4D imaging reveals tensile strain driven and chain-like collapse in hydrate-bearing sediments

Ultra-deepwater and shallow gas reservoirs, once regarded as hazards, are increasingly seen as valuable resources because of their vast reserves. Their stability depends critically on the integrity of the caprock, often a hydrate–sand composite that governs gas retention and prevents leakage, yet hydrate-bearing sediments (HBS) failure mechanisms remain poorly understood. Here we use a novel 4D in situ microstructural imaging method to provide the first direct visual evidence of a tensile strain-driven, chain-like hydrate damage process. This process follows a reproducible sequence of compressive stress concentration, crack propagation, free rotation, rotation limit, tensile stress redistribution, cementation network disintegration, and structural collapse. We show that tensile strain initiates this chain-like cementation failure, generating continuous weak layers that promote systematic sediment slippage and ultimately caprock failure. These insights establish a mechanistic basis for predicting caprock instability, guiding the design of sealing systems with improved damage tolerance, and enabling early warning frameworks in challenging subsea environments. Beyond gas hydrate systems, the findings have broader relevance for subsea infrastructure protection, continental slope stability, and the secure exploitation of unconventional offshore energy resources.