Given the rigidity of tectonic plates, most of their relative motion is accommodated at the boundaries between plates. At shallow depths the plate boundary is brittle, and the long-term loading and episodic release of the earthquake cycle dominates this relative plate motion. Dr. Frank will present recent work that explores the loading phase of the earthquake cycle and specifically addresses the role of slow slip, deeper fault motion that is too slow to radiate seismic waves. Dr. Frank will show that the rich dynamics of slow slip, as can only be captured through the lens of repetitive tiny seismic events called low-frequency earthquakes, highlights that tectonic loading during the earthquake cycle is unexpectedly jerky and intermittent. These observations suggest that heterogeneous lithology and high pore fluid pressures are key factors in controlling how tectonic motion is accommodated on the deep plate interface, and consequently how stress is transferred updip to the source region of major earthquakes.