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Deep geological scars influence modern earthquakes

"This is a potentially major revision to the fundamental idea of plate tectonics," earth scientist Philip Heron said.

By
Brooks Hays
A new map published in the journal Nature Communications shows where ancient plate boundaries may continue to influence the structure and behavior of the earth's crust in the interior of tectonic plates. Photo by Russell Pysklywec/Philip Heron/Randell Stephenson
A new map published in the journal Nature Communications shows where ancient plate boundaries may continue to influence the structure and behavior of the earth's crust in the interior of tectonic plates. Photo by Russell Pysklywec/Philip Heron/Randell Stephenson

TORONTO, June 10 (UPI) -- Most inquiries into the nature of earthquakes look at interactions between tectonic plates. But new research shows the scars of ancient geologic events can influence modern geologic processes, including earthquakes.

Computer models designed by a team of scientists from Canada and Scotland suggests there is life after death for ancient fault lines. Researchers say these ancient plate boundaries can come back to life, so to speak, and trigger changes in the structure and behavior of the earth's crust and upper-mantle in the interiors of continental plates.

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"This is a potentially major revision to the fundamental idea of plate tectonics," Philip Heron, an earth scientist and postdoctoral fellow at the University of Toronto, said in a news release.

Heron is the lead author of a new paper on the research, published in the journal Nature Communications. The study features a map detailing geologic sites across the globe that may continue to be influenced by ancient geologic events.

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"It's based on the familiar global tectonic map that is taught starting in elementary school," explained Russell Pysklywec, chairman of Toronto's earth sciences department. "What our models redefine and show on the map are dormant, hidden, ancient plate boundaries that could also be enduring or 'perennial' sites of past and active plate tectonic activity."

Though the pressure and forces exerted on the Earth's mantle and crust are strongest near the plate boundaries, the crust within the interior of each plate also flows, breaks and folds in response to geologic forces.

"Most of the really big plate tectonic activity happens on the plate boundaries, like when India rammed into Asia to create the Himalayas or how the Atlantic opened to split North America from Europe," says Heron. "But there are lots of things we couldn't explain, like seismic activity and mountain-building away from plate boundaries in continent interiors."

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Researchers designed a computer model to analyze these smaller-scale stresses and strains. They found deeper-lying structures in the mantle have an outsized influence on the patterns and behaviors exhibited by the interior crust.

Scientists say these deeper formations have been mostly ignored by scientists in favor of shallower crustal structures. But Heron and Pysklywec believe their latest findings will change that.

"Future exploration of what lies in the mantle beneath the crust may lead to further such discoveries on how our planet works, generating a greater understanding of how the past may affect our geologic future," concluded Heron.

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