The Eastern California shear zone (ECSZ) is a major element of the Pacific-North America plate boundary that has been extensively studied, yet displays unexplained kinematic traits. The shear zone is wide and consists of discontinuous, irregular strike-slip faults, rather than a well-integrated fault zone. Individual faults in the ESCZ are more closely spaced and geometrically complex than other comparable secondary zones of strike-slip, such as to the west of the southern San Andreas fault (SAF), to the east of the SAF in northern California, and in the Marlborough fault system of New Zealand. The geometric complexity of faults in the ECSZ also results in complex stepovers and strain transfer zones, which impact rupture pattern and strain partitioning in unknown ways. Kinematic models of the spatiotemporal evolution and rotation of the ECSZ exist, yet these have not been thoroughly tested (Dixon & Xie, 2018;Dokka & Travis, 1990a, 1990bNur et al., 1993). There is thus need for systematic study of the kinematics of faulting in the ECSZ.The ECSZ is also an ideal setting to investigate the influence of geometry on fault processes. The geometry and kinematics of faults and fault networks are relevant for both our understanding of their mechanical behavior and for seismic hazards. Geometric complexity on faults is a form of roughness, which can influence rupture dimension and style, fault strength and stress field, slip distribution and heterogeneity during rupture, and earthquake recurrence (