World’s largest active volcano signals it may erupt

Scientists and emergency managers say those living below the world’s largest active volcano shouldn’t put their guards down. (Source: KHNL/KGMB)
Published: Oct. 28, 2022 at 2:19 PM CDT
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PAHALA, Hawaii (KHNL/KGMB/Gray News) - Officials in Hawaii are warning residents of the Big Island that the world’s largest active volcano, Mauna Loa, is sending signals that it may erupt.

KHNL/KGMB reports there were about 20 small quakes at the volcano over a 24-hour period ending Thursday morning.

The Hawaiian Volcano Observatory said that the unrest is most likely driven by renewed magma input two miles beneath the volcano’s summit.

Officials held a community meeting in Pahala Thursday night where they stressed an eruption is not imminent, but those who live near the volcano shouldn’t put their guards down.

Pahala resident Jandale Waltjen-Kuilipule was asked if she was concerned about an eruption.

“Very concerned, yes, very concerned,” she said. “We haven’t had one for a very long time with Mauna Loa.”

The meeting comes on the heels of a gathering in Ocean View last week, where some residents questioned whether county officials had a good enough plan in the event of an eruption.

People in the Ka’u District are especially at risk as Highway 11 is their only way out. If an eruption were to close that highway, evacuating about 20,000 people who call that area home would be extremely difficult.

“Since there’s just one main road, what is their plan for another mass exodus because that is what will happen,” said Waiohinu resident Lynne Adams. “I mean, people are going to panic. That’s human nature.”

The U.S. Geological Survey has Mauna Loa at a yellow advisory ― meaning be prepared.

“We would hope if Mauna Loa rocks that we would have days so that folks can be evacuated and notified,” said Dr. Andria Ellis, a geophysicist with USGS at the Hawaiian Volcano Observatory.

But Ellis said Mauna Loa’s structure could leave residents far less time to evacuate than when Kilauea erupted in 2018.

“One of the challenges with Mauna Loa that makes that different from Kilauea is the way it’s structured. It has flanks or sides that are really steep, and that depending on where lava emerges at the surface, it could travel very quickly into places of residence, and we might not have that day or more,” she said.

Hawaiian Volcano Observatory geologist Frank Trusdell has tracked Mauna Loa’s history. He said most of the eruptions start at the summit.

“Half of the eruptions start there and stay there,” he said. “All Mauna Loa eruptions in this period have started with a summit phase first.”

As for the earthquakes, Hon showed a map of the area, with dozens of white lines over the Ka’u District and the Pahala area.

“The white things are faults,” Hon said. “So, these are mapped faults on the island of Hawaii. You’ll notice that you live inside the biggest nest of faults on the island of Hawaii.”

Hon said the earthquakes mostly are due to the weight of the mountain slowly sliding toward the ocean.

Officials with the Hawaiian Volcano Observatory also said earthquake activity remains elevated but has eased in the last week.

“It’s kind of rounded off a little bit, which is important, but with this type of threat, we need to take a cautious look at what may be coming,” said Luke Meyers, administrator of the Hawaii Emergency Management Agency. “It’s better to be prepared and to be ready.”