Transient strain accumulation and fault interaction in the Eastern California shear zone

Satellite synthetic aperture radar interferometry reveals transient strain accumulation along the Blackwater Little Lake fault system within the Eastern California shear zone. The surface strain map obtained by averaging eight years (1992 2000) of Earth Resource Satellite (ERS) radar data shows a 120-km-long, 20-km- wide zone of concentrated shear between the southern end of the 1872 Owens Valley earthquake surface break and the northern end of the 1992 Landers earthquake surface break. The observed shear zone is continuous through the Garlock fault, which does not show any evidence of left-lateral slip during the same time period. A dislocation model of the observed shear indicates right-lateral slip at 7 ± 3 mm/yr on a vertical fault below ∼5 km depth, a rate that is two to three times greater than the geologic rates estimated on northwest-trending faults in the eastern Mojave area. This transient slip rate and the absence of resolvable slip on the Garlock fault may be the manifestation of an oscillatory strain pattern between interacting, conjugate fault systems.