A recent study conducted by the University of Victoria (UVic) has revealed alarming signs of seismic activity in the Tintina fault, a major geological feature in Canada’s Yukon Territory. Long considered dormant, this fault stretches approximately 1,000 kilometers across northwestern Canada and has a history of lateral shifts totaling 450 kilometers over millions of years.
For over 40 million years, scientists believed that the Tintina fault had remained inactive. However, advancements in technology, including topographic imaging from satellites, aircraft, and drones, have enabled researchers to identify a 130-kilometer section of the fault near Dawson City. This section shows evidence of multiple large earthquakes during the Quaternary Period, which spans the last 2.6 million years. These findings indicate that the fault may still be active, posing a significant risk for future seismic events.
“In the past two decades, we’ve observed a few minor earthquakes, with magnitudes ranging from 3 to 4, along the Tintina fault,” explains Theron Finley, a recent UVic PhD graduate and lead author of the study published in Geophysical Research Letters. “However, these occurrences did not suggest the fault was capable of larger ruptures. The availability of high-resolution data prompted us to revisit the fault to search for evidence of prehistoric earthquakes.”
Seismic hazard assessments across Canada typically rely on historical earthquake records, including Indigenous oral histories, archived documents, and real-time readings from modern seismic networks. However, these records only extend a few hundred years into the past, while major faults can remain silent for thousands of years. This gap means that significant seismic risks may go undetected without careful geological investigation.
When significant earthquakes occur, they often create a feature in the landscape known as a fault scarp. These linear features can last for thousands of years, measuring tens to hundreds of kilometers in length but only a few meters wide and tall. Detecting them in heavily forested regions like Canada requires high-resolution topographic data. The research team, consisting of experts from UVic, the Geological Survey of Canada, and the University of Alberta, utilized ArcticDEM satellite data and lidar surveys to identify several fault scarps near Dawson City.
Crucially, they found glacial landforms that are 2.6 million years old offset laterally by 1,000 meters across the fault scarp. Additionally, landforms dating back 132,000 years showed offsets of 75 meters. These findings confirm that the Tintina fault has experienced multiple earthquakes throughout the Quaternary period, likely moving several meters with each event. Interestingly, landforms that are 12,000 years old displayed no offsets, indicating that no significant ruptures have occurred since that time.
The Tintina fault continues to accumulate strain at a rate of 0.2 to 0.8 millimeters per year, raising concerns about a future earthquake threat. “Our research suggests that future earthquakes on the Tintina fault could exceed magnitude 7.5,” states Finley. “Based on our findings, we believe the fault is at a relatively late stage of its seismic cycle, having accrued a slip deficit of six meters over the last 12,000 years. The release of this strain could result in a significant earthquake.”
An earthquake of magnitude 7.5 or greater would likely cause severe shaking in Dawson City and could threaten nearby highways and mining infrastructure. Additionally, the region is vulnerable to landslides, which could be triggered by seismic activity. Recent observations of the Moosehide landslide north of Dawson City and the Sunnydale landslide across the Yukon River indicate ongoing instability in the area.
The National Seismic Hazard Model (NSHM) of Canada acknowledges the potential for large earthquakes in central Yukon Territory; however, the Tintina fault is not currently listed as an active seismogenic fault source. The recent findings from the UVic research team will be integrated into the NSHM, which plays a crucial role in shaping seismic building codes and engineering standards aimed at protecting lives and infrastructure. Moreover, this information will be shared with local governments and emergency management agencies to enhance earthquake preparedness in their communities.
For more detailed insights, refer to the study titled “Large Surface-Rupturing Earthquakes and a >12 kyr, Open Interseismic Interval on the Tintina Fault, Yukon” by Theron Finley and colleagues, published on July 15, 2025, in Geophysical Research Letters.
