Canadian researchers have uncovered new evidence that a long-dormant fault line in the Yukon Territory may not be as inactive as once believed. According to scientists from the University of Victoria (UVic), the Tintina fault, a 620-mile-long fracture running northwest across the region, could still generate a powerful earthquake exceeding magnitude 7.5.
For decades, geologists assumed the Tintina fault had been dormant for at least 40 million years. However, high-resolution mapping using satellite, drone, and aircraft-based lidar data has painted a very different picture.
Lead author Theron Finley, PhD, a surficial geologist at UVic, explained: “The expanding availability of high-resolution data prompted us to re-examine the fault, looking for evidence of prehistoric earthquakes in the landscape.”
The team zeroed in on an 80-mile section near Dawson City, which shows clear displacement in relatively young landforms, evidence of geologic movement in the not-so-distant past.
The study revealed that the Tintina fault has slipped multiple times over the past 2.6 million years, during the Quaternary period. Some glacial features have shifted by as much as 3,280 feet, while others dating back roughly 132,000 years show offsets of about 246 feet.
Interestingly, younger formations around 12,000 years old remain untouched, implying no major ruptures since then. Still, the fault is accumulating strain at a steady pace up to 0.03 inches per year.
As Finley noted: “Over the past couple of decades there have been a few small earthquakes of magnitude three to four detected along the Tintina fault, but nothing to suggest it is capable of large ruptures.”
Despite the lack of recent large quakes, scientists warn that strain has been building over thousands of years. Finley cautioned: “We determined that future earthquakes on the Tintina fault could exceed magnitude 7.5.”
He estimates that nearly 20 feet of strain has accumulated over the last 12,000 years. If released in a single event, the resulting earthquake could devastate Dawson City, disrupt highways, and threaten mining operations across the Yukon.
Currently, Canada’s National Seismic Hazard Model does not recognize the Tintina fault as a source of large earthquakes.
These new findings are published in Geophysical Research Letters.