Near-Surface Hydrologic Influences on Sagaing Fault Surface Rupture During the 2025 Mw 7.7 Mandalay, Burma (Myanmar) Earthquake

Abstract

On 28 March 2025, the Mw 7.7 Mandalay earthquake ruptured ∼475 km of the Sagaing fault. The surface rupture was mapped using high-resolution satellite optical images guided by displacements from subpixel optical image correlation. The surface rupture was generally continuous where remotely observable (i.e., not tree-covered) and very simple without large steps or bends along strike. We analyze remote surface rupture mapping from pixel tracking and optical images and determine that ∼10% of the surface rupture passed through potentially saturated ground. The ground saturation observed on high-resolution satellite images was compared with Sentinel-2 normalized differential water index and generally agrees spatially. We test for correlations between ground saturation observations and the presence or absence of surface rupture and of strike-slip geomorphology. We infer that transient near-surface conditions, such as ground saturation, may influence the geomorphic and paleoseismic preservation of surface rupture, as well as infrastructure (dam) performance, both in this earthquake and globally.