Fault slip, fault mapping, and age constrains along the North Olympic fault zone, Washington

The SCF is a ≥14 km-long northwest-striking, subvertical, dextral strike-slip fault with a subordinate dip-slip component. Laterally offset debris flow channels cut into late-Pleistocene and younger surfaces show dextral slip of 4.0–24.5 m and dip slip of 0.7–6.5 m.

Reevaluation of fault slip on the adjacent Lake Creek Boundary Creek fault (LCBCF) shows similar dextral (4.5–29.7 m) and dip slip (0.8–4.6 m). A deglacial age of 14 ka paired with the largest – and presumably oldest – slip measurements produces a minimum dextral slip rate of 1.3–2.3 mm/yr and dip-slip rate of 0.05–0.5 mm/yr. Similarities in kinematics, slip rate, and earthquake timing between the SCF and LCBCF suggest these faults represent one continuous geologic structure, the North Olympic fault zone.