A widespread meter-thick turbidite in the Southern Kuril trench records the 13th-century megathrust earthquake

Abstract A meter-thick deposit preserved in five piston cores along the southern Kuril Trench provides evidence of an extensive turbidite, interpreted to result from a giant megathrust earthquake in the thirteenth century. The emplacement age of this thick turbidite is determined to be 719–672 years BP based on high-resolution age–depth models constructed from paleomagnetic secular variation data and anchored by a regionally correlated tephra layer and calibrated radiocarbon dates. When accounting for the uncertainty introduced by the smoothing of paleomagnetic data, the modeled age range expands to 752–620 years BP. Nevertheless, both age intervals closely match that of widespread seismogenic tsunami deposits along the Hokkaido coast, supporting the interpretation of a shared trigger of the 13th-century megathrust earthquake. Lateral correlations and volume estimates indicate the deposit extends 100–150 km along the trench axis, with a total volume exceeding 1,700 million m3. Magnetic fabric patterns, along with spatial variations in sedimentary structures and textures, indicate that the main turbidity current entered the trench via the Kushiro Canyon and propagated bilaterally along the trench axis. This study presents the first offshore evidence of a margin-scale turbidite from the > 7000 m-deep Kuril Trench, strengthening land–sea correlations for the 13th-century earthquake and demonstrating the broader applicability of PSV-based chronostratigraphy in ultra-deep trench environments globally.