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FM: Physical Fault Models: Using Rubber Earthquakes to Understand Seismological Stress Drops and Earthquake Nucleation

Category: Webinars

Will Steinhardt, UC Santa Cruz

Many geophysical systems, including faults, ice sheets, and hill slopes, are predominantly stable, but become unstable catastrophically, with severe societal consequences when they do.  The behavior of these systems is often difficult to predict because they involve extreme spatial and temporal scales, accumulating stresses over decades or centuries, but nucleating failure processes in fractions of second, which start at the micron scale but can lead to kilometers of deformation.  To explore these systems, I utilize techniques from applied physics to build scaled-down experiments that behave like “physical models”, where a wide range of system properties can be actively tuned to and otherwise impossible observations made.  I will describe a scaled, transparent laboratory fault that shares many similarities to traditional biaxial friction experiments, but studies slip events on a fault made out of a transparent rubber instead of rocks.  While rubber may seem like an odd material for studying faults, the measured events display the scaling behaviors of natural earthquakes and slow slip events, and using transparent rubber offers a number of unique experimental advantages and possibilities, including: direct imaging of slip at the frictional interface, active control over normal stress heterogeneity, and ruptures that are fully contained within the edges of the fault area.  I will show that slow slip events in our system follow earthquake-like scaling, and demonstrate how finite fault effects alter the stress drop of events. In addition, I will discuss preliminary results from this system on the earthquake nucleation process.

Short Biography Will Steinhardt earned his BS in 2011 from Caltech and PhD in 2020 from Harvard. He is now  a postdoctoral researcher at UC Santa Cruz working with Emily Brodsky.  His research involves developing scaled-down laboratory systems to study unstable geophysical systems like faults, hillslopes, and ice sheets, and developing and utilizing multi-dimensional field and laboratory measurements to better connect these analog systems to nature. He is especially interested in exploring the role of heterogeneity in determining the dynamics, complexity and roughness of both faults and fractures, as well as problems related to damage, wear, and granular dynamics.

When: Friday 03 March, 2023, 1:00 pm - 2:00 pm PST
Where: zoom
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