Proceedings of the 12th International INQUA meeting on paleoseismology, active tectonic and archaeoseismology

G E O L O G I C A L S E T T I N G We propose The Selayar-Alor Ridge name for the underwater ridge running east-west from Selayar Island to Alor Island (red dashed lines inFig. 1). The Selayar-AlorRidge is a tectonically active zone in the Banda-arc system is characterized by the interaction between the subduction of the oceanic crust and the collision of continental crust (Purwandono et al., 2019). The Banda-arc system is home to various microcontinents, including Sumba, west Sulawesi, Banggai, Tukang Besi, and Buton (Koesoemadinata, 2020). The Selayar-Alor Ridge borders the Flores Basin, the western Banda Basin, and the lesser Sunda islands, with the Flores Sea dominated by an accretionary wedge, inactive volcanism, and active faults (Rahardiawan & Purwanto, 2014). The region's seismic activity has resulted significant earthquakes, such as the 7.2 Mw earthquake north of Maumere in 1992, which was followed by a 26.2 m tsunami (Imamura et al., 1995), and the 7.8 Mw earthquake in the Flores Sea in 1996, one of the deepest in world history (Wiens, 1998). The area also experienced the 2021 7.4 Mw Kalaotoa fault earthquake, unique for its lack of a strike- slip fault (PUSGEN 2017). Fig. 1 : Location of 14 December 2021 M7.4 mainshock. The focal mechanism from BMKG (Meteorological, Climatological, and Geophysical Agency of Indonesia) shows a strike-slip mechanism north of the Florest Thrust. The reds clusternext to mainshock represent aftershock data from Supendi et al. (2022). Red lines depict the main tectonic features of Eastern Indonesia. East-West fault with the dashed lines are from this study.