Yukon earthquake reveals hidden fault beneath glaciers

A magnitude 7.0 earthquake on Dec. 6 near the Alaska–Yukon border exposed a fault beneath glaciers, prompting the Yukon Geological Survey to carry out helicopter reconnaissance and field mapping. Scientists say the event provides direct evidence for a decades-old hypothesis about fault connections in a complex plate boundary region.

A helicopter team from the Yukon Geological Survey is surveying a remote mountain area in southwest Yukon after a magnitude 7.0 earthquake on Dec. 6 near the Alaska–Yukon border. The quake appears to have exposed a fault beneath glaciers and has drawn attention because the region sits where large plate boundary systems intersect at near right angles. Field teams have been looking for avalanches, landslides and surface evidence of the rupture to trace how the earth shook. Scientists say the event offers a rare chance to observe a connection that had been hypothesized for decades. Key facts: - The earthquake occurred at 12:41 p.m. local time on Dec. 6 and was reported as magnitude 7.0. - Shaking was felt most strongly in Burwash Landing and Haines Junction, and as far away as Whitehorse, about 250 kilometres from the epicentre. - Yukon Geological Survey teams carried out reconnaissance in December by helicopter to search slopes for landslides, avalanches and fault exposure beneath glaciers. - Researchers say the quake has revealed a previously hypothesized fault and offers new data on how plate boundaries and interior faults connect in this complex region. - Aftershocks are ongoing and scientists around the world are investigating the event; some researchers estimate the rupture may have been on the order of 50 to 100 kilometres. Summary: Scientists say the earthquake has provided direct field evidence of a fault beneath glacial terrain and will help researchers study how deformation and mountain-building are occurring in the area. Teams will continue mapping and analysing the affected slopes to document fault traces and aftershock activity, with further research expected to refine understanding of regional seismic hazards.