Insights into potential submarine landslide tsunamis in the South China Sea: A comparative study of the Baiyun Slide and the Brunei Slide

We investigate the sliding dynamics of two giant submarine landslides and their tsunamigenic capacity in the South China Sea (SCS) region: the Baiyun slide in the Pearl River Mouth Basin and the Brunei Slide in Northwest offshore Brunei. The two slides have comparable sizes with the estimated volumes of 1035 km³ for Baiyun Slide versus 1200 km³ for Brunei Slide and areas of 5500 km² versus 5300 km². Based on the available geophysical observations, we construct hypothetical scenarios for both slides. By treating the slides as translational mudflow, we are able to reproduce the observed run-out distribution of the Baiyun Slide. The sliding speeds of the failed material could reach 25~35 m/s in both slide events. Both slides could generate devastating tsunamis in the SCS although the tsunamigenic capacity of the Brunei Slide is significantly larger than the Baiyun Slide. Through a series of numerical experiments, we demonstrate that the steepness of the slope and initial water depth of the slides play the key role of determining their tsunamigenic capacity. The tsunami generated by the Baiyun Slide mainly affects the northern part of the SCS. Coastlines including the southern China, central Vietnam, western Philippines suffer the highest tsunami waves.  The tsunami waves generated by the Brunei Slide causes significant impact in northern coasts of Borneo Island, coasts of central and southern Vietnam and Palawan.