EEPS Colloquium: Cailey Condit

Deep slow earthquakes (often called slow slip events) occur along the megathrust fault in many subduction zones, release as much energy as an Mw6-7 earthquake, and can trigger destructive megathrust earthquakes. However, we don’t actually know what slow earthquakes are; this makes it nearly impossible to incorporate them into our framework of subduction seismicity. Geophysical and geologic observations of the megathrust where slow earthquakes occur show us that it is a chemically dynamic and fluid-rich zone. These rocks are metamorphosing as they are deforming, yet little work has been done to map out the feedbacks between these deeply interconnected sets of processes, and the way these feedbacks may lead to slow earthquake formation. In this talk, I will present a mix of observations from the exhumed rock record, experimental data, and geodynamic, rheological, and petrologic modelling to constrain the chemo-mechanical behavior of the slow slip source region. I’ll then suggest a holistic model for how slow earthquakes form and why we must consider chemical transformations when we study processes happening in metamorphosing and deforming rocks (i.e. much of the lithosphere). 

Photo is from Sifnos Island, Greece.