The 5.0-magnitude quake was the strongest of a series of earthquakes that struck Friday on Hawaii’s Mauna Loa, the planet’s largest active volcano that scientists say is in a state of “high unrest”.
According to the US Geological Survey, smaller aftershocks followed.
The series began with a magnitude 4.6 earthquake seconds before the larger quake, which the USGS had previously reported as magnitude 5.1.
The Hawaii Volcano Observatory said the first quake was off and south of the town of Pahala, followed by a larger quake just south of Pahala below the highway.
Hawaii County Mayor Mitch Roth said there were no immediate reports of major damage or injuries. He said there was then some minor damage in Pahala, including fallen bricks at a district building.
“Shakes from larger earthquakes can be strong enough to cause minor local damage, especially to older buildings,” the observatory said in a statement. “Two quakes occur within 24 seconds of each other, producing tremors with a longer duration and possibly greater magnitude than either quake could have produced on its own.”
Aftershocks could continue for days to possibly weeks and could 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 shaking left broken jars on the floor and knocked out the electricity, Laurie Tackett said.
“The ground just shook,” she said over the phone while ringing for purchases after the small store reopened. “It was a little scary.”
Mauna Loa is not erupting and there is no indication that an eruption is imminent at this time.
“This sequence of earthquakes appears to be related to a correction along the southeastern slope of the Mauna Loa volcano,” the observatory said. “In some cases, large earthquakes preceded past Mauna Loa eruptions, although they are often larger than today’s earthquakes. It is currently unknown if this sequence of earthquakes is related. directly related to the ongoing unrest on Mauna Loa.”
Scientists at the observatory have been closely monitoring Mauna Loa for the changes.
Hundreds of respondents on the USGS earthquake website said they felt tremors of varying degrees across the vast island. Those closer to Pahala reported strong shaking, while those farther away felt weaker shaking.
The Pacific Tsunami Warning Center said there was no tsunami risk for Hawaii.