Experimentally determined values of fault frictional strength and stability can be used to better understand the boundary conditions necessary to sustain a variety of tectonic slip modes including elastodynamic ruptures and slow slip. We utilized samples acquired during International Ocean Discovery Program Expedition 375 to experimentally constrain the frictional behavior of inputs to the shallow plate boundary at the northern Hikurangi margin. Current and future work is focused on the Wasatch Fault Zone in Utah and the Japan Trench.