Holocene Tephrostratigraphy in the East Sea/Japan Sea: Implications for Eruptive History of Ulleungdo Volcano and Potential for Hemispheric Synchronization of Sedimentary Archives

Active volcanoes in East Asia pose potential threats to the surrounding areas. The eruptive history of many of the Japanese volcanoes are well understood, but their dispersal pathways are often based on visible tephra. Additionally, other important volcanoes in the region still require a deeper understanding of their eruptive potential. Here, we explore the Holocene cryptotephra record preserved in a marine core 13PT-P4 in the southwestern East Sea, in order to better reconstruct past eruptive events and their dispersal. Six widespread tephra layers are identified and correlated to their source volcanoes in S Korea (Ulleungdo), China/N Korea (Changbaishan) and Japan (Kikai), with their dispersal ranges updated. Our results rank the 13PT-P4 sequence the most intensively tephra-constrained Holocene record in the East Sea, which permits synchronization of this mid-latitude archive with records in the Arctic and tropical regions. Terrestrially based tephra ages are used to constrain the marine reservoir effect and the age-depth model of the record. The average reservoir age in the region is estimated to be 1150 +/- 30 C-14 yr at ca. 7.3-5.6 cal ka BP and 1565 +/- 30 C-14 yr at ca. 1.0 cal ka BP. These observed changes in reservoir age could indicate active upwelling at a regional scale. Additionally, we provide a detailed age estimate and glass geochemistry for a previously poorly understood eruption (U-1) from the Ulleungdo volcano, thus refining its Holocene eruptive history. The U-1 eruption is dated to 3354-3080 cal yr BP (95.4%), and has glass composition that is distinct from other Ulleungdo tephras.

Automated summary

Researchers reconstructed the eruptive history and dispersal of volcanoes in East Asia using cryptotephra records preserved in a marine core. They identified six widespread tephra layers and correlated them to their source volcanoes in South Korea, China/North Korea, and Japan, updating their dispersal ranges. The study found that the marine core provides the most intensively tephra-constrained Holocene record in the East Sea, allowing for synchronization with records in other regions.