CHARLOTTE, N.C. - There have been four small earthquakes in the area in the past week.
In Alaska, a possible tsunami warning was issued Tuesday after a 7.9 earthquake magnitude struck.
The local earthquakes may have triggered the Alaskan earthquake.
"We're a sphere, so you can't move one part of the sphere without moving the other part,” UNC-Charlotte geology professor Martha Cary Eppes said.
Scientists track every earthquake across the globe and they're seeing the numbers increase.
They expect that trend to continue.
Eppes said it may be because the speed of the Earth's rotation is changing.
“Because of it slowing down or speeding up, the actual diameter of the Earth changes through time,” Eppes said.
That causes a lot of momentum within the rocks and cracks underground.
The Carolinas have plenty of those cracks, known as faults -- like the Brevard Zone or the Eastern Piedmont System.
The frequency of the earthquakes has scientists puzzled whether it's the cracks or the Earth's rotation causing the earthquakes.
Researchers at UNCC are studying the Catawba River for answers.
Long ago, this river flowed hundreds of feet higher because of earthquakes.
The river receding left behind a lot of ancient floodplains and by figuring out how they formed, the researchers may be able to get a better idea of what's happening now.
"The only way to do that is to look at the dirt and the rocks and that's what we're trying to do with the Catawba," Eppes said.
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