Displacement-Length Scaling for Thrust Faults

This study used high-resolution, two- and three-dimensional, seismic-reflection data from the Niger Delta, Sichuan Basin, and Magdalena Basin to analyze displacement profile patterns and scaling relationships between the maximum displacement and length (Dmax v. L) of thrust faults, referred to as displacement-length scaling relationships. The thrust faults mapped in this study exhibited highly variable displacement profiles, both in terms of shape and overall magnitude of displacement. A robust power-law displacement-length scaling relationship was obtained for all three data sets combined, yielding a scaling relationship (n = 0.87) close to the linear fit most often observed for normal faults and thrust faults. At the regional scale, however, a robust fit was obtained only for the Sichuan Basin, and with a nonlinear displacement-length scaling relationship (n = 0.58) suggesting scale dependence in this region. Many displacement profiles exhibited steep displacement gradients at the fault tips and shallow gradients in between, often with multiple maxima. These features are interpreted with conceptual growth models for thrust faults: hard linkage and soft linkage fault interaction models, a detachment linkage fault interaction model, and an overburden-limited, fault-growth model.

Displacement-Length Profiles

Selected displacement profiles for individual faults in the Niger Delta (NDN), Sichuan Basin (SBS and SBN), and the Magdalena Basin (MBS and MBN). All plots are five times vertically exaggerated. Gray boxes at the tips represent uncertainties in the exact positions of lateral fault terminations. The shapes of displacement profiles are extrapolated into these regions.