Formation of Double Bottom Simulating Reflectors Induced by Submarine Landslides: A Case Study from the Shenhu Area, Northern South China Sea

The destabilization of gas hydrate systems can trigger both gas release and submarine landslides. While such landslides frequently generate slump masses that exhibit bottom-simulating reflectors (BSRs) or double BSRs (DBSRs)， the mechanisms governing the formation of these features remain poorly constrained. In the Shenhu area of the northern South China Sea， we identify several seismically imaged DBSRs linked to landslide. By integrating high-resolution seismic and ocean bottom seismometer (OBS) data with drilling records， we modeled the gas hydrate stability zone (GHSZ) and investigated the origin of these seismic features. OBS derived velocity analysis and equilibrium simulations suggest that the upper BSR1 corresponds to the present-day base of the GHSZ， whereas the lower BSR0 is interpreted as a relict paleo-base resulted from the landslide event. This correlation establishes a genetic connection between slope instability and the dynamic evolution of the gas hydrate system. We conclude that landslide structures serve as key geomorphic indicators of past shifts in the GHSZ， while associated BSRs/DBSRs provide direct geophysical evidence for the accumulation of gas hydrates and free gas. Consequently， these features form a robust set of criteria for prospecting gas hydrate resources， offering a practical framework for predictive exploration models in analogous offshore basins.