Recognition and characterisation of the sedimentary facies deposited by the 1960 tsunami in the Maullín estuary, Chile.

Abstract

The tsunami triggered by the earthquake of May 22, 1960, flowed violently into the Maullín River estuary. According to eyewitnesses, the tsunami deposited a widespread sand layer throughout the estuarine marshes. The aim of this study was to determine whether the sand sheet was incorporated into the estuarine stratigraphy. A sedimentological analysis of the sand, located on a saltmarsh opposite Maullín, was carried out. The sand layer was found between the 1960 saltmarsh and the present soil. Considering the sand sheet grain size characteristics and tilt of the buried vegetation, it is probable that the sand was transported from the neighboring dunes and/or sandbars located in the estuary mouth. The spatial distribution of granulometric parameters shows that the marsh vegetation reduced the wave transport capacity during seawater run-up. This illustrates the importance of estuarine marshes in diminishing the impact of tsunamis.