Residents in and around Takotna, Alaska were surprised on the evening of January 29, 2025 by significant shaking from a magnitude 5.2 earthquake. Alaska Earthquake Center analysts placed the earthquakes just nine miles west of Takotna and at a depth of five miles (9 km) on the Iditarod-Nixon Fork Fault. Despite being classified as active, this fault has not produced significant seismicity since 1935.

Takotna resident Clinton Goods spoke to just about everyone in town after the earthquake and did not hear of any damage, but he said, “It shook everybody’s house pretty good.” He described the shaking as lasting about 50 seconds, and, “I thought that if it lasted much longer that my walls would crash in. It was like waves in my walls.”

The Alaska Earthquake Center auto-detection system initially reported more than one event. Analysts were able to quickly determine that the second was a rare occurrence of a “phantom earthquake,” an auto-populated alternative best-fit solution to the data available from sparse seismic stations in this part of Alaska.

Alaska is no stranger to earthquakes, but some parts of the state tend to shake more, and more frequently, than others. University of Alaska Fairbanks seismologist Carl Tape has been tracking historical earthquake activity in this area for years. In 2017, he published a paper speculating that two significant earthquakes, recorded globally, happened on the northeasternmost end of the Iditarod-Nixon Fork Fault. One was a magnitude 7.3 in 1904, traced back to this location from seismic waves recorded on instruments outside of Alaska. The state didn’t have any seismic stations at the time. The other was a magnitude 6.2 in 1935.

“A magnitude 5 anywhere in Interior Alaska is significant,” said Tape. He adds that this event, directly on the Iditarod-Nixon Fork Fault, is exceptionally significant. “We just confirmed that this fault truly is active, and is a right-lateral strike-slip fault.”

Mimicking the style and orientation of the Denali Fault, the Iditarod-Nixon Fork Fault shifts horizontally when it ruptures. Just like the western Denali Fault, it accommodates the rotation and extrusion of southcentral Alaska, driven by the subduction of the Pacific plate, according to Barrett Salisbury, the Earthquake and Tsunami Hazards Program manager at the Alaska Division of Geological & Geophysical Surveys. He points out that large earthquakes this far north are rare because fault slip rates decrease farther from the plate boundary.

Seismic waves from this event were reported as felt as far as 250 miles away, in Anchorage.

Similar to Takotna, residents of McGrath were surprised by the shaking. “It was the first earthquake I can recall feeling in my life,” said Paul Walker, host of the McGrath radio station KSKO. He thought the shaking lasted about 30 seconds, or “long enough to have a ‘holy s***’ moment, but not long enough to think the world was over,” he said. Walker heard from many people throughout McGrath that the earthquake visibly shook their homes. He got a call from someone in Shageluk, about 150 miles away, whose couch shook under her.

The main shock was followed a couple of hours later by two aftershocks, a magnitude 3.5 at 10 pm, and a magnitude 3.2 at 10:47 pm. According to the U.S. Geological Survey aftershock forecast, there is a 30 percent chance of a magnitude 3 or greater aftershock in the coming week.