Thursday, November 26, 2015         

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Lava lake sinks, spurring quakes

By Jim Borg


Eight small earthquakes rocked Kilauea Volcano after the lava lake at the summit caldera dropped in elevation Sunday, U.S. geologists reported.

But that seismic shaking was actually below normal levels, they said.

The strongest quake was a magnitude 3.3 at 2:16 a.m. Sunday.

At Puu Oo, meanwhile, a "skylight" in the pahoehoe (smooth, ropy lava) field showed a tube transporting lava on the southeast flank to active flows about three miles to the south.

The active lava flows are within the Kahauale‘a Natural Area Reserve, which remains closed to the public because of various hazards — including potentially lethal concentrations of sulfur dioxide — so they are visible only from the air.

But the glow from the vents and flows can be seen from the Hawaii County viewing area at Kalapana if weather conditions are right, said scientists with the U.S. Geological Survey.

There were no active ocean entries on Sunday.

At the Kilauea summit caldera, the surface of the lava lake, about 500 feet in diameter, has been fluctuating between about 230 feet to 490 feet below the floor of Halemaumau Crater, scientists said on the Hawaiian Volcano Observatory website. It's now about 330 feet down, according to Jim Kauahikaua, scientist in charge.

THE VENT has been mostly active since opening with a small explosion on March 19, 2008.

In the weekly Volcano Watch report, Kauahikaua said Thursday the lava lake is as active as the one Mark Twain observed in 1866.

While the geometry and depth of the lake are different today, some things remain unchanged, said Kauahikaua.

"Photos from the early 1900s show the same robust white plume that we see today, carried by the trade-winds to the southwest," he said. "A visitor in the 1800s described ‘suffocating fumes of sulphuric acid gas.' Presumably, vog was a problem in West Hawaii in the past as well."

The observatory will celebrate its centennial in January.

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