Data relates to the NERC Urgency Grant NE/R00210X/1 which focusses on Sediment signatures of the 25 December 2016 Chile earthquake to constrain detection limits of tidal marsh records. The documentation provides an overview of findings from two field seasons to the southern coast of Isla de ChiloƩ, Chile, including field observations, sediment samples and surface vegetation surveys. The research locations for diatom analyses are Ayentema, Asasao, Inio and Quilanlar, southern ChiloƩ, Chile. Field season 1 (excluding travel dates): 2-9 August 2017 Field season 2 (excluding travel dates): 6-16 October 2017 Diatom data collection: through to 30 June 2018