A magnitude 5.0 earthquake was the strongest of a series of temblors that have struck Hawaii’s Mauna Loa, the largest active volcano on the planet, which scientists say is in a “state of heightened unrest”.

A series of earthquakes on Friday started with a 4.6 magnitude earthquake 24 seconds before the larger 5.0 earthquake, the Hawaiian Volcano Observatory said in a statement issued by the United States Geological Survey (USGS).

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“The two larger earthquakes were reported by hundreds of people from the Island of Hawai’i and felt to a lesser extent across the entire State of Hawai’i,” the observatory said.

“Shaking from the larger earthquakes may have been strong enough to do minor local damage, especially to older buildings,” it said.

Earthquakes have preceded previous eruptions of Mauna Loa, though they have generally been larger than the quakes experienced on Friday, the observatory said.

“There has been no immediate effect on the continuing unrest beneath Mauna Loa summit, which remains elevated at levels similar to the past week,” the observatory added.

Hawaii County Mayor Mitch Roth said there were no immediate reports of major damage or injuries. He said later there was some minor damage in the town of Pahala, but he was not able to immediately provide details.

Aftershocks could continue for several days to possibly weeks and may be large enough to be felt. Scientists at the observatory are monitoring Mauna Loa closely for changes.

Hundreds of responses on the USGS earthquakes website reported weak-to-light shaking across the vast island.

The Pacific Tsunami Warning Center said there was no tsunami threat to Hawaii.

Mauna Lao is at a yellow advisory warning which means it is being observed but there are no signs of an imminent eruption. (Al Jazeera)

•PHOTO: NASA image shows snow on the tops of the Mauna Kea (upper) volcano and Mauna Loa (lower) volcano on Hawaii's Big Island in 2002. With summits of 4,205 metres (13,792 feet) for Mauna Kea and 4,169 metres (13,674 feet) for Mauna Loa, it's not unusual to get wintertime snowfall [File: NASA/AFP]

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