Complex tsunami hazards in eastern Indonesia from seismic and non-seismic sources: Deterministic modelling based on historical and modern data

Abstract

Eastern Indonesia is one of the world’s most complex regions in terms of tsunami hazards, as it accommodates numerous seismic and non-seismic tsunami sources with a history of deadly tsunamis. This study is an effort to enhance tsunami hazard knowledge in eastern Indonesia where limited data and analyses exist. We provide a brief understanding of eastern Indonesia’s tsunami hazards by modelling selected deterministic tsunami scenarios from tectonic, submarine mass failure (SMF), and volcanic sources. To our knowledge, this is the first time that tsunami hazards modelling from such diverse sources in Indonesia has been performed. Our methodology is a deterministic tsunami hazard analysis considering credible tsunami sources from historical and contemporary data, modelling them using state-of-the-art simulation tools. We modelled two Mw7.8 tsunamigenic earthquake scenarios on the Flores back-arc thrust, one rupturing the basal fault (FBT-BF) and the other rupturing the splay fault (FBT-SF), showing that the two scenarios produce maximum tsunami amplitudes of $$\sim$$ ∼ 5.3 m and $$\sim$$ ∼ 4.2 m, respectively, which are comparable to the deadly 1992 Flores tsunami. We modelled potential SMF-generated tsunamis in the Makassar Strait with SMF volumes of 5 $$\hbox {km}^3$$ km 3 and 225 $$\hbox {km}^3$$ km 3 which yielded maximum tsunami heights of $$\sim$$ ∼ 1.1 m and $$\sim$$ ∼ 4.3 m along the eastern coast of Kalimantan Island and $$\sim$$ ∼ 2.9 m and $$\sim$$ ∼ 11.1 m along the west shore of Sulawesi Island, respectively. The 1871 Ruang volcanic tsunami is studied through existing historical documents and a source model is proposed comprising a flank collapse with volume of $$0.10\ \mathrm{km}^3$$ 0.10 km 3 . Such a source model successfully reproduced the 25 m runup reported in a historical account.

Tsunami hazard in Lombok and Bali, Indonesia, due to the Flores back-arc thrust

“…The best-documented tsunamigenic earthquake on the Flores Thrust occurred in its far eastern part (Yeh et al, 1993;Imamura and Kikuchi, 1994;Tsuji et al, 1995;Pranantyo et al, 2021). The 1992 M w 7.9 Flores Island earthquake injured 2144 people and killed 2080 (Yeh et al, 1993;Tsuji et al, 1995;Fig.…”

Landslide Induced Tsunami Hazard at Volcanoes: the Case of Santorini

“…Several authors have applied this method for modeling landslide tsunamis in the past (Heidarzadeh & Satake, 2017; Okal & Synolakis, 2004;Synolakis et al, 2002;Tappin et al, 2008). A major challenge in modeling subaerial landslide tsunamis is estimating the dimension and amplitude of the initial waves generated by landslides (Fritz et al, 2004;Heidarzadeh et al, 2020aHeidarzadeh et al, , 2020bMcFall & Fritz, 2016;Pranantyo et al, 2021). Here, we assume that the initial wave generated by the subaerial landslides due to volcanoes has a Gaussian shape and thus we consider two parameters for the initial waves comprising maximum initial wave amplitude (A i ) and the initial length of the sea-surface displacement (L i ); subscript ''i'' is used to mark the initial waves (Fig.…”

Identification and ranking of subaerial volcanic tsunami hazard sources in Southeast Asia

“…Other volcanoes in Southeast Asia are not as commonly considered. Pranantyo et al (2021) test the tsunami propagation from Ruang volcano, Indonesia, using and comparing both historical observations and data from the 2018 Anak Krakatau event and reproducing a 25 m runup in the near field. In Papua New Guinea numerical tsunami models have almost exclusively been considered for the Ritter Island tsunami in 1888 and the reconstruction of its generation (Karstens et al, 2020;Ward and Day, 2003).…”