IOWA CITY — Only seven minutes after a magnitude 7.0 earthquake began shaking Alaska just north of Anchorage on Friday, reverberating seismic waves started to arrive in Iowa.
A seismometer in Trowbridge Hall on the University of Iowa campus began registering the minute movements of just fractions of a millimeter at 11:37 a.m. — shortly after the 11:30 earthquake began rocking Alaska 3,461 miles away.
For Iowans on the street, the shaking would have been imperceptible, according to William Barnhart, UI assistant professor in earth and environmental science.
“But whenever you get earthquakes this large, it triggers waves that will pass around the earth,” Barnhart said. “And we can record those here.”
For an hour and 15 minutes after their arrival, Barnhart reported watching waves echo through Iowa via the UI’s relatively new seismometer, providing geology students the chance to study geological events in real time.
“We can learn lots of different things,” he said of the opportunities bigger earthquakes provide. “When you watch these waves rolling in to Iowa in real time, that’s a neat opportunity to talk about earthquakes and tsunamis and seismic waves propagating through the earth.”
The Alaskan earthquake on Friday, with its epicenter about eight miles north of Anchorage, for a time triggered a tsunami warning that was canceled several hours later. Local media reported widespread damage, with videos on social media showing students sheltering under desks, shattered windows and glass, grocery stores in disarray, and evening buckled streets and collapsed roadways.
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In the coming days, Barnhart and his colleagues and students will analyze the UI seismometer data to try and better understand where and why this earthquake occurred.
“We can then use that information to better understand the hazards associated with these earthquakes,” Barnhart said.
The region is no stranger to earthquakes, though, as Alaska sits on the northern edge of the “ring of fire,” a massive geologically-active zone circling the Pacific Ocean known for producing earthquakes and inciting volcanic eruptions.
Its geological complexity differs from California, where tectonic plates are rubbing up against one another. In Alaska, rather, plates are stacked on top of each other, and one is diving down beneath the other, according to Barnhart, who said events like this week’s earthquake can only enhance geologists’ knowledge.
“Our best understanding is that as one dives down, it’s bending,” he said. “And as it bends down, faults can slip and produce earthquakes.”
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