Hawaii’s Mauna Loa volcano continue to show heightened unrest with swarms of small earthquakes

By Alfred Acenas
Eagle News Service

HONOLULU (Eagle News) – The Hawaiian Volcano Observatory (HVO) has detected more than a dozen small-magnitude earthquakes (below 3.0) some 1–3 miles (1–5 kilometers) below Mauna Loa’s Mokuʻāweoweo caldera and 1–5 miles (1–8 kilometers) beneath the upper-elevation northwest flank.

Both locations have historically been seismically active during periods of unrest on the volcano.

Heightened unrest began in mid-September 2022 with increased earthquake rates from 10–20 per day to 40–50 per day below Mauna Loa summit. This was likely caused by renewed input of magma into the summit’s reservoir system.

(FILE) On a clear day, Mauna Loa can be seen from nearby Mauna Kea, Hawaii’s highest peak. Mauna Kea is open for visitors whereas public access to Mauna Loa is restricted. (Photo by Charmaine Cirera-Raquel, EBC Hawaii-Pacific Bureau, Eagle News Service)

As the reservoir expands, it triggers small earthquakes directly beneath the Mokuʻāweoweo caldera and in a region just to the northwest of the caldera. Magma input greater than 2 miles or 3 kilometers has been detected by the continued increase in upward movement and extension measured between GPS stations located on the ground surface. Shallower magma input, less than 2 miles or 3 kilometers, was likely responsible for inflation recorded on the summit tiltmeter during the last two weeks of September.

Scientists and government officials continue to assure that Mauna Loa’s current conditions do not necessarily mean that the next eruption will occur there. Mauna Loa remains at an elevated alert level of Advisory / Yellow. The current increase in activity does not suggest that a progression to an eruption is certain, and there are no indications that an eruption is imminent.

HVO will continue to closely monitor Mauna Loa for changes, as well as issue daily Mauna Loa Volcano updates until further notice. More information on the current monitoring of Mauna Loa volcano is available at https://www.usgs.gov/volcanoes/mauna-loa/monitoring.

At 13,679 feet (4,170 meters), Mauna Loa is the world’s largest active volcano, covering most of the southern half of Big Island. Eruptions tend to produce voluminous, fast-moving lava flows that can impact communities on the east and west sides of the island.

Since its first well-documented eruption in 1843, the volcano has erupted 33 times with intervals between eruptions ranging from months to decades. Mauna Loa last erupted in 1984.

Mauna Loa’s peak is roughly 20 miles (32 kilometers) northwest of Kilauea volcano, regarded as one of the most active in the world.

(Eagle News Service)