event ensued."

It's hard to tell whether similar events have occurred before because equipment being used today — including continuous monitoring using global positioning devices — is far better than anything used in the past, Cervelli said.

The event does not suggest that Mauna Loa is on the verge of erupting. The inflation is an indicator that the volcano may erupt again, but scientists say they can't pinpoint exactly when that might happen, Cervelli said.

"It's of academic interest, it's not an indicator that Mauna Loa is about to blow," said Stanford's Segall. "It really tells us that despite the fact that Hawai'i volcanoes are probably the best studied volcanoes in the world, we still have a lot to learn from them."

Don Swanson, the chief scientist at the observatory, has spent decades clambering up the flanks of Mount St. Helens and Mauna Loa with monitoring equipment, and he hikes out to Kilauea's flowing orange lava every morning at sunrise to compile a daily eruption update. Swanson is among the many scientists who do not believe the volcanoes, with summits that lie just 21 miles apart, are linked.

There is a lot of evidence on Swanson's side, too. The lava of the two volcanoes is entirely different. The two volcanoes erupt in wholly different patterns: Mauna Loa erupting alternately from its summit and flanks and Kilauea erupting more often from its flanks.

But Swanson isn't ruling anything out. Like many, he's long noticed a curious pattern. Through much of the past 150 years, when one volcano flowed, the other was quiet, suggesting a possible negative relationship. And he admits the restless mountains he studies follow few rules.