A 400‐Year Sediment Record of Tsunamis in Qi'ao Island, Centered at Guangdong‐Hong Kong‐Macao Greater Bay Area

Abstract Identifying tsunamis and determining inundation extent is critical for coastal hazard assessment. We identify potential tsunami deposits in the Guangdong‐Hong Kong‐Macao Greater Bay Area that occurred in 1555 ± 135 CE using a multidisciplinary approach. The inverted 14 C ages of organic matter in sediments, consistent dating of shells, and increased coarse‐grained content imply that a rapid, high‐energy event occurred in the Greater Bay Area. The presence of shell fossils, bimodal grain size distributions, the absence of laminar textures, and an increased concentration of the marine‐derived biomarker brassicasterol in the sediment sequence collectively suggest that these sediments are likely deposits from a tsunami. Tsunami simulations further indicate that larger earthquakes from the Manila Trench could be responsible for this tsunami in the Greater Bay Area. Our findings provide preliminary evidence that tsunamis may be a critical natural hazard concern for the densely populated Greater Bay Area.