by Small leisure vehicle drives the Dempster Highway near Dawson City, Yukon, Canada. Credit – Robert Postma/Design Pics Editorial/Universal Images Group – Getgge Pictures
HIn Canada’s Yukon Territory, a seismic weapon is stretched and aimed at the small community of Dawson City – population 1,600. When a new study in the magazine Geophysical research letters It is correct that the city or one of many others in the region could be shaken by a large earthquake through any moment. The source of danger is a 1000 km formation, which is known as a Tintina fault, which is northwest over the Yukon and ends in Alaska. It has been largely still over in the past 12,000 years, but seems to prepare to celebrate life.
“In the past few decades there have been some small earthquakes with the strength of 3 to 4 along the Tintina, but nothing that indicates that it is great slides,” said Theron Finley, recently doctoral student at the Canadian University of Victoria and the main author of the study. However, this is not the whole story, says Finley. What is close in recent decades and what the geological recording now shows is two different things – and according to the newspaper, Tintina is much more threatening than it seems.
What aroused the interest of Finley and his colleagues is a 130 km long segment of the error that runs near Dawson City. Surface features, which indicates that numerous large earthquakes have occurred in relatively new geological history-in the quaternary period, which runs from 2.6 million to the present day. In order to get a better understanding, the researchers used an existing library of high-resolution images from aircraft, satellites and drones, some of which were recorded by Lidar, the pulsed laser emissions used to create 3D cards from the surface. This enabled them to investigate that the error of the error in unprecedented details – and a number of geological secrets are found that are hidden in sight.
At one point in the Tintina segment, they discovered a fault scarp -or a directed crack in the surface -in which the country was broke and moved around 1,000 m (3,280 feet). This is a clear fingerprint of a long series of earthquakes that occurred according to the computer models of the site about 2.6 million years ago. At another point, they found another Scarp, which was wrongly aligned by a more modest 75 m (250 feet) that they estimate that they were caused by smaller but still considerable quakes about 132,000 years ago. In the past 12,000 years, no evidence of considerable quake has been driven at some point, which means that Tintina was relatively stable in the entire Holocene era, which runs from 11,700 years to the present day.
But for modern people who live in Dawson and elsewhere, this latest period of calm is actually bad news. Just because an error does not cause quake does not mean that it is not in motion. Finley and his colleagues estimate that Tintina moves and accumulates the size of 0.2 mm to 0.8 mm per year. Over the course of 12,000 years, these millimeters add up, and if the stress is suddenly released – which ultimately has to be – the result will not be pretty.
“We have found that future earthquakes in the Tintina fault could exceed size 7.5,” said Finley in an explanation. “Based on the data, we are of the opinion [20 ft] In the past 12,000 years. If this were released, it would cause considerable earthquakes. “
The estimated size of the quake of 7.5 would bring to a size with some of the larger preliminaries of history, including China’s Tangshan event in 1976, which was estimated to have 240,000 to 650,000 lives. And the Haiti quake of 2010, which killed 300,000. The Yukon territory is much sparsely populated than Tangshen or Haiti, which means fewer victims. Nevertheless, there would be very likely deaths together with damage to local highways, mines and other infrastructures. The area is also susceptible to landslides that can be triggered by a quake.
“Our results,” wrote the researchers, “have a significant impact on the seismic danger in the Yukon territory and in neighboring Alaska. If 12,000 years have passed since the last big earthquake, the error can be in an advanced level of the accumulation of stems.”
It is impossible to know exactly when this burden is released – one of the things that make seismology into such a confusing science. The best thing the scientists can do is to warn the locals of the long -term risks and leave them to prepare Go bags, survival kits and evacuation plans. The earth will shake as desired; We can only react.
Corrections, July 30: The original version of this story incorrectly stated the year of the Haitian earthquake. It was in 2010, not in 2020. In addition, this story incorrectly stated how the age of Scarps was determined. The researchers used computer modeling, not the erosion analysis. The article also incorrectly found that individual earthquakes were responsible for the 1000-meter and 75-meter defect. There were several quakes at both locations, not just one at everyone.
Write Jeffrey Kluger at jeffrey.kluger@time.com.
