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Copyright © The Author(s) 2022. Eastern Mediterranean Sea has experienced four tsunamigenic earthquakes since 2017, which delivered moderate damage to coastal communities in Turkey and Greece. The most recent of these tsunamis occurred on 30 October 2020 in the Aegean Sea, which was generated by an Mw 7.0 normal-faulting earthquake, offshore Izmir province (Turkey) and Samos Island (Greece). The earthquake was destructive and caused death tolls of 117 and 2 in Turkey and Greece, respectively. The tsunami produced moderate damage and killed one person in Turkey. Due to the semi-enclosed nature of the Aegean Sea basin, any tsunami perturbation in this sea is expected to trigger several basin oscillations. Here, we study the 2020 tsunami through sea level data analysis and numerical simulations with the aim of further understanding tsunami behavior in the Aegean Sea. Analysis of data from available tide gauges showed that the maximum zero-to-crest tsunami amplitude was 5.1–11.9 cm. The arrival times of the maximum tsunami wave were up to 14.9 h after the first tsunami arrivals at each station. The duration of tsunami oscillation was from 19.6 h to > 90 h at various tide gauges. Spectral analysis revealed several peak periods for the tsunami; we identified the tsunami source periods as 14.2–23.3 min. We attributed other peak periods (4.5 min, 5.7 min, 6.9 min, 7.8 min, 9.9 min, 10.2 min and 32.0 min) to non-source phenomena such as basin and sub-basin oscillations. By comparing surveyed run-up and coastal heights with simulated ones, we noticed the north-dipping fault model better reproduces the tsunami observations as compared to the south-dipping fault model. However, we are unable to choose a fault model because the surveyed run-up data are very limited and are sparsely distributed. Additional researches on this event using other types of geophysical data are required to determine the actual fault plane of the earthquake. National Science Foundation under Cooperative Support Agreement; Royal Society

Tsunami potential from high dip-angle splay faults is an understudied topic, although such splay faults can significantly amplify coastal tsunami heights as compared with ordinary thrust faults. Here, we identify a hotspot for tsunamis from splay faulting in the Molucca Sea arc–arc collision zone in eastern Indonesia, which accommodates one of the world’s most complicated tectonic settings. The November 2019 Mw 7.2 earthquake and tsunami are studied through teleseismic inversions assuming rupture velocities in the range 1.5–4.0 km/s followed by tsunami simulations. The normalized root mean square error index was applied and revealed that the best model has a rupture velocity of 2.0 km/s from the steeply dipping plane. The recent high dip-angle reverse 2019 Mw 7.2 and 2014 Mw 7.1 earthquakes combined with numerous similar seismic events may indicate that this region is prone to splay faulting. This study highlights the need for understanding tsunamis from splay faulting in other subduction zones.

© Copyright 2021 The Author(s). We studied the February 23rd, 1969 M7.0 Majene, Sulawesi earthquake and tsunami. It was followed by tsunami reported at five locations. At least 64 people were killed and severe damage on infrastructures were reported in Majene region. Based on damage data, we estimated that the maximum intensity of the earthquake was MMI VIII. Focal mechanisms, derived using first motion polarity analysis, indicated that the earthquake had a thrust mechanism. Furthermore, we built hypothetical earthquake scenarios based on a rectangular fault plane of 40 km × 20 km with a homogeneous slip model of 1.5 m. We run the Open Quake and the JAGURS code to validate the macroseismic and tsunami observation data, respectively. Our best-fitted earthquake model generates maximum intensity of 8+ which is in line with the reported macroseismic data. However, the maximum simulated tsunami height from all scenario earthquakes is 2.25 m which is smaller than the 4 m tsunami height observed at Pelattoang. The possibility of contribution of another mechanism to tsunami generation requires further investigation. Royal Society, UK (grant number CHL\R1\180173).

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$$\hbox {km}^3$$km3and 225$$\hbox {km}^3$$km3which 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$$0.10\ \mathrm{km}^3$$0.10km3. Such a source model successfully reproduced the 25 m runup reported in a historical account.