Hawaii national park closes world’s largest active volcano due to increased seismic activity

Around 44 small-magnitude earthquakes recorded in past 24 hours around Mauna Loa

National park authorities have closed Mauna Loa summit of Hawaii’s largest active volcano as a precautionary measure “due to elevated seismic activity”.

Mauna Loa – also the largest active volcano on the planet – is “currently experiencing heightened unrest”, the US Geological Survey said in an advisory on Thursday.

It added that the volcano is not currently erupting and there are no signs of an imminent eruption so far.

“GPS measurements show continued surface deformation related to inflation of a magma chamber beneath the summit,” it said.

The Hawaii Volcanoes National Park authorities have increased the alert level for Mauna Loa to yellow, the second of four levels, closing it till further announcement.

According to the advisory, scientists have observed recent “elevated” earthquake rates, observing about 44 small-magnitude tremors around the summit in the past 24 hours.

The US Geological Survey’s Hawaiian Volcano Observatory (HVO) has moved from issuing weekly updates for Mauna Loa to daily updates in view of the recent activity.

Mauna Loa last erupted in 1984 and the lava descended to the doorstep of Hilo, the population centre of the island and home to a University of Hawaii campus.

The last time Mauna Lao displayed elevated earthquake activity was in 2021 from January to March.

“Earthquake activity has been increasing from 5-10 earthquakes per day since June 2022, to 10-20 earthquakes per day in July and August, and reaching approximately 40-50 earthquakes per day over the past two weeks,” the observatory said.

“Peak numbers of over 100 earthquakes per day occurred on September 23rd and 29th.”

Mauna Lao is one of the five volcanoes that make up the Big Island of Hawaii. It rises gradually to 4,170m (13,681 feet) above sea level.

If the volcano’s mass beneath the surface is taken into account, its size is estimated to be about 17,000m (56,000 feet) from base to summit.

It has erupted 33 times since such activity was first documented in 1843 and is currently in the longest period without eruptions in at least the past two centuries, Kate Mulliken, a geologist for the Hawaiian Volcano Observatory, told USA Today.