A magnitude-5.0 earthquake was the strongest of a series of temblors that struck Friday on Mauna Loa, the largest active volcano on the planet, which scientists say is in a “state of heightened unrest.”
Smaller aftershocks followed, according to the U.S. Geological Survey.
The series started with a 4.6-magnitude quake 24 seconds before the larger one, which the USGS previously reported as having magnitude of 5.1.
The first one was slightly offshore and south of the town of Pahala in the Kau district of Hawaii island, followed by the larger quake just south of Pahala beneath Highway 11, the USGS Hawaiian Volcano Observatory said in a statement.
Hawaii County Mayor Mitch Roth said there were no immediate reports of major damage or injuries.
“Shaking from the larger earthquakes may have been strong enough to do minor local damage, especially to older buildings,” the HVO statement said. “The two earthquakes occurred within 24 seconds of each other creating shaking of longer duration and possibly greater intensity than either of the earthquakes would have created on their own.”
The aftershocks could continue for several days to possibly weeks and may be large enough to be felt, HVO said.
Mizuno Superette, the only grocery store in rural Pahala, closed for about an hour and a half after the shaking left broken jars on the floor and knocked out electricity, said cashier Laurie Tackett.
“The ground was just shaking,” she said by phone while ringing up purchases after the small store reopened. “It was a little scary.”
The Pahala Post Office reported that its retail lobby will be closed indefinitely after interior light fixtures were damaged. The P.O. box lobby was not impacted and mail delivery will continue without interruption.
Mauna Loa is not erupting, and there are no signs of an imminent eruption at this time, scientists say.
“This sequence of earthquakes appears to be related to readjustments along the southeast flank of Mauna Loa volcano,” HVO said. “On several occasions large earthquakes have preceded past eruptions of Mauna Loa, though these have typically been larger than today’s earthquakes. It is not known at this time if this sequence of earthquakes is directly related to the ongoing unrest on Mauna Loa.”
Scientists at the observatory were monitoring Mauna Loa closely for changes.
Hundreds of responses on the USGS earthquakes website reported weak to light shaking across the vast island.
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