Increased Hawaii seismic activity not considered a danger

HILO — An increase in seismic activity around the youngest Hawaii volcano poses no immediate danger to the Big Island, geologists said.

The U.S. Geological Survey Hawaiian Volcano Observatory said more than 100 earthquakes were detected around Loihi Seamount between Monday and Tuesday, The Hawaii Tribune-Herald reported Wednesday.

The increase was significant for the underwater volcano off the southeast coast of Hawaii Island, which typically experiences fewer than three earthquakes daily.

Tina Neal, Hawaiian Volcano Observatory scientist-in-charge, said similar “earthquake swarms” are not uncommon in areas with active volcanoes. The swarms can range in length between hours and months, Neal said.

The earthquakes becoming more shallow could indicate the beginning of a submarine eruption, which could cause summit collapses that generate tsunami waves, Neal said.

But she emphasized the volcano is likely too deep under the surface to generate any noticeable impact on the Big Island.

The earthquakes this week included 79 that were magnitude 2 and another 19 that were magnitude 3 or stronger. Most Loihi earthquakes fail to reach magnitude 2.

The quakes originated at approximate depths of between 0.6 miles and 6 miles (0.97 and 9.66 kilometers) beneath the volcano’s surface, or 2.2 miles to 7.7 miles (3.54 to 12.39 kilometers) below sea level.

The quake rate dropped to less than four per hour by midday Tuesday.

The last recorded eruption of the volcano occurred in 1996, which was preceded by a nearly month-long swarm of more than 4,000 earthquakes, Neal said.

The most likely cause of the recent swarm is a subterranean movement of magmatic fluids within the volcano, although Neal added the earthquakes could also be caused by gas or fluid escaping from Loihi.

Jackie Caplan-Auerbach, a Western Washington University professor who has studied Loihi for decades, said its periodic earthquake swarms are “interesting, but not alarming.”

“I think Loihi would have to split in half to create a damaging tsunami,” Caplan-Auerbach said. “And we don’t think that’s going to happen anytime soon.”

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