ALASKA — A linear pattern of approximately 3,000 previously undetected tiny earthquakes was discovered clustered under the Denali Fault in Alaska. The discovery reveals the edge of the Yakutat microplate subducting under the North American Plate, according to a study published on June 4, 2026, in The Seismic Record.

The earthquakes form a straight line running northwest to southeast for 155 miles (250 kilometers). This pattern aligns with a series of small volcanic cones and rock-type changes observed in the deep subsurface. Researchers installed seven new seismometers south of the Denali Fault to facilitate the study of the region. The location of the microplate's edge also aligns with the initiation point of the magnitude 7.9 Denali earthquake that occurred in 2002.

The Yakutat microplate is an ocean plateau formed by volcanoes tens of millions of years ago. It is thicker and more buoyant than the surrounding Pacific oceanic crust, and its subduction pushes up the Alaska Range, which includes Denali.

Meghan Miller, a seismologist at the Australian National University and the study's first author, stated that identifying the microplate's subsurface location has aided in understanding the region's tectonics. "Being able to identify where the Yakutat microplate is in the subsurface has helped us understand the tectonics," Miller said. "What we were postulating is that the edge of the Yakutat plate is influencing all these different types of processes."

Why It Matters

This discovery provides insights into the geological structure of Alaska, particularly the behavior of the Yakutat microplate. The subduction of this microplate is a factor in the formation of the Alaska Range and its influence extends to various subterranean processes, including seismic activity.