Landslide triggered tsunami modelling: A study in Anak Krakatoa collapse

Abstract

The Anak Krakatoa volcano in Sunda Strait is a tsunami threat to the southern part of Sumatra Island and the west part of Java Island as the eruptions and landslides it generates may trigger a tsunami. As the coasts of West Java are densely populated areas, if a tsunami occurs, then the loss and casualties would be massive. Therefore, a hazard assessment in the area is necessary which includes a simulation of possible tsunami occurring in the region. We simulated the 2018 tsunami in Sunda Strait triggered by the collapse of the Anak Krakatoa flank using the landslide parameters inferred from previous studies simulating that the 2018 tsunami event. The water wave propagation in this simulation demonstrates a tsunami that travels rather fast, where the tsunami reaches the Panaitan Island in 20 minutes and has reached the mainland around 30 minutes. The simulated landslide created a water wave amplitude as high as 60 m in the nearby islands of Krakatoa Archipelago, down to less than 10 m in the mainland of Java Island. This result relatively correlates with the run-up height data measured in the field by previous studies in 2019 and 2020. The shape of the coastline also determines how the water waves affect the area, which should be an essential factor in the hazard assessment.