Comparison of lake and land tephra records from the 2015 eruption of Calbuco volcano, Chile

Abstract

Tephra layers in lake sediment cores are regularly used for tephrostratigraphy as isochronous features for dating and recording eruption frequencies. However, their value for determining volcanic eruption size and style may be complicated by processes occurring in the lake that modify the thickness and grain size distributions of the deposit. To assess the reliability of data from lake cores, we compare tephra deposited on land during the 2015 eruption of Calbuco volcano in Chile to records in sediment cores from three lakes of different sizes that are known to have received primary fall deposits. In general, the thickness and granulometry of the deposit in lake cores and nearby terrestrial sections are very similar. As anticipated, however, cores sampled close to (here, within 300 m of) fluvial inflows were affected by sediment deposition from the lake’s catchment; they differed from primary deposits not only in their greater thickness and organic content but al