Residents of the upper Kuskokwim River community of McGrath and as far downriver as Kalskag were caught off guard late on the evening of Jan. 29 when a rare magnitude 5.2 earthquake shook the region.
No significant damage had been reported as of the evening of Jan. 30.
According to the Alaska Earthquake Center, one resident of Takotna, a tiny community just 9 miles from the epicenter, described the quake as 50 seconds of shaking that felt like “waves in my walls.”
Roughly 150 miles southwest, Aniak resident Shandila Adkins said that she also felt the wave effect.
"It happened around 7:40 [p.m.], and I was watching TV, and it surprised me. It felt like a boat was passing by. It was not a jolt. It was like waves coming around this house, no damage. It was just sudden waves," Adkins said.
Adkins, a lifelong resident of Aniak, said that she can’t recall ever experiencing an earthquake in her hometown. She said that the Jan. 29 quake was nothing like those she has experienced in Anchorage.
"I think I was just in shock and didn't know what to do. I mean, if I was in Anchorage I’d know what to do, but out here it's foreign to me," Adkins said.
Elisabeth Nadin, communications manager for the Alaska Earthquake Center, said that the quake was roughly 5 miles deep and centered directly on a section of a fault line called the Iditarod-Nixon fault that hasn’t seen significant seismic activity in nearly a century.
"My understanding is this section of the fault has not ruptured since 1935. That was the last documented earthquake on this particular part of the fault," Nadin said.
That 1935 earthquake was magnitude 6.2. Earthquakes are measured on a scale along which each whole number represents a tenfold increase in how much the ground shakes.
In 1904, scientists believe a magnitude 7.3 quake – roughly ten times stronger than the 1935 quake – rocked the northeastern end of the same Iditarod-Nixon fault, a weak spot in the Earth’s crust several hundred miles long that runs diagonally from Aniak up and through McGrath.
The most recent earthquake of comparable size in the area was a magnitude 5.4 earthquake in 1989 centered just south of McGrath.
In April 2024, a magnitude 4.1 earthquake south of the lower Yukon River community of Holy Cross also shook residents of middle Kuskokwim River communities.
The Jan. 29 earthquake was followed several hours later by two nearby aftershocks, registering magnitude 3.5 and 3.2.
