A crack stretching more than 620 miles across northwestern Canada could one day cause ‘at least’ a 7.5 magnitude earthquake.
Tintina is a fault line – where two of Earth’s puzzle pieces, tectonic plates, meet – which runs from northeastern British Columbia to central Alaska.
Experts have never worried too much about it, believing it has been asleep for about 40million years.
But researchers have revealed in a new study that an 81-mile-long stretch of the fault line in Yukon has been very much awake for 2.6million years.
The study, published in the Geophysical Research Letters, found that the crack has produced multiple strong tremors between a magnitude of three and four, enough to cause minor damage.
Worryingly, whether the fault could cause an even larger tremor isn’t a question of if; it’s when.
The most active chunk is grumbling about 12 miles from Dawson City, a town home to 1,500 people, University of Victoria researchers found.
Tintina is a right-lateral strike-slip fault, where two chunks of the Earth’s crust slide against each other horizontally.
By looking at how far the landforms have shifted around, scientists pieced together the fault’s recent movements.
And by ‘recent’, we mean geologically recent. One side of the fault slipped about 270 miles during the Eocene period, some 55million years ago.
But the team realised that Tintina is more active than first thought by examining fault scarps, steep slopes and cliffs formed by earthquakes.
These scarps can easily be tens of miles long, but only a few metres wide and tall, making them tricky to see in forested areas like Canada.
The scientists used satellite images and data to identify fault scarps near Dawon City that suggest the last time the fault experienced a major earthquake was at least 12,000 years ago.
Two tectonic grinding on one another causes friction and pressure to build up. Once the force of the plates moving exceeds the friction, they suddenly jolt and release seismic waves that shake the ground, causing a quake.
With 12,000 years of pressure built up, the study warned that Tintina is overdue for a Big One.
Lead author Theron Finley said in a statement: ‘We determined that future earthquakes on the Tintina fault could exceed magnitude 7.5.’
‘Based on the data, we think that the fault may be at a relatively late stage of a seismic cycle.’
A 7.5 magnitude earthquake and the tsunami that followed it killed more than 4,300 people in Indonesia in 2018. While 645 people died after a 7.5 quake shook Noto, a peninsula in northern Japan, last year.
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Finley’s team added that a quake of this scale would rattle Dawson City and could pose a threat to nearby roads and mines.
Dr Jonathan Paul, a senior lecturer from the Department of Earth Sciences at Royal Holloway, University of London, told Metro that Tintina is a ‘spectacular fault not to have been detected before’.
‘It’s like San Andreas, only about six times as long,’ he said, referring to the tension-wracked fault line slicing through California.
‘It’s in a very remote location so, even if there were a huge earthquake, the damage to people’s livelihoods and the local economy is likely to be minimal.’
Dr Paul said that it’s ‘impossible to predict’ when an earthquake might happen, and the one that could happen along Tintina is no exception.
He added: ‘Digging trenches across the fault would also be a prerequisite to understanding whether the fault is likely to move in a single jump, releasing a huge amount of energy all at once (i.e. an earthquake) or whether movement might take the form of a cluster of much smaller ruptures, or even slower creep motion.
Dr Ian Stimpson, a senior lecturer in geophysics at Keele University, similarly said that there’s no suggestion the quake hitting the remote region is ‘imminent’.
‘If I were Canadian, I would be more concerned about a magnitude seven-plus earthquake from the Cascadia subduction zone beneath Vancouver, a region with 2.7 million people living there,’ he told Metro.
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