Aftershock characteristics of the M_W7.7 Myanmar earthquake, March 2025

On March 28, 2025, a M_W7.7 earthquake struck central Myanmar. In this study, an aftershock catalog recorded by the Seismic Monitoring Center of the Thailand Meteorological Department (TMD) was used to analyze the characteristics of the aftershock sequence. The TMD network detected events to M_L3.0 for the Sagaing Fault and Myanmar M_W7.7 earthquake, with an additional 0.2 applied as a conservative lower bound. The majority (89%) of M_L≥5.5 aftershocks occurred within 16 days of the mainshock. Epidemic-Type Aftershock Sequence modeling revealed that α=2.023, indicating a reduced capacity to trigger secondary aftershocks, while p=1.17, reflecting rapid decay. These slightly high α- and p-values may be due to supershear rupturing, the high slip rate of the Sagaing Fault, and warm crustal conditions. The difference in magnitude between the largest aftershock and mainshock was 1.0, which is consistent with regional historical sequences. The spatial distribution of aftershocks was controlled by the N–S-trending Sagaing Fault, and was closely related to the mainshock slip, fault geometry, and historical rupture zones. The spatial fractal dimension (D_C=1.60) indicated a fractal structure, reflecting the complexity of the regional fault structure and the spatial distribution of small earthquakes. After the M_W7.7 event, the south-central Sagaing Fault ruptured, except for the Bago segment. However, the northern end of the Bago segment has the potential to produce up to a M_W7.0 earthquake.