Complex strike-slip faulting during the 2021 Mw7.4 Maduo earthquake

Abstract

Fault geometry is an essential component for understanding earthquake genesis and dynamic rupture propagation. Here we employed space-based geodetic observations and geological survey, adopting a fully Bayesian approach, to probabilistically estimate the fault geometry of the 2021 Mw7.4 Maduo earthquake. The fault is predominantly characterized by strike-slip motions with three main geometry irregularities, reflecting the segmented pattern of the earthquake rupture. On the west side of the epicenter, the fault exhibits north-dipping angles (75–81°), whereas on the east side, it shows sub-vertical angles (82–87°). For the southeast branch, geodetic inversion reveals an overall shallow-dipping (44 ± 5°) faulting, yet further segmentation of the branch in the model and analysis of aftershock mechnism indicate that the dip of the branch faults may vary between vertical and shallow angles. This finding warrants confirmation through future underground observation data.These results suggest that strike-slip faulting could occur on unsuitably orientated planes during any seismic event.