A 5.0-magnitude earthquake was the strongest in a series of tremors that rocked Hawaii’s Mauna Loa on Friday, the planet’s largest active volcano that scientists say is in a “state of great concern.” Smaller aftershocks followed, according to the US Geological Survey.
The series began with a magnitude 4.6 quake 24 seconds before the larger one, which the USGS previously reported as having a magnitude of 5.1.
The first was slightly offshore and south of the town of Pahala, followed by the larger quake just south of Pahala under a highway, the Hawaii Volcano Observatory said in a statement.
Hawaii County Mayor Mitch Roth said there were no immediate reports of major damage or injuries. He later said there was some minor damage in Pahala, but could not immediately provide details.
“Shaking from larger earthquakes may have been strong enough to cause minor local damage, especially to older buildings,” the observatory statement said. “The two earthquakes occurred within 24 seconds of each other, creating a tremor of longer duration and possibly greater intensity than either earthquake would have created on its own.”
Aftershocks could continue for several days or possibly weeks and may be large enough to be felt, the observatory said.
Mizuno Superette, the only grocery store in rural Pahala, closed for about an hour and a half after the tremor left broken jars on the ground and knocked out power, cashier Laurie Tackett said.
“The ground was shaking,” he said by phone as he checked in on purchases after the small store reopened. “It was a bit scary.” Mauna Loa is not erupting and there are no signs of an imminent eruption at this time.
“This sequence of earthquakes appears to be related to readjustments along the southeastern flank of the Mauna Loa volcano,” the observatory said. “On several occasions, large earthquakes have preceded Mauna Loa’s past eruptions, although 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 disturbances at Mauna Loa.” Scientists at the observatory were closely monitoring Mauna Loa for changes.
Hundreds of responses on the USGS earthquake website reported weak to light shaking on the vast island.
The Pacific Tsunami Warning Center said there was no tsunami threat in Hawaii.