Geophysics seminar: Chris Marone "Earthscope Distinguished lecture" (Penn State) "The Mechanics of Slow Earthquakes and the Spectrum of Fault Slip Behaviors"


 
11/02/2018 - 3:00pm to 4:30pm
Location: 
Hubbs hall 4500
Event Description: 

Talk Abstract

Earthquake science is in the midst of a revolution. Our understanding of tectonic faulting has been shaken to the core by the discoveries of seismic tremor, low frequency earthquakes, slow slip events, and other modes of fault slip that were thought to be non-existent and theoretically impossible only a few years ago. Despite the growing number of observations of slow earthquakes and the fact that they can trigger catastrophic large earthquakes their origin remains unresolved. Basic questions remain regarding how slow ruptures can propagate quasi-dynamically, at speeds far below the Rayleigh wave speed, and how tectonic faults can host both slow slip and dynamic earthquake rupture. In this talk I focus on recent results showing that we can reproduce the complete spectrum of fault slip modes in the lab, ranging from stick-slip to creep-slip. The lab results correspond to fault behaviors ranging from elastodynamic rupture to low frequency earthquakes and aseismic fault creep. I also discuss our work on the evolution of elastic wave speed during the laboratory seismic cycle, which shows precursory changes of wave speed prior to both slow and fast lab earthquakes. Our results suggest that slow earthquakes and transient fault slip behaviors can arise from the same governing frictional dynamics as ordinary earthquakes. The mechanics of slow slip in the lab result from fault creep prior to failure and transient frictional strengthening during nucleation of dynamic instability. These processes could act in concert with other mechanisms that have been proposed for slow earthquakes, including fault zone dilatancy, which may help explain the broad range of geologic environments where slow earthquakes have been observed.

For more information on this event, contact: 
Francesca Silverii
Event Calendar: 
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