To slip or not to slip: The geology, petrology, and rheology of deep slow slip in subduction zones

Subduction zones host some of the deadliest geologic hazards on Earth: megathrust earthquakes, tsunamis, volcanic eruptions, and co-seismic landslides. How, when, and why subduction zones creep aseismically or slip catastrophically as an earthquake are fundamental questions that are at the forefront of subduction zone science. Recent observations from heavily instrumented subduction margins reveal enigmatic behavior downdip of the locked seismogenic zone, including Episodic Tremor and Slip (ETS) events. In some cases, ETS events have preceded, and potentially triggered, large megathrust earthquakes and can release the same amount of energy as a Mw 6-7 earthquake over several weeks to months. Today, more than 20 years after the discovery of ETS, we still lack a full mechanistic understanding of what causes them. In this talk, I will present a combination of field observations, stable isotope geochemistry, and petrologic and rheological modeling to establish constraints on the mechanisms that produce ETS. I will argue for the vital role thatfluids, lithologically diverse zones, and metamorphic and metasomatic reactions play in leading to these events.

About this Series:

The Department Lecture Series at EAPS at MIT is a series of Weekly talks given by leading thinkers in the areas of geology, geophysics, geobiology, geochemistry, atmospheric science, oceanography, climatology, and planetary science. For more information and Zoom password please contact David Wright: djwright@mit.edu