Buckling contributes to both coseismic uplift and long-term fold growth in active fold-thrust belts

Abstract Understanding the interplay among fault slip, fold growth, and earthquakes is crucial for assessing earthquake risk and deciphering the relationship between long-term and short-term deformation in fold-thrust belts. While fault-related folding theories have dominated previous studies, the role of the buckling process—characterized by bed-parallel contraction—in seismicity and fold development has been underreported. Herein, we attempt to address this issue through an examination of the 28 March 2019 M5.0 Mangya earthquake in the Shizigou anticline, western Qaidam Basin (northern Tibetan Plateau), based on 3-D seismic imaging data, interferometric synthetic aperture radar (InSAR) analysis, and borehole loggings. We show that this earthquake was not caused by slip along known faults, but by interbed slip due to buckling in the limb of the anticline, demonstrating for the first time that buckling could result in moderate earthquakes. The buckling process not only leads to coseismic uplift deviating from the folding crest induced by slip on the underlying fault, but also modulates the long-term geometric growth of the Shizigou anticline. Our findings underscore the significance of the buckling process in contributing to short-term coseismic slip and long-term fold growth in active fold-thrust belts.