202510-16 ワシントン大学（UW）
Web要約 の発言：
This map shows Anegada relative to the Puerto Rico Trench, where the Caribbean and North American plates meet. It includes the path of three recent hurricanes to show why it was difficult for the researchers to determine what moved the coral.Atwater et al./Geophysical Research Letters
＜関連情報＞
- https://www.washington.edu/news/2025/10/16/coral-left-by-tsunami-warns-caribbean/
- https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2024GL114448
カリブ海のサンゴにおけるウラン系列分析法を用いた中世津波の年代測定 Dating a Medieval Tsunami With Uranium-Series Techniques on Caribbean Corals
K. Halimeda Kilbourne, Jennifer Weil-Accardo, Nathalie Feuillet, Pierre Deschamps, Yuan-yuan Xu, Chuan-Chou Shen, Hailong Sun, Robert B. Halley, Brian F. Atwater
Geophysical Research Letters Published: 08 October 2025
DOI:https://doi.org/10.1029/2024GL114448
Abstract
Uranium-series dates from coral boulders constrain the timing of a medieval tsunami from the Puerto Rico Trench. Previously reported evidence for this tsunami includes hundreds of coral boulders that came to rest hundreds of meters inland on Anegada, British Virgin Islands. New U-series dates on these coral boulders provide limiting dates for the tsunami. The narrowest limits were by dating interior bands of a coral that retains the hemispherical form of a living coral colony, and which include adjustments for the number of annual density band couplets between the dated samples and the boulder exteriors. By those limits, the tsunami dates between 1381 and 1391 CE, and likely occurred during summer or fall. The tsunami is important as the only reported sign that the eastern Puerto Rico Trench has produced a great earthquake. The dating may aid in defining the earthquake source and in communicating tsunami hazards.
Plain Language Summary
A tsunami flooded islands in the northern Lesser Antilles during the last centuries before Columbus. It is the only known example of a tsunami caused by faulting in the Puerto Rico Trench. The tsunami killed corals on the low-lying island of Anegada by stranding them hundreds of meters inland. Coral skeletons incorporate uranium from seawater, which decays to thorium. This radioactive decay enables dating of young coral skeletons to the nearest few years. Here we use this established dating method to bracket the time of the tsunami between the Common Era years 1381–1391. The dating may aid in searching for accounts of corresponding flooding in the British Isles, and it can be applied to communicating tsunami hazards in the Caribbean.
Key Points
- Uranium-series analyses provide dates for 15 annually banded coral skeletons on the low Caribbean island of Anegada
- A subset of the corals was likely washed ashore in a Puerto Rico Trench tsunami that was previously dated to the 14th or 15th century CE
- U-series dates from a well-preserved coral with a life-like exterior date the tsunami to 1381–1391, probably during a summer or fall
