A long-overlooked geologic fault in Canada’s remote north may be capable of producing a massive earthquake, according to new research.
The Tintina Fault, stretching about 620 miles (1,000 kilometers) from British Columbia to Alaska, was once thought to be inactive for at least 40 million years. Now scientists say it has a history of large ruptures within the last 2.6 million years and could do so again.
The study, led by researchers at the University of Victoria (UVic) identified an 81-mile (130-km) section of the fault near Dawson City where multiple past quakes have left their mark on the landscape. The team used high-resolution topographic data from satellites, aircraft and drones to detect fault scarps, narrow ridges formed when the ground shifts during an earthquake, that were previously hidden under dense forest and glacial deposits.
“Lidar and satellite data are incredibly important for this kind of work, and have revolutionized the field of paleoseismology,” lead author Theron Finley told Space.com in an email. “There are many other cases in Canada and beyond where previously unrecognized faults have been discovered thanks to this technology.”
Evidence of ancient, powerful earthquakes
By measuring how far landforms have been displaced, scientists pieced together the fault’s recent activity. Glacial features 2.6 million years old have shifted sideways by about 0.62 miles (1 km), while features 132,000 years old are offset by 246 feet (75 meters). Significantly, features just 12,000 years old show no displacement at all.
This long, quiet period is not necessarily good news. Based on tectonic strain rates of about 0.008 to 0.03 inches (0.2 to 0.8 millimeters) per year, researchers estimate the fault has built up about 20 feet (6 meters) of slip deficit since its last major earthquake.
“Though our observations indicate a substantial slip deficit, we don’t yet have a good sense of how frequently large ruptures occur on the Tintina fault,” Finley said. “At this point we can’t really say whether another rupture is likely in the short term, or in thousands of years.”
To gain a better understanding of how often large earthquakes strike the Tintina fault, Finley said they plan to excavate a paleoseismic trench across it. This would allow the team to examine offset sediment layers and date past quakes, providing a clearer picture of the fault’s recurrence rate.
How the fault moves
Click Here to Read the Full Original Article at Latest from Space.com…