Numerical modeling of the subaerial landslide source of the 22 December 2018 Anak Krakatoa volcanic tsunami, Indonesia. (1st January 2020)

• Record Type: Journal Article
• Authors: Heidarzadeh, Mohammad; Ishibe, Takeo; Sandanbata, Osamu; Muhari, Abdul; Wijanarto, Antonius B.
• Is Part Of: Ocean engineering. Volume 195(2020)
• Publication Date: 2020-01-01
• Subjects: Volcanic tsunami -- Anak Krakatoa -- Sunda Strait -- Numerical simulations -- Indonesia -- Wavelet; Ocean engineering -- Periodicals; Ocean engineering; Periodicals; 620.4162
• DOI: 10.1016/j.oceaneng.2019.106733
• Languages: English
• ISSNs: 0029-8018

Abstract

Abstract: The eruption of the Anak Krakatoa volcano (Indonesia) in December 2018 produced a destructive tsunami with maximum runup of 13 m killing 437 people. Since the occurrence of this rare tsunami, it has been a challenge as how to model this tsunami and to reconstruct the network of coastal observations. Here, we apply a combination of qualitative physical modeling and wavelet analyses of the tsunami as well as numerical modeling to propose a source model. Physical modeling of a volcano flank collapse showed that the initial tsunami wave mostly involves a pure-elevation wave. We identified initial tsunami period of 6.3–8.9 min through Wavelet analysis, leading to an initial tsunami dimension of 1.8–7.4 km. Twelve source models were numerically modelled with source dimensions of 1.5–4 km and initial tsunami amplitudes of 10–200 m. Based on the qualities of spectral and amplitude fits between observations and simulations, we constrained the tsunami source dimension and initial amplitude in the ranges of 1.5–2.5 km and 100–150 m, respectively. Our best source model involves potential energy of 7.14 × 10 13 –1.05 × 10 14 J equivalent to an earthquake of magnitude 6.0–6.1. The amplitude of the final source model is consistent with the predictions obtained from published empirical equations. Highlights: Initial tsunami wave is a pure-elevation wave based on our physical modeling. The dominant tsunami period is 6.3–8.9 min giving tsunami length of 1.8–7.4 km. Final tsunami source has a length of 1.5–2.5 km and amplitude of 100–150 m. Our model has energy of 7.14 × 10 13 –1.05 × 10 14 J equivalent to M 6.0 earthquake.