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Thursday, January 4, 2001

By Jane Takahashi, U.S. Geological Survey, Special to the Star-Bulletin
Hawaii Volcanoes National Park on the Big Island is
a hotbed of unique rock formations and compositions.
Here, a geologist gathers rocks to study from the
Kipuka Nene area of Kilauea volcano.

Proof of Kilauea’s
big bang shocks
Hawaii geologists

The volcano once had a
Mt. St. Helens-style eruption,
never before known in the islands

By Rod Thompson
Big Island correspondent

HILO -- Sometime before 1000 A.D., Kilauea volcano blasted skyward in an eruption so massive it sent rocks and dust as much as 18 miles into the air.

The cloud of debris may have been seen on Maui, said Don Swanson, scientist-in-charge at the Hawaiian Volcano Observatory.

And the eruption may have changed the way Hawaiians viewed Kilauea, ushering in the new volcano goddess Pele, said Hawaiian cultural consultant Kepa Maly.

For several years, geologists have known about fist-size rocks shot through the air, different from surrounding rocks, lying on the ground south of Kilauea, Swanson said.

In August, geologists took a closer look.

"What we found surprised, even shocked us," Swanson said. About five miles from the summit, they found a rock weighing 4.3 pounds. At six miles from the summit, they found one weighing nearly 3 pounds.

Standard theories said a Kilauea eruption couldn't throw heavy rocks that far. "The models simply say no dice. It can't be done," Swanson said.

Geologists were forced to conclude that Kilauea experienced a Mt. St. Helens-style eruption, never before known in Hawaii.

Besides rocks, there was ash. By dating charcoal above and below the ash layer, geologists arrived at a very rough date, between 600 and 1000 A.D.

After a site where the rocks were found, geologists are calling it the Kulanaokuaiki eruption, "Kulana" for short.

The eruption would have taken place during just a few hours, no more than a day, Swanson said.

The rocks contain green crystals which form only deep underground. They would have been blasted upward from a depth of "a few thousand feet" by underground gases, Swanson said.

Other explosive eruptions at Kilauea, such as a much smaller one in 1924, have all been shallow.

How did Hawaiians react to the event?

Very little is known about human use of the immediate area, said Hawaii Volcanoes National Park archaeologist Laura Schuster.

The area is extremely dry, but people fished along the shoreline.

The earliest reliable radiocarbon date, from a bit northeast of the rock fallout area, is 1280 A.D., well after the eruption, she said.

By Dean Sensui, Star-Bulletin
Kilauea volcano's Pu'u O'o vent spews lava in
July 1983, starting an eruption phase that
continues to this day.

It comes from a cave used by fishermen at Kamoamoa, now covered by recent lava. Excavations in that area revealed rock structures, but it's unclear whether habitation was temporary or permanent.

Cultural consultant Maly was surprised by the discovery of the Kulana eruption.

"It's staggering," he said.

He suggested the actual event may have been permanently fixed in people's minds.

Everyone has heard of the volcano goddess Pele, but not everyone knows that she was sometimes called a "malihini," or latecomer.

Before her the volcano god was 'Aila'au, Maly said. His name means "forest eater," but he was relatively peaceful. Pele was more violent and drove 'Aila'au away, Maly said.

Was it this eruption or a different event that lead to the rise of Pele and the decline of 'Aila'au? Was Kilauea more active after the Kulana eruption?

It certainly remained active, Swanson said. But there is very little information about what it was like before the eruption.

Several years of study will be needed to clarify the picture, he said.

Volcano's current
eruption in 18th year

HILO -- Kilauea's east rift eruption has been ongoing for 18 years.

About once a month from 1983 to 1986, the eruption formed a fairly regular pattern of high fountains lasting about a day, followed by a return to quiet until the next fountaining.

The source of the lava was a relatively shallow system of tubes that came from Kilauea's summit. Although the fountains were high, they were not explosive.

Since 1986 the eruption has been an almost continuous flow of lava with no fountains.

The recently discovered Kulanaokuaiki eruption of a thousand or more years ago was a short blast from deep in the earth. Scientists call it a Plinian eruption after the Roman Pliny, who described Vesuvius erupting this way.

Although other Plinian eruptions are suspected in Hawaii, this is the first one confirmed, geologist Don Swanson said.

Another type of eruption took place in 1924 when rainwater trickled down to lava near the surface of Kilauea, turned to steam and created a steam explosion. This type of eruption is called phreatic.

Two very large phreatic eruptions took place at Kilauea 2,100 years ago and 2,700 years ago, Swanson said. Both were smaller than the Plinian Kulana eruption on Kilauea.

Rod Thompson, Star-Bulletin

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