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Dec. 6, 2022

Ask the expert: Why is Mauna Loa erupting now and for how long?

“Ask the Expert” articles provide information and insights from MSU scientists, researchers and scholars about national and global issues, complex research and general-interest subjects based on their areas of academic expertise and study. They may feature historical information, background, research findings or offer tips.

Mauna Loa is a volcano located on the Big Island of Hawaii and is the largest volcano on the planet. The volcano, which has been dormant since 1984, began erupting on Nov. 27, 2022.

Jeffrey Freymueller, a professor in the College of Natural Science and the Department of Earth and Environmental Sciences at Michigan State University. Freymueller is an Endowed Chair for Geology of the Solid Earth. He is an internationally recognized expert in geodesy, or the study of Earth’s size and shape. Specifically, Freymueller studies ground deformation associated with active volcanoes, where magma accumulates prior to eruptions and where the magma comes from as a volcano erupts. He discusses the current Mauna Loa eruption and how it relates to his research at MSU. 

Is the Mauna Loa eruption normal or unusual?

This eruption so far seems like a typical Mauna Loa eruption. Mauna Loa eruptions usually start out with some activity at the summit, which then is followed by a fissure eruption — cracks along the volcano’s surface where lava escapes — on one of the volcano’s rift zones. This time, it is erupting from a series of fissures high up on the Northeast Rift Zone. It is still a bit too early to draw conclusions, but thus far this eruption seems to be within the normal range of past Mauna Loa activity. Mauna Loa eruptions commonly have high eruptive volumes, and the lava flows can extend a long distance downslope.

The interesting or unusual thing is how long it has been since the last Mauna Loa eruption. It last erupted in 1984, but prior to that — for at least 100 years — it almost always had erupted once every few to several years.

Why is this eruption important?

The eruption is important for both societal impact and for potential scientific lessons. The scientific lessons are not yet clear, but this eruption may inform future construction planning. A lot of property development has occurred in Hawaii since 1984, and a lot of that development was made without much attention to volcanic hazards. Right now, the lava flows remain far from any human-built structures, except for the Mauna Loa Observatory, but that could change and may be only a matter of luck. Had the magma gone further down one of the rift zones before coming to the surface, it might have had more impact right away. This eruption still may engulf Saddle Road, the one highway that passes through the interior of the island. Damage to infrastructure may result in a more thorough evaluation of how future developments can incorporate volcano-informed design to reduce risk and loss. Here is a recent map of the lava flows.

This eruption may be important for a couple of scientific reasons. One is that it may be possible to learn why the volcano waited so long to erupt. I’m not sure if it will be possible to figure that out, but anything we learn will be important. The second is whether the activity at Mauna Loa has any impact on neighboring volcano Kilauea. One possible explanation for the lack of Mauna Loa activity for the past 35 years is that Kilauea may be interfering in some way, that somehow only one of them can be persistently active at the same time. I have some doubts from a physical mechanism perspective, but there is an intriguing anticorrelation of activity.

How does your research relate to this eruption?

I have installed several Global Positioning System sites on the island, mostly away from the volcanoes, to look at the long-term subsidence, or sinking, of the island. This eruption might interfere with that or might provide a new and interesting signal. I have also worked on a variety of other volcano deformation problems, although mostly in Alaska. This will be my first opportunity to look at Mauna Loa in this way! 

By: Emilie Lorditch

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