Kilauea quake predicted to be slow and harmless

Scientists say a 'slow quake' is on its way

HILO » Scientists at the Hawaiian Volcano Observatory on the Big Island are predicting a major earthquake there in the next few days, but they add that almost certainly no one will feel it.

Based on prior events, the predicted ground motion seaward of Kilauea caldera will be a "slow earthquake," taking place over perhaps two days, detectable only by instruments, they say.

Despite its unusual nature, the amount of energy released will be comparable to a normal quake. A similar two-day event in 2005, if it had been compressed into a few seconds, would have been a magnitude-6 event, the same as the second of two quakes that caused millions of dollars of damage on the Big Island Oct. 15.

HILO » University of Hawaii geophysicist James Foster is hoping the Big Island has an earthquake today or tomorrow, a nice "slow earthquake" that no one will notice except scientists attuned to their instruments.

Foster, geologist Ben Brooks and others at the School of Earth Science and Technology announced in a scientific paper last year that such nondestructive, slow earthquakes take place on the western side of Kilauea volcano every 774 days, give or take a week.

Another was supposed to slip into instrument view about last Saturday, the Hawaiian Volcano Observatory said yesterday.

That was the first such prediction ever for Kilauea, although two accurate predictions of slow quakes have been made offshore from Washington state, said observatory geophysicist Michael Poland.

If the current prediction comes true a few days late, that will just mean that the prediction period has to be adjusted, Foster said.

If a longer period passes with no movement, it could mean the earth's clockwork was upset by something, like the Oct. 15 earthquakes.

Foster is hoping for a quake not just to prove his theory. A quake arriving on time could provide valuable information about how and why quakes take place. Predicting slow quakes could eventually lead to predicting fast, destructive ones.

Slow quakes seem to be caused by the same thing that causes fast quakes, earth slippage under ground, Foster said. But the exact process is a "million-dollar question," he said.

Other scientists had spotted the slow quakes before Brooks and Foster discovered their apparent regularity.

Brooks and Foster found a "western family" took place on Sept. 20, 1998; Nov. 9, 2000; Dec. 16, 2002; and Jan. 26, 2005. Three others have been noted in an "eastern family" but without any regularity, Poland said.

With several agencies cooperating, the observatory put out six additional global positioning system instruments to record ground movement and 21 more seismometers to record the small jiggling that goes with a slow quake.

Could one of these slow quakes turn into something destructive? Poland tried comparing destructive Kilauea quakes in 1975 and 1989 with the 774-day prediction period. They did not match, he said.