Fault growth and rupture history based on displacement distribution along the Luoshan Fault, NW China

Abstract

The growth and development of faults are driven by repetitive earthquakes, which accumulate displacement and extend rupture lengths. This process changes fault morphology, resulting in surface ruptures that are preserved in the geomorphology as displaced landforms. High-resolution geomorphic data enable the precise acquisition of these displaced landforms, facilitating detailed analysis of slip distributions along faults and offering quantitative constraints on the growth and rupture history of faults. In this study, an airborne light detection and ranging (LiDAR) system was employed to obtain 0.5-m resolution geomorphic data >500 m long on both sides of the Luoshan Fault on the northeastern Tibetan Plateau. By interpreting and distinguishing different geomorphic markers, we identified and measured 436 right-lateral offsets along the Luoshan Fault. Based on statistical analysis methods, we determined that there were six strong earthquakes within 10 m of the cumulative displacement along the Luoshan Fault. Except for the latest event, the other five strong events showed regular displacement increments of approximately 1.9 m, revealing a strong earthquake pattern of approximate characteristic slip. The different cumulative displacement distributions correspond to various stages of fault growth. The growth pattern of the Luoshan Fault evolves from fault tip propagation and linkage (Events 1–5) to a mode of growth with a constant fault length but increased cumulative displacement (Event 6). Based on the displacement distribution along the Luoshan Fault, the northern segment is more likely to experience earthquake events, with magnitudes ranging from Mw 6.84 to 7.12.