On University of Southern California Dornsife Week: Can watching earthquakes unfold lead us to a new path for prediction in the future?

Sylvain Barbot, associate professor of earth sciences, looks into this.

Dr. Sylvain Barbot studied earthquake physics and tectonic geodesy at the Institut de Physique du Globe de Paris, the Institute of Geophysics and Planetary Physics at the Scripps Institution of Oceanography (University of California at San Diego). As a postdoc, he studied at the California Institute of Technology. Dr. Barbot was a Nanyang Assistant Professor and National Research Fellow at the Earth Observatory of Singapore and the Asian School of the Environment. He is now an Associate Professor at the University of Southern California where he conducts research on the physics of friction, fault dynamics, and lithospheric deformation during the seismic cycle.

Watching Earthquakes Unfold: A New Path to Prediction

Imagine what happens when two rough surfaces slide past each other — whether it is rubber on the road or tectonic plates along a fault line. They actually don’t touch completely. Instead, they connect at scattered microscopic points.

My colleague and I developed a theory to explain how those tiny contacts control the frictional resistance. And it may hold the key to understanding when and how earthquakes strike.

For decades, earthquake models have relied on “rate-and-state” friction laws — formulas describing how friction changes with sliding velocity and history of deformation. While effective, they don’t show what’s physically happening at the fault. Our model now does.

We used transparent materials, high-speed cameras, and LED light to capture how these connections evolve, matching them to changes in the light transmitted across the fault. This allowed us to observe the buildup of contact points along the fault and their eventual rupture that heralds an imminent earthquake.

About 30% of contact points disappear within milliseconds during a rupture, but they reform slowly over time. This cycle of formation and destruction of contact points explains how faults store and release stress during the seismic cycle.

We found that these microscopic contacts behave just like a mathematical variable used in earthquake simulations since the 70s, providing a physical explanation for a core assumption in earthquake science.

With this new understanding, we can simulate laboratory earthquakes. The relationship we predict between rupture speed and fracture energy — the energy required to break through a fault — also aligns with linear elastic fracture mechanics, a well-established theory that describes how cracks grow in solids.

If we can monitor these contact properties on natural faults, we may detect earthquakes before seismic waves radiate — opening new possibilities for early warning.

Read More:

[USC Today] – Lighting a new way to predict earthquakes

[PNAS] – Evolution of the real area of contact during laboratory earthquakes

Earthquake Physics

The post Sylvain Barbot, University of Southern California Dornsife – Watching Earthquakes Unfold: A New Path to Prediction appeared first on The Academic Minute.