A Tsunami Generated by a Strike‐Slip Event: Constraints From GPS and SAR Data on the 2018 Palu Earthquake

A devastating tsunami struck Palu Bay in the wake of 28 September 2018 Mw = 7.5 earthquake (Sulawesi, Indonesia). With a predominantly strike-slip mechanism, question remains whether this unexpected was generated by itself, or rather earthquake-induced landslides. In study we examine potential co-seismic deformation. To end, present novel geodetic dataset GPS and multiple SAR-derived displacement fields to estimate 3D surface deformation field. The data reveal number fault bends, conforming our interpretation tectonic setting as transtensional basin. Using Bayesian framework, provide robust finite solutions slip distribution, incorporating several scenarios tectonically feasible orientations below bay. These involve large uplift ( > 2 m) bay due thrusting on restraining bend that connects offshore continuation two parallel onshore segments. estimates input simulate cases. For most locations for which video-derived waveforms are available models qualitative fit leading wave arrival times polarity. modeled tsunamis explain observed runup. We conclude main driver behind followed earthquake. Our unique constrains vertical motions sea floor, sheds new light tsunamigenesis faults basins.