Studying the impact of strong near-field and far-field earthquakes on earthfill reservoir dams: an integrated satellite and instrumental monitoring approach

Abstract

Ensuring the seismic safety of ageing earthfill reservoir dams in tectonically active regions requires methods that link field monitoring directly to quantitative structural assessment. Existing studies, however, typically treat satellite deformation monitoring and dynamic structural modeling as separate activities. This study addresses that gap by developing an integrated framework that combines a national electronic seismic-monitoring platform, real-time instrumental accelerograms, and multi-year Sentinel-1 satellite radar interferometry (InSAR) within a single, traceable chain of analytical and finite-element models. The framework is applicable to both near-field and far-field earthquakes; here it is applied to the earthfill Surkhan reservoir dam (Uzbekistan) following the strong far-field earthquake that occurred in Afghanistan on 3 November 2025 ( M = 6.8, h = 30 km). Seven years of InSAR data (2017-2023) show that the dam deformation is predominantly seasonal, governed by the reservoir loading cycle, with point-wise cumulative trends that require continued monitoring, while the instrumental records show that the earthquake added only a sub-millimeter transient response well within the elastic range. The macroseismic intensity prediction agrees closely with the instrumental observation, whereas the free-field ground-motion model under-predicts the recorded acceleration by more than an order of magnitude, possible explanations include local site and crest amplification, sensor position and processing, and event-specific source effects, and these remain to be examined against the raw records; the observed site intensity (5 MSK-64) was two intensity degrees below the design-basis intensity of the dam (7 MSK-64). The novelty of the work lies in the joint interpretation of long-term satellite and short-term seismic datasets through one traceable model chain, partially checked against the monitored intensity and displacement quantities, yielding a low-cost, replicable methodology for the rapid post-earthquake safety assessment of reservoir dams in seismically active regions.