The summit of Mauna Loa has been closed to climbers and tourists amid increasing seismic activity in the area around Hawaii’s biggest volcano, the National Park Service has said.
Mauna Loa’s peak was closed to members of the public on Wednesday last week following “elevated seismic activity on Mauna Loa”, the NPS said, while adding that the closure was “a precautionary measure”.
The volcano is not erupting but the NPS said “the volcanic alert level remains at advisory, and the aviation colour code remains at yellow” as a result of above normal seismic activity.
The United States Geological Survey (USGS) said the volcano typically sees about 10 to 20 quakes per day, but that has risen to 40 to 50 a day since September, when the current period of seismic unrest began.
Earthquakes have continued since the closure of the summit with 65 small-magnitude earthquakes recorded by the USGS in the past 24 hours, between Tuesday and Wednesday this week.
Small earthquakes were described as those up to five miles below the surface of the volcano’s Mokuāʻweoweo caldera and the upper-elevation northwest flank of Mauna Loa.
The USGS said “both regions have historically been seismically active during periods of unrest on Mauna Loa” and that other possible warning signs of a volcanic eruption, including sulphur dioxide and carbon dioxide levels, remain stable at the summit.
“Webcam and thermal camera views have shown no changes to the volcanic landscape on Mauna Loa over the past week,” the USGS added on Wednesday.
In a statement, the NPS said scientists at the US Geological Survey Hawaiian Volcano Observatory (HVO) “will notify the park if conditions change” and that Mauna Loa Road and the Mauna Loa Lookout remain open to the public.
The lookout is at an elevation of 6,662 feet and provides views of the Kīlauea volcano, which has been erupting since September 2021 and according to the NPS, has erupted dozens of times since the 1980s.
Mauna Loa has meanwhile erupted 33 times since 1843. averaging once every five years, the NPS says. The last eruption was in 1984.
“Unrest may or may not lead to an eruption,” said University of Hull volcanologist and earth scientist Rebecca Williams to Newsweek. “At Mauna Loa, my understanding is that there has been an increase in seismic activity and inflation [for example] the ground is swelling, and that the USGS think this signals that magma is moving at depth under the volcano,”.
She continued: “They have heightened the alert level accordingly. The volcano is very actively monitored. This kind of unrest does occur and does not always lead to an eruption—it’s not unexpected but should always be treated with caution.”
