Decorrelation and Deformation: Sentinel-1 InSAR Analysis of the March 2025 Earthquake in Central Myanmar and along the Sagaing Fault

Abstract

A moment magnitude (Mw) 7.7 earthquake, as reported by the U.S. Geological Survey (USGS), struck central Myanmar on 28 March 2025. Its epicenter was situated near the Sagaing Fault, a major right-lateral strike-slip fault system that accommodates the relative motion between the Indian and Sunda plates. As one of Southeast Asia’s most active tectonic structures, the Sagaing Fault has a history of producing destructive earthquakes, and this event caused significant ground displacement and surface rupture particularly across the Mandalay and Sagaing regions, which lie directly along its central segment. Using Sentinel-1 satellite imagery and advanced Interferometric Synthetic Aperture Radar (InSAR) techniques, the co-seismic deformation was mapped and quantified with high precision, revealing clear patterns of displacement. Interferometric phase analysis indicated a reported maximum line-of-sight (LOS) pixel displacement of 52.0 cm, which requires coherence and phase-unwrapping validation before it can be interpreted as ground displacement concentrated near the fault trace while coherence analysis showed localized areas of signal decorrelation corresponding to intense ground disturbance. To refine rupture mapping, the Normalized Coherence Change Index (NCCI) was applied for the identification of severely damaged zones. Spatial analysis further indicates that as the distance from the epicenter increases, the deformation amplitude gradually decreases, which is consistent with the typical elastic strain release of strike-slip faults. Quantitative assessments were conducted by dividing the affected area into multiple zones for the evaluation of displacement gradients and rupture extent. The results provide new insights into the mechanics of active fault systems in central Myanmar and reveal the spatial patterns of ground movement associated with large-magnitude seismic events. These findings identify regions of high seismic vulnerability and highlight the importance of remote sensing combined with ground-based observations for hazard assessment, infrastructure resilience planning and earthquake preparedness.