This is a Bit Concerning

Earthquake activity is on a bit of an uptick around here. While the mag 3.9 that woke us up a few nights ago was probably just a settling event under Mauna Kea, much of the remaining activity is under Mauna Loa. This includes a 3.7 magnitude event last night, part of an ongoing swarm under the long mountian.

Mauna Loa earthquake swarm 5 Oct 2022
Mauna Loa earthquake swarm 5 Oct 2022

Mauna Loa’s activity has remained elevated for some weeks now. There are two swarm centers. One directly under the caldera, but more interestingly a persistent swarm under the northwest flank a few kilometers away.

All of this has the island buzzing with concern. On social media, in the local papers, Mauna Loa is the subject of much speculation. The official line is that no eruption is imminent, but officials are quick to remind residents to monitor local emergency channels and have an evaculation plan at the ready.

Mauna Loa earthquake swarm profile 5 Oct 2022
Mauna Loa earthquake swarm profile 5 Oct 2022

The earthquake plots are interesting. A plot map clearly shows the two swarm centers at the caldera and on the northwest flank. A profile plot of the flank swarm is even more interesting in many ways. The elevations of the earthquakes show locations well above sea level, well up in the body of the mountain, near the surface. The shallow quakes are becoming more common and include last night’s temblor.

I am not quite as concerned for our safety, we are not downhill from Mauna Loa at the house. But any eruption could have a rather large effect on island life. Memories of the destructive 2018 Kilauea eruption are fresh, and many of the possible paths below that swarm on the northwest flank lead to heavily developed areas along the coast.

While Waikoloa Village itself is not downhill, the possible effected area begins just a few kilometers south, and stretches as far as Captian Cook, Kealakekua Bay and further south along the coast. Kona itself is behind Hualalai and not subject to flows from Mauna Loa, but much of the remaining coast is.

These earthquake swarms may subside, or may build to an eruption. Either way the mauna is reminding us that an eruption will happen, the question is simply when. My personal bet? Within the coming year we will see Mauna Loa confirm her status as an active volcano. Well? I have been wrong before.

Update: Well? I was not wrong. It took less than two months from this prediction as the eruption began at 11:30pm, Sunday, November 30th 2022.

Snow Covered Mauna Loa
Looking across at a snow covered Mauna Loa from about 9,000ft on Mauna Kea

Author: Andrew

An electrical engineer, amateur astronomer, and diver, living and working on the island of Hawaiʻi.

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