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The eruptive histories of Ulleungdo (South Korea) and Changbaishan (North Korea/China border) volcanoes are not well constrained since their proximal stratigraphies are poorly exposed or largely inaccessible. However, determining the past behaviour of these volcanoes is critical since future eruptions are likely to disperse ash over some of the world’s largest metropolitan regions. Alkaline tephra deposits erupted from both centres are routinely identified in marine cores extracted from the Sea of Japan, as well as high-resolution lacustrine records east of the volcanoes. Here, we review the distal ash occurrences derived from Ulleungdo and Changbaishan and provide new data from the Lake Suigetsu (central Honshu, Japan) sediment core, in order to provide a more complete and constrained eruption framework. The intensely-dated Lake Suigetsu archive provides one of the most comprehensive distal eruption records for both centres, despite being located ca. 500 km E of Ulleungdo and ca. 1000 km SSE of Changbaishan. The Suigetsu record is utilised to precisely date and geochemically fingerprint (using major, minor and trace element glass compositions) ash fall events that reached central Honshu. Here, we identify a new non-visible (cryptotephra) layer in the Suigetsu sediments, which reveals a previously unreported explosive event from Changbaishan at 42,750 – 42,323 IntCal13 yrs BP (95.4 % confidence interval). This event is chronologically and geochemically distinct from the B-J (Baegdusan-Japan Basin) tephra reported in the Sea of Japan (ca. 50 ka). Furthermore, we also confirm that the widespread U-Ym tephra erupted from Ulleungdo reached central Japan, and is herein dated to 40,332 – 39,816 IntCal13 yrs BP (95.4 % confidence interval). This terrestrial 14C-derived age of the U-Ym can be used to constrain the chronology of marine records containing the same marker layer. This reviewed and integrated tephrostratigraphic framework highlights the pivotal role that distal sedimentary records can play in evaluating the eruptive histories and hazard potential of Ulleungdo and Changbaishan.

The eruptive histories of Ulleungdo (South Korea) and Changbaishan (North Korea/China border) volcanoes are not\ud well constrained since their proximal stratigraphies are poorly exposed or largely inaccessible. However, determining\ud the past behaviour of these volcanoes is critical since future eruptions are likely to disperse ash over some of the\ud world’s largest metropolitan regions. Alkaline tephra deposits erupted from both centres are routinely identified in\ud marine cores extracted from the Sea of Japan, as well as high-resolution lacustrine records east of the volcanoes.\ud Here, we review the distal ash occurrences derived from Ulleungdo and Changbaishan and provide new data from the\ud Lake Suigetsu (central Honshu, Japan) sediment core, in order to provide a more complete and constrained eruption\ud framework. The intensely-dated Lake Suigetsu archive provides one of the most comprehensive distal eruption\ud records for both centres, despite being located ca. 500 km E of Ulleungdo and ca. 1000 km SSE of Changbaishan.\ud The Suigetsu record is utilised to precisely date and geochemically fingerprint (using major, minor and trace element\ud glass compositions) ash fall events that reached central Honshu. Here, we identify a new non-visible (cryptotephra)\ud layer in the Suigetsu sediments, which reveals a previously unreported explosive event from Changbaishan at 42,750\ud – 42,323 IntCal13 yrs BP (95.4 % confidence interval). This event is chronologically and geochemically distinct from\ud the B-J (Baegdusan-Japan Basin) tephra reported in the Sea of Japan (ca. 50 ka). Furthermore, we also confirm that\ud the widespread U-Ym tephra erupted from Ulleungdo reached central Japan, and is herein dated to 40,332 – 39,816\ud IntCal13 yrs BP (95.4 % confidence interval). This terrestrial 14C-derived age of the U-Ym can be used to constrain\ud the chronology of marine records containing the same marker layer. This reviewed and integrated tephrostratigraphic\ud framework highlights the pivotal role that distal sedimentary records can play in evaluating the eruptive histories and\ud hazard potential of Ulleungdo and Changbaishan.

We, the members of the Division for Chronological Research at the Institute for Space-Earth Environmental Research at Nagoya University, held a regional contribution program for elementary and junior high school students on August 4–5, 2016: “Investigation of past solar activity and the paeloclimate change from tree annual rings and varved lake sediments.” Thirty-five students and six of their parents observed natural samples to experience earth and archaeological sciences. The first day began with a lecture on how tree annual rings and varved lake sediments can be used to reveal the paleoclimate. After the lecture, the students took part in several hands-on experiments on sedimentology. On the second day they travelled to the Wakasa area by bus and visited the Wakasa-Mikata Jomon Museum to learn about the pre-historic Jomon lifestyle and culture by observing remains from the Jomon Period excavated from the Torihama shell mound. Later in the day they took a cruising observation expedition across Suigetsu Lake, Mikatagoko to observe unique varved sediment layers on a lakebed revealing paleoclimate change dating back 70,000 years. Finally, they observed genuine sediment cores at the Fukui Prefectural Satoyama-Satoumi Research Institute. The program ended a success. The post-program questionnaire shows that the participants enjoyed the program and learned many new things., 年代測定研究部においては、平成28年度総長裁量経費地域貢献事業として、平成28年8月4日（木）と5日（金）の2日間に亘り、小学5年生から中学3年生まで35名を対象とした体験学習「樹木年輪・年縞堆積物から過去の太陽活動、地球の古気候を探る」を実施した。初日は名古屋大学で講義・実習を、2日目はバスで福井県若狭三方五湖に出向き、若狭三方縄文博物館の見学、水月湖の野外調査、ならびに福井県里山里海湖研究所において年縞堆積物の見学を行った。全体的に内容を詰めすぎた感はあるが、参加者は楽しみながら体験学習には取り組んでいた。アンケート結果が示すように、本事業の目的である“小・中学生に自然科学・地球科学・文化財科学等の面白さを伝える”ことは十分に果たされ、地域社会へ貢献できたと考えられる。

In 1959, the Conlon report, a presentation of United States government policies in relation to Asian cultures, stated the following about Japanese culture (in a section titled ‘Social change’):Developments within and among the various Japanese social classes suggest the dynamic, changing quality of modern Japan … No area of Japan, moreover, is beyond the range of the national publications, radio, and even TV. New ideas can be quickly and thoroughly disseminated; it is in this sense that Japanese culture can become more standardised even as it is changing. Many of the changes look in the direction of the United States; in such diverse fields as gadgets, popular music, and fashions. American influence is widespread. And this is but one evidence of the general desire to move away from the spartan, austere past toward a more comfortable, convenient future.