Numerical study of the triggering mechanism of the 2018 Anak Krakatau tsunami: eruption or collapsed landslide?

The eruption and collapse of the Anak Krakatau volcano generated tsunamis in the Sunda Strait on December 22, 2018, leading to damage and casualties. In this paper, we use the two-layer model and nonlinear shallow equation model to study the triggering mechanism of the tsunami event. We first simulate the tsunami generated by volcano eruption and landslide, respectively. The tsunami source is analyzed by comparing with gauge measurements. It indicates that the volume of partial collapse for the landslide is 0.2–0.3 km3. The comparison between the numerical results of landslide and tide gauge measurements presents well-fitted results, especially for the leading tsunami waves and arrival time. Computed maximum tsunami amplitude distribution points out that the most hazardous area is located at the south of the Sunda Strait (Pandeglang), which suffered the most casualties.