From: University of Pennsylvania
Published February 22, 2017 12:39 PM

Researchers Gain Insight Into a Physical Phenomenon That Leads to Earthquakes

Scientists have gotten better at predicting where earthquakes will occur, but they’re still in the dark about when they will strike and how devastating they will be.

In the search for clues that will help them better understand earthquakes, scientists at the University of Pennsylvania are studying a phenomenon called ageing. In ageing, the longer that materials are in contact with each other, the more force is required to move them. This resistance is called static friction. The longer something, such as a fault, is sitting still, the more static friction builds up and the stronger the fault gets.

Even when the fault remains still, tectonic motion is still occurring; stress builds up in the fault as the plates shift until finally they shift so much that they exceed the static friction force and begin to slide. Because the fault grew stronger with time, the stress can build up to large levels, and a huge amount of energy is then released in the form of a powerful quake.

“This ageing mechanism is critical in underlying the unstable behavior of faults that lead to earthquakes,” said Robert Carpick, the John Henry Towne Professor and chair of the Department of Mechanical Engineering and Applied Mechanics in Penn’s School of Engineering and Applied Science. “If you didn't have ageing, then the fault would move very easily and so you'd get much smaller earthquakes happening more frequently, or maybe even just smooth motion. Ageing leads to the occurrence of infrequent, large earthquakes that can be devastating.”

Read more at University of Pennsylvania

Photo credit: Ian Kluft

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