Intermittent supershear rupture punctuated by barrier-induced stopping phase during the 2025 Mw 7.8 Myanmar Earthquake: Evidence from near-fault strong motion observation

Xiaotian Ding, Shiqing Xu , Lingling Ye

Supershear rupture has been investigated by many studies, yet its exact characteristics during natural earthquakes are not fully clear, due to the paucity of near-field constraints. Here we analyze the strong motion data recorded at a near-fault station during the 2025 Mw 7.8 Myanmar earthquake to estimate the detailed source process around that station. By comparing simulated velocity waveforms under various conditions with the observed one, we find that a supershear rupture with speed surpassing √2 times S wave speed is required to fit the first-order features of the observation. Moreover, a fault barrier at ~6 km south of the station is inferred by the reversed-polarity fault-parallel secondary pulse following the main pulse, interpreted as a stopping phase. Together with other information, the results suggest an overall fast yet intermittent rupture process during the 2025 Myanmar earthquake, with the inferred barrier likely representing a segmentation boundary for the Sagaing fault.