A comprehensive review of tsunami and palaeotsunami research in Chile

Abstract

Chile is a tsunami-prone country. Since the 1960 Chilean earthquake triggered a Pacific-wide tsunami, there has been a considerable amount of research conducted on the geologic evidence for tsunamis along the coast of Chile. This review aims to gather all the evidence of tsunami inundation to identify which areas along the coast of Chile have been affected during modern, historical, and prehistoric times. This contributes to assessing the local and regional impacts of past events and helps to identify potential sites for further study. We seek to show the spatial and temporal distribution of tsunami deposits affected by their preservation in different climate zones. We also seek to assess the interpretation of each deposit by comparing information provided from a variety of sources and analyses. The review shows that thirty-one tsunamigenic events have been reported in historic times from 1570 CE to 2015 but deposits have only been found for twelve of these. There are ninety-two palaeotsunami deposits along Chile's coast and these span from the Miocene to Late Holocene. Geological evidence has been reported from fifty-seven sites of which 70% were found in southern Chile. While many deposits were identified in coastal lakes and river floodplains in southern Chile, tsunami deposits in the north are more commonly found on coastal plains, clifftops, and marshes. We also created a table assigning a level of certainty for each deposit. This is developed by the consideration of five criteria that include the use of multiproxy analyses, the correlation of a site with other deposits, comparisons with numerical simulations or historic counterparts, discrimination of the deposit from other possible processes, and a critical evaluation of the data in the original publication. This work provides insight into the types of environments that are most likely to contain evidence of past tsunamis and highlights the potential of finding more evidence in Chile of Pacific-wide “orphan tsunamis,” such as the 1420 CE event that inundated the coast of Japan. Altogether, this review reveals a high frequency of tsunamis on the Chilean coasts and indicates that in some areas ancient tsunamis have reached higher inundations than those reported in the historic record, therefore, these data should be considered in future tsunami modelling to be better prepared for future events.