A Michigan State University professor is leading groundbreaking research on the Alaskan earthquake

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On July 29, 2021, the Chizhnik, Alaska earthquake struck with a magnitude of 8.2 – making it the strongest earthquake to hit the United States in nearly 60 years.

Jeffrey Freimüller, a professor in the Department of Earth and Environmental Sciences at Michigan State University, first began studying the area in 1995.

“That’s kind of how I got to this very place,” he said.

Earthquakes occur when the tectonic plates that make up the Earth’s crust move.

Freymueller measures the motion and deformation of the Earth, which includes plate movements and volcanoes, and investigates active faults.

Using a very precise GPS survey to measure the location of points on the Earth over time, Freymueller said “we can actually watch how they move, and then use that information to figure out what’s going on inside the Earth that’s actually causing those motions.”

What Freymueller and his colleagues hope to discover is the exact part of the interface that has slipped between the two plates, and how much, and relate that to what they observed before the earthquake. Ultimately, they want to determine earthquake patterns and the magnitude of the potential largest earthquake in the area.

“The earthquake in general was caused by the Pacific Plate being pushed under North America,” Freimüller said. “That Pacific plate is moving about six centimeters per year, which is about two-and-a-half inches per year to the north.”

This process is what eventually resulted in the line of active volcanoes found along the Alaskan Peninsula and the Aleutian Islands. It is also responsible for the largest earthquakes on the planet.

“The reason earthquakes happen is because, for a long time, the contact between two plates was stuck together by friction, just as if you had a heavy object trying to pull it across a carpet,” Freymueller said. “There’s a lot of frictional force that would resist movement.”

Massive earthquakes are caused by a large contact patch sticking together due to friction. When an earthquake occurs, this friction is broken, and there is a sudden movement.

“We’re trying to learn some things that are specific to the region as well as some things that generally correlate with how these types of faults behave,” he said.

With this earthquake, one of the questions Freymueller and his team are looking at is why it didn’t generate so many tsunamis.

“Tsunamis are usually generated when there is some kind of displacement on the sea floor, so part of the sea floor is rising or falling,” he said. “This is actually caused by the motion of the earthquake, not the seismic waves, not the vibration, but the position associated with the earthquake.”

This earthquake did not result in significant displacement of the seafloor because the earthquake stopped at a relatively deep depth.

“It was probably within 20 kilometers below the surface, about 12 miles below the surface,” Freimüller said. “Why did he stop there? Why didn’t he continue to the surface? That’s what we don’t know the answer to yet.”

Photo provided by Jeffrey Fremweiler.

If an earthquake of shallow depth occurred in the same location, it would likely trigger a large tsunami that could damage even the West Coast of the United States.

“It’s not just a local concern, but it could become a concern for Hawaii, the West Coast, and so forth,” Freymueller said. “We also want to better understand what the risks are, what the risks are, and be able to provide that kind of information so that some kind of risk assessment can be done.”

These large earthquakes are a major redistribution of forces within the Earth. When the interface gets stuck, the top plate, which will be North America in this case, is compressed and pushed back. The process is similar to spring loading.

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Freimüller said, “The interface is compressed, and when an earthquake occurs, it springs back. This results in a very large redistribution of internal forces within the Earth, and the Earth actually responds to this change. We don’t just see an earthquake, but we see the earthquake and what happens after it.”

Starting next year, there will be about six new research sites off the coast of Alaska. It will be a few years before Freymueller and his team get enough data from those sites to do anything with it, but the prospects and enthusiasm are promising.

“You can’t miss these opportunities,” he said.

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