Proxy-based reconstructions of earthquakes and tsunamis at Quidico, South-Central Chile
We utilized geomorphic, microfossil, sedimentological, and stratigraphic methods to investigate the paleotsunami history at Quidico, Chile (38.1° S, 73.2° W). A combination of pits, cores, and riverbank exposures provide stratigraphic evidence of 8 sand layers at Quidico, including tsunami deposits from 2010 and 1960. The sands are laterally continuous but display landward thinning, disappearing completely from the stratigraphy 1.2 km inland from the coast. Intervening sediment layers consist of organic-rich silts and peat. Grain size analysis shows the sand units are bimodal in distribution whereas the organic-rich silts and peat have a broader, bimodal distribution. Lithological analysis showed similarities among all units. Preliminary microfossil analysis indicates a slightly more marine diatom assemblage in the 1960 deposit than in the organic-rich silt units above and below it, indicating a marine incursion. AMS radiocarbon dates of units below each sand layer reveal at least a 600-yr history of tsunami deposition at Quidico.
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