Big Island earthquake swarm
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Volcanologists are keeping a close eye on their instruments after a rare earthquake swarm off the Big Island the past two days.

Twenty miles off the southeast coast of the Big Island, Hawaii's newest volcano rises 10,000 feet from the ocean floor with its summit about 3,000 feet under the surface.

When Loihi starts shaking, scientists pay attention.

"Think of it as a younger version of Kilauea or Mauna Loa volcanoes," said David Phillips, deputy scientist in charge at Hawaiian Volcano Observatory.

Phillips said there's no significant hazard at the moment, but at one point HVO recorded 14 earthquakes per hour on the Loihi Seamount.

"The peak did take place yesterday afternoon, whether it continues to subside or come back is hard to say," Phillips said.

On a seismogram, more than a hundred temblors struck in the 2- to 3-magnitude range, suggesting magma is on the move.

Phillips said if the shaking continues, it could signal an eruption — and that could cause a summit collapse.

That's happened before, last in 1996.

A significant eruption could even cause a small tsunami.

"There would be very little time to respond," Phillips said. "It would be certainly less than an hour, could be minutes."

But there is no sign of trouble right now.

"From everything we've seen, there's nothing like that coming," Phillips said.

The seamount appears to have settled down. Besides the occasional rumble, the most exciting things on Loihi are the creatures that thrive in the hot water nearly a mile deep.