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

176 1 2 T H I N T E R N AT I O N A L I N Q U A M E E T I N G O N PA L E O S E I S M O L O G Y , A C T I V E T E C T O N I C S A N D A R C H A E O S E I S M O L O G Y ( PATA ) , O C T O B E R 6 T H - 1 1 T H , 2 0 2 4 , L O S A N D E S , C H I L E PATA Days 2024 (1) Departamento de Geología. Universidad de Chile. Plaza Ercilla 803, Santiago, Chile. (2) Universidad Rey Juan Carlos, Móstoles, Madrid, España. *Email: mforch@gmail.com / geaston@uchile.cl Maximiliano Forch (1) Gabriel Easton (1) Manuel Abad (2) GEOLOGICAL RECORD OF HOLOCENE TSUNAMIS IN THE CARRIZAL BAJO WETLAND (~28°S) , ATACAMA DESERT, CHILE A B S T R A C T The coastline of the Atacama region has been subjected to significant marine flooding events since prehistoric times, driven by catastrophic tsunami waves generated by local and regional earthquakes, as well as by some events originated in distant regions of the Pacific Ocean. Consequently, the study of sedimentary records of past tsunamis can improves tsunami hazard assessment in coastal regiones where historical record is scarce, such as the Atacama region in northern Chile. From a geomorphological analysis coupled with the study of pits in the Carrizal Bajo wetland, we determined 13 distinctive sandy layers interpreted as paleotsunami deposits, generated in the last 2500 years, which include the last 1922 event. This significantly increases our knowledge on the impact of past tsunamis in the region and point to reassess the impact of historical and prehistoric tsunamis on the northern coasts of Chile. I N T R O D U C T I O N In northern Chile the coastline of the Atacama Desert is exposed to significant earthquakes and large tsunamis associated with the subduction of the Nazca Plate beneath the South American Plate (Figure 1). However, historical and geological records of tsunamis and paleotsunamis in this region are scarce (León et al., 2019; Abad et al., 2020; Easton et al., 2022; Salazar et al., 2022). In addition to the recorded historical tsunamis in Chile, there is also evidence of ancient events along the northern coasts of the country for which no historical records or written observations exist (paleotsunamis; León et al., 2019; Abad et al., 2020; Easton