Source mechanism and rupture directivity of small earthquakes in the Changning region, China, using a dense array data
Integrating focal mechanism solutions with rupture directivity analysis enables high-resolution characterization of subsurface fault geometry and earthquake rupture processes. However, resolving these parameters for small-magnitude earthquakes remains challenging due to small rupture sizes, short durations, and low signal-to-noise ratio (SNR). Here, we utilized a dense array of nodal seismometers in the Changning region, Sichuan Basin, China, to study the focal mechanism and rupture directivity of aftershocks following the 2019 Ms 6.0 induced earthquake. Using PhaseNet+ and SKHASH, we first enhance the focal mechanism catalog (1 1), and their spatial variability reflects a long-term interplay between fluid injection and faults in the salt-mining area. These findings illuminate a complex fault system beneath the Changning anticline and highlight the importance of high-resolution seismic arrays in resolving rupture processes of small-magnitude events.