UC Berkeley

Here I present results from a collection of three papers that document the response of deep non-volcanic tremor and constituent low-frequency earthquakes to stress perturbations from the Earth tides. Variations in the seismicity rate are used to constrain the rheology of the deep San Andreas fault and to infer \emph{in situ} conditions in the deep crust. I find that effective stresses orders of magnitude smaller than expected can explain observed response of non-volcanic tremor and low-frequency earthquakes to primarily small, tidally-induced shear stresses. Low effective stress also provides a mechanism for frictional slip to occur in environments where elevated temperature and pressure conditions are thought to make ductile creep processes the favored mode of deformation.