Characteristic Displacement and Paleoearthquake Activity of the Xiaojiang Fault Mapped from Historical Image Data and Tectonic Implications

Abstract Understanding the displacement characteristics of active faults is essential for reconstructing the recurrence behavior of large earthquakes and evaluating seismic hazards. Quantifying surface offsets provides key evidence for identifying individual and cumulative rupture events and for testing whether a fault exhibits characteristic slip behavior. In this study, we investigated the northern segment of the Xiaojiang fault, one of the most seismically active strike-slip faults in the southeastern Tibetan Plateau. To evaluate the single- and multievent cumulative offsets of streams along the fault, we analyzed historical aerial photographs from the 1950s and Keyhole satellite images from 1968. Despite extensive recent anthropogenic modification of the landscape, these historical datasets preserve original geomorphic markers that record surface displacements from multiple earthquakes. A cumulative-offset probability density analysis reveals characteristic slip increments of approximately 7 m, corresponding to at least five surface-rupturing events since the Holocene. The results indicate that the northern Xiaojiang fault follows a characteristic slip model with an average recurrence interval of ∼1000 yr and a left-lateral slip rate of ∼7 mm/yr. These findings enhance our understanding of the fault’s long-term behavior and its role in accommodating regional crustal deformation along the southeastern margin of the Tibetan Plateau.