Runup of landslide-generated tsunamis controlled by paleogeography and sea-level change

Reconstruction of the paleo-shoreline of South China Sea 0.54 million years ago suggests the Baiyun landslide generated waves of around 18 meters in height and highlights the importance of shoreline reconstructions for paleo-tsunami modelling Pre-Holocene landslides and tsunami deposits are commonly observed on continental margins and oceanic islands. However, scarce evidence has thus far linked pre-historic submarine landslides to particular tsunami events. This work focuses on an 839 km(3) submarine landslide that occurred in the South China Sea at 0.54 Ma. Bathymetric restorations show that the paleoshoreline at 0.54 Ma was 180-580 km to the south of its present-day location. In such a setting, the tsunami triggered by the landslide at 0.54 Ma was able to generate larger waves with shorter arrive times when compared to an equivalent landslide-generated tsunami under present-day conditions. This observation proves that tsunamis generated by submarine landslides during sea-level lowstands caused catastrophic damage to the South China Sea coast in the past, and so will do in future sea-level lowstands. This study stresses the importance of restoring paleoshorelines for detailed analysis of historic landslide-generated tsunamis.

Automated summary

Reconstruction of the paleo-shoreline of the South China Sea 0.54 million years ago reveals that the Baiyun landslide generated waves of around 18 meters in height, emphasizing the significance of shoreline reconstructions in studying prehistoric tsunamis.