Extreme Sea Surges, Tsunamis and Pluvial Flooding Events during the Last ~1000 Years in the Semi-Arid Wetland, Coquimbo Chile

Karen Araya,Laurent Dezileau,Práxedes Muñoz,Paola Cardenas,Marco Salamanca,Rodrigo Campos-Caba,Lorena Rebolledo,Antonio Maldonado

doi:10.3390/geosciences12030135

Abstract

The coast of Chile has been exposed to marine submersion events from storm surges, tsunamis and flooding due to heavy rains. We present evidence of these events using sedimentary records that cover the last 1000 years in the Pachingo wetland. Two sediment cores were analyzed for granulometry, XRF, pollen, diatoms and TOC. Three extreme events produced by marine submersion and three by pluvial flooding during El Niño episodes were identified. Geochronology was determined using a conventional dating method using 14C, 210Pbxs and 137Cs). The older marine event (E1) was heavier, identified by a coarser grain size, high content of seashells, greater amount of gravel and the presence of two rip-up clasts, which seems to fit with the tsunami of 1420 Cal AD. The other two events (E3 and E5) may correspond to the 1922 (E3) tsunami and the 1984 (E5) storm waves, corroborated with a nearshore wave simulation model for this period (SWAM). On the other hand, the three flood events (E2, E4, E6) all occurred during episodes of El Niño in 1997 (E6), 1957 (E4) and 1600 (E6), represented by layers of fine-grain sands and wood charcoal remains.

Highlights

Licensee MDPI, Basel, Switzerland.Chile has been frequently affected by extreme telluric events such as large-scale earthquakes and tsunamis or extreme meteorological events such as storms and heavy rains
Sediment cores PT1 (50 cm long) and PT4 (47 cm long), were obtained in 2014 in the Pachingo wetland at ~850 m and 920 m from the coastline, respectively—an area currently flooded by tsunamis [1] (Figure 1)
The pluvial flood facies are characterized by a high content of organic carbon with a low lithic fragment content (

Summary

Introduction

Chile has been frequently affected by extreme telluric events such as large-scale earthquakes and tsunamis or extreme meteorological events such as storms and heavy rains. The latest significant extreme telluric events are (i) three more significant earthquakes: in Valdivia in 1960, with a magnitude of 9.5◦ Mw; (ii) in El Maule in 2010, with a magnitude of 8.8◦ Mw; and (iii) in Illapel in 2015, with a magnitude of 8.3◦ Mw. In all cases, a tsunami occurred a few minutes later [1–6]. The one that has caused the most human and economic published maps and institutional affil-. Losses is the 1960 tsunami, in Chile alone, it caused the death of 1700 people, 3000 wounded, 2,000,000 homeless victims. Reflecting in an economic loss of 550 million dollars (CIGIDEN: Centro de Investigación para la Gestión Integrada del Riesgo de Desastres/Chile).

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