Exploring Mauna Kea

3 miles,
1 million years

Scientists will drill deep into
the Big Isle's Mauna Kea volcano
in a bid to unlock a million years of history

By Helen Altonn
Star-Bulletin

Scientists later this year will begin digging up about 1 million years of planetary history from a hole in Mauna Kea.

They plan to drill nearly 3 miles deep into the volcano and extract core samples to answer basic questions about Earth's interior workings.

"The overall objective is to understand planetary processes that drive hot-spot volcanism that formed the whole Hawaiian chain," said University of Hawaii geochemist Donald Thomas.

While a geologist can explain in detail how Mount St. Helens' volcanism works in Washington, he said, "We can't do the same thing for the Hawaiian hot spot."

A test hole about 3,500 feet deep in 1993 has

already changed the picture of Hawaiian volcanoes, said Thomas, coordinator of the drill projects.

"The science we got out of the hole was tremendously exciting."

Among highlights, he said, Mauna Loa is sinking faster than it is building up from new lava flows, which occur on the order of every 3,000 years.

"What that means is we now have a relatively good fix on what the volcanic hazard really is in that area," he said.

Scientists learned the productivity of Hawaiian volcanoes in the past was much lower on an average than what Kilauea has turned out in historic times, he said.

"It had been assumed if the current activity had continued over its life span, it would generate a Mauna Kea or Mauna Loa in about 500,000 years."

Findings also showed the life cycle of a Hawaiian volcano is twice as long as anyone projected, Thomas said.

He said 25 to 30 scientists worldwide participated in the test project and will analyze samples from the new six-year Hawaii Scientific Drilling Program.

The National Science Foundation and the International Scientific Drilling Program provided $11.8 million for the ambitious venture after the test project's "unqualified success."

Co-investigators are Don DePaolo, at the University of California-Berkeley and Ed Stolper of Caltech.

DePaolo, who pursued the funding to drill in Hawaii, said, "Hawaiian volcanoes are young enough that they're still essentially sitting in the same orientation they formed in and lavas still are stacked up in the order that they erupted.

"So, if you drill down from the surface, you just go back through older and older lavas. It's like looking at tree rings."

Thomas said two quarry sites south of Hilo Airport are being considered for the new hole, with selection pending the final environmental assessment. He expects the permit process to take about six months.

He said a number of mining companies are interested in the drill job, which involves using a bit similar to a cookie cutter to bore a hole, about 2 to 31/2 inches, through the rock.

Three phases are planned, starting with a core about 6,000 feet down, Thomas said. Drilling will stop then for 18 months to study the samples. "Then nobody is completely overwhelmed with samples and there is opportunity for feedback on problems or an operation we ought to do."

About 11,000 feet will be drilled in the second phase, followed by another 18-month hiatus for research and analysis. Then, the final push will be made to reach a depth of about 14,500 feet.

A hole that deep has never been drilled in Hawaii, Thomas said, adding: "I don't want to minimize the technical challenge. The lesson from the first hole is that things are going on we don't know. And because we don't know, we could easily run into drilling difficulties. We're entering new terrain."

DePaolo said Hawaii is "the quintessential example" of volcanism related to mantle plumes, a phenomenon deep in the Earth. "These jets of hot material come up in the mantle all the way from near the surface of the Earth's core."

Thomas said the deeply rooted plume has spewed molten magma onto the ocean floor for about 70 million years to create the Hawaiian Islands up to Midway and Wake. The youngest is underwater volcano Loihi near the Big Island.

The hot spot or plume appears to be almost stationary, while the sea floor making up the Earth's Pacific Plate is gradually moving northward, he said.

About two dozen hot spots have been identified around the world, including one under Yellowstone National Park, Thomas said.

"The striking or unusual characteristic is if you, in effect, peel away the tectonic plates and look simply at hot spots on the planet, they appear to stand still with respect to each other.

"It says there is a disconnection, that the process going on is not influenced by the movement of the tectonic plates on the surface of the Earth, and that is something initially that was very hard to fathom."

Thomas, with the Institute of Geophysics and Planetology, says he's the "mechanic" to get the drill project done. But he also has scientific interests, particularly in groundwater and water-rock interaction beneath volcanic ocean islands.

DePaolo will measure isotope ratios of the elements strontium and neodymium to learn what the mantle plumes are made of. "It's going to tell us a fairly detailed story about how volcanoes are produced, how magma is made in the mantle and fed to the volcanoes," he said.

A field lab will be set up at the drill site so geologists can process and characterize core sections as they're brought up, he said.

Part of the core will be preserved for future scientists, Thomas said. "It will be a unique resource."

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Scientists discover water
under volcano

A hole drilled 3,500 feet deep
reveals cold salt water lying below
a layer of fresh water

By Helen Altonn
Star-Bulletin

Buried about 1,000 feet below Mauna Kea's surface on the often drought-stricken Big Island is a thick layer of fresh water.

That was among discoveries during a test hole drilled in the volcano in 1993 to show a deeper hole would be feasible and scientifically useful.

"It could have some very, very striking implications for water development on the island of Hawaii," said Donald Thomas, University of Hawaii geochemist who coordinated the Hawaii Pilot Hole Project.

He said researchers intended to drill about 1,900 feet, but they hit that depth earlier than they expected. Since they still had time and money, they continued drilling to about 3,500 feet, he said.

Don DePaolo, a co-investigator for the drill projects at the University of California-Berkeley, said another surprise was "really cold salt water" below the fresh water layer.

"Most people think it should be hot down there. This water was 7 degrees centigrade, not a whole lot warmer than inside a refrigerator. It's cold sea water, and it's flowing through cracks in rocks at a pretty substantial rate.

"There are some ideas of using this cold water for refrigeration or air conditioning," DePaolo added.

The scientists expect to learn a lot more about the potential resource from the deeper hole, down to about 14,500 feet.

Thomas said a process appears to be going on in which high-

level rainfall, about 6,000 feet above sea level, falls on Mauna Kea, seeps down into the volcano and becomes trapped under the soil and ash.

As rainfall piles up, it forces the rain water below sea level, and it moves beneath the layer of soil until it reaches the ocean, he said. There, it's discharged as submarine springs about 1,000 feet deep offshore, he said.

More research is needed to see if other environments have a similar situation, he said.