Impact of earthquakes on tropospheric delays—case studies of the 2025 Tibet Mw6.8 and Myanmar Mw7.9 earthquakes

Earthquakes release energy that triggers crustal deformation and atmospheric disturbances via surface waves, affecting the GNSS tropospheric delay. This study focuses on the 2025 Tibet MW6.8 and Myanmar MW7.9 earthquakes. Using ECMWF's numerical weather model (NWM) and ray-tracing, it inverts the tropospheric delay (0.25° grid, epicentre-centred) and analyzes its spatiotemporal characteristics and earthquake-induced non-isotropy changes. Results show earthquakes alter tropospheric delay's temporal evolution: dry delay shifted from a pre-seismic decrease to a post-seismic increase in both quakes, while wet delay reversed or adjusted. Spatially, high-altitude Tibet had more obvious dry delay anomalies (post-seismic decrease, largest in east), low-altitude Myanmar had larger wet delay changes (post-seismic increase, significant in north)—differences linked to topography, focal mechanisms, and co-seismic deformation. Fault types dominated spatial responses: Tibet's normal fault enhanced NE correlation; Myanmar's strike-slip weakened SW–NE symmetry. Earthquakes also modified non-isotropy: Tibet's post-seismic non-isotropy mean dropped 18% (10° clockwise rotation, synced with tensile stress); Myanmar's rose by 24% (negative zones shifted NW–SW and positive zones rotated SE–NE). This study informs high-precision tropospheric delay correction models and improves GNSS positioning in quake-affected areas.