Discriminating between tsunamis and tropical cyclones in the sedimentary record using X-ray tomography

Scrub Island lagoon (Anguilla, Caribbean) provides the opportunity to display both tropical cyclones, near-field and far-field tsunami deposits within the same sediment core. Here, we use X-ray tomography to highlight the sedimentary fabric and link it to processes that occurred during these events. Overall, the tsunami sedimentary fabric remains highly homogenous, and display fabric trends that can be associated with variations in sediment concentration and/or flow strength. The near-field tsunami deposit displays fabric characteristics of intense and highly-concentrated flow, whereas the far-field tsunami fabric is less defined which may illustrate a less intense event. Contrastingly, the sediment fabric of the tropical cyclone (hurricane) deposit is more variable with a succession of different dipping-angles and orientations of the grains that can be interpreted as the record of successive waves, likely infragravity waves. Observed differences in sedimentary fabrics between tsunami and tropical cyclone-related deposits are an encouragement to generalize sediment fabric parameters as criteria to distinguish them in coastal sedimentary archives.

Automated summary

Using X-ray tomography, this study examines the sedimentary fabric of the Scrub Island lagoon in Anguilla, Caribbean, to understand the processes occurring during tropical cyclones and tsunamis. The fabric of tsunami deposits is highly homogenous, with variations associated with sediment concentration and flow strength. In contrast, the fabric of hurricane deposits shows more variability, potentially indicating successive waves.