Submarine geohazards on the northwestern continental margin of the South China Sea and their mechanism

Abstract

Submarine geohazards significantly threaten human economic activities and essential infrastructure. Based on multi-beam data and high-resolution 2D seismic data, two types of submarine geohazards are identified: direct and indirect geohazards on the northwestern continental slope and the Xisha Uplift of the South China Sea (SCS). Direct geohazards include submarine landslides and active faults, while indirect geohazards include buried channels, submarine canyons, pockmarks, volcanoes and magma diapirs. This study comprehensively analyzes geomorphological features, including their characteristics, genesis and distribution. Statistical analysis reveals that the gradient of the Xisha Uplift slope is steeper than the shelf break, making it a more unstable region. However, assessing disaster potential indicates that submarine geohazards at the shelf break pose a greater threat than those at the Xisha Uplift. Many factors, including tectonic activity, sediment supply and relative sea-level changes, influence submarine geohazards' formation. These hazards do not occur in isolation but often interact with one another. The research results provide a scientific basis for predicting deep-sea geohazards near the northern continental margin and Xisha Island in the SCS.