Development characteristics and mechanism of geological hazards in natural gas hydrate development area of Qiongdongnan basin

The Qiongdongnan basin (QDNB) in the northern South China Sea (SCS) has been confirmed to host significant natural gas hydrate deposits through extensive geological surveys and drilling results. However, gas hydrate occurrences are typically associated with a series of potential geological hazards that can significantly impact offshore engineering, environmental climate, and other aspects. Based on published literature and high-resolution 2D and 3D seismic data of the QDNB, areal geohazards related to gas hydrates are investigated. We identify and characterize different types of geological hazards, outlining their development characteristics and models. Combined with the regional tectonic and sedimentary background, the genetic mechanisms underlying each hazard type are analyzed comprehensively. Our findings demonstrate that abundant provenance, high-temperature overpressure, a complex tectonicsedimentary background, and abundant organic matter are the main causes of gas hydrate accumulation and associated seabed geological hazards in the QDNB. The region exhibits a diverse range of geological hazards, with interacting factors often influencing each other in complex ways. Among these, submarine landslides are most closely linked to gas hydrate occurrences, with hydrate formation and decomposition dynamically intertwined with landslide processes. Considering the current state of domestic seabed geohazard research, monitoring, and early warning systems, this study highlights key areas for future research. Furthermore, it and provides a valuable reference for the safe and sustainable commercial exploitation of gas hydrates in the QDNB, emphasizing the need for comprehensive risk assessments and mitigation strategies to address the potential hazards associated with these valuable energy resources. © 2024 Geological Society of China. All rights reserved.