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

104 PATA Days 2024 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 K E Y W O R D S Tsunami geology, 1730 Chile tsunami, Metropolitan Chile coast (1) Instituto de Geografía, Pontificia Universidad Católica de Valparaíso. *Email: marco.cisternas@pucv.cl, matias.carvajal@pucv.cl, bsv004@alumnos.ucn.cl, mario.guerra@pucv.cl Marco Cisternas (1) Matías Carvajal (1) Bladimir Saldaña (1) Mario Guerra (1) GEOLOGIC EVIDENCE OF THE LARGEST HISTORICAL TSUNAMI OF METROPOLITAN CHILE CONSTRAINS TSUNAMI HAZARD IN THE COUNTRY´ S MOST POPULATED COAST A B S T R A C T The coast of metropolitan Chile has not experienced a large tsunami for nearly three centuries, leading to a perception of tsunami immunity among the population. However, the effects of the 1730 central Chile tsunami challenge this perception. Here, we report geologic evidence of the great 1730 tsunami and contextualize it with the seismic history and tectonic setting of metropolitan Chile. Our findings help to constrain tsunami hazard on the country's most populated coast. Due to the region’s recent seismic past, the community living along the coast of metropolitan Chile shares a risky perception of tsunami immunity (Zamora et al., 2020). Although the adjacent coasts, both to the south and to the north, have recently experiencedmajor tsunamis triggered by large earthquakes, in 2010 and 2015, the sandwiched metropolitan coast has not in nearly three centuries. The last three big metropolitan earthquakes, in 1822, 1906 and 1985, although very destructive, triggered small tsunamis (Lomnitz, 1970; Comte et al., 1986; Carvajal et al., 2017a). However, the effects of a poorly witnessed and understood event in 1730, affecting what was then a sparsely populated area, challenge the immunity perception in what is now the country´s most populated coast.