A recent study on earthquakes led by Sylvain Barbot, an associate professor of earth sciences, revealed significant flaws in longstanding theories about their characteristics. Old theories made several faulty assumptions about the nature of friction concerning earthquakes. One posited that friction will be independent of temperature at certain sliding velocities of rocks. Another assumed that friction must overcome an energy barrier based on time and stress, which isn’t observed in many ways.  

The study, which was published in August by the Proceedings of the National Academy of Sciences, found that contrary to traditional assumptions about friction in earthquakes, changes in friction can be attributed to transitions between different types of rock deformation. This contrasts longstanding theories which suggest that temperature has the most influence on friction in fault zones.

Barbot had been skeptical of traditional models for much of his career and hoped to provide evidence to disprove them.

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“I’ve seen ideas and concepts used to understand earthquakes for 20 years or so that I thought were obviously wrong and had fatal flaws, and yet they were very popular and widely used,” Barbot said. “I felt we needed as a community to spend our time and energy in a productive direction, so we needed to abandon all ideas that don’t work very well.”

He said the old theory of earthquakes fails to provide insight into key phenomena such as the friction coefficient, which describes the relationship between friction and pressure, preventing the theories from being useful.

“I consider this study as community service to put my finger on problems of previous theories and first show how we know it’s wrong … and two, what makes it wrong,” Barbot said. “I’m thinking about generations of grad students and scientists who are taught this.” 

Undergraduate students who currently study geological sciences are faced with the challenge of learning information that can often be dubious, but as Barbot said, it’s common to assume that longstanding theories are accurate.

“I haven’t really dug into the deep part of the subjects, so I will say I won’t question too much about the concepts I’m learning, especially those that have been established for a long time,” said Mengshi Liu, a sophomore majoring in geological sciences.

Ailani Bonilla, a senior majoring in geological sciences, is interested in studying the chemistry of the mantle, making it important for her to understand the processes that take place in subduction zones. But when it comes to scientific research, it isn’t always clear cut.

“There’s so much ambiguity. There’s no black and white answer to what you’re seeing, and there are so many different explanations … and you see scientists argue about it all the time in the papers — one contradicts another and there’s never a straight answer,” Bonilla said.

When it comes to scientific discovery, Barbot said there is a prevalence of “intellectual viscosity” — the reluctance of people to embrace new theories and forget about old ones. He said such reluctance is beneficial in that new ideas need time to be considered before they can be accepted. After releasing the study, Barbot encountered many people who were skeptical of his new propositions, despite the data and facts that substantiated his findings.

“It’s a natural reaction, and I’ve generally found younger scientists to be more open-minded about this,” Barbot said.

By researching earthquakes, Barbot hopes to progress toward uncovering how to predict them. If he cannot do it, he hopes he will at least help the next generation in doing so.

“We all want to better understand earthquakes to the point that we may even predict them and mitigate their devastating effects,” Barbot said.

The findings and implications of this study are also relevant to people outside the scientific community. Bonilla said people who live in places where earthquakes occur relatively frequently should care about the issue.

“If you live in California, where there’s an active fault line, you’re experiencing earthquakes all the time. Whether you feel it or not, they’re always happening,” Bonilla said.

Barbot’s goal in releasing this discovery was not only to substantiate his ideas that common earthquake theories were flawed, but also to educate people, foster conversation in the community and convince people to change their point of view, he said.

“Right now it seems a bit theoretical … but really, it’s an important step toward earthquake prediction. If this is at all possible, you need people to care about this if you want to make progress toward that goal,” Barbot said.