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

106 PATA Days 2024 Fig. 1: Main stratigraphic profile made at Campiche lowland. Yellow layer shows the sandy unit interpreted as the deposit of the 1730 central Chile tsunami. Here, we report the first robust geologic evidence for the 1730 tsunami inundation and inconclusive evidence for associated coastal subsidence. We complement it with local inundation chronicles and numerical experiments to test the hypothesis of large slip offshore metropolitan Chile in 1730. Evidence comes from Campiche lowland, a former coastal lagoon fringing the northern shore of Quintero Bay, 5 km northwest from where the mid-Holocene tsunami sequence was reported (Dura et al., 2015). At Campiche we found a widespread, tabular, clean sand sheet, interbedded in the mud that filled in the lagoon (Fig. 1). The ~10 cm thick sand sheet sharply punctuates the mud and extends and pinches out 2 km inland from the coast. Locally, it overlies a strongly eroded mud horizon and contains abundant mud rip- up