[M-GI28] 地球掘削科学

[MGI28-01] IODP Exp 405 JTRACK: Tracking Tsunamigenic Slip Across the Japan Trench

★招待講演

*小平 秀一¹、氏家 恒太郎²、Conin Marianne ³、Regalla Christine⁴、Kirkpatrick James⁵、Fulton Patrick⁶、前田 玲奈¹、奥津 なつみ¹、江口 暢久¹、IODP Exp.405 Science Party (1.海洋研究開発機構、2.University of Tsukuba、3.University of Lorraine、4.Northern Arizona University、5.University of Nevada、6.Cornell University)

キーワード：Tohoku-oki earthquake、 Japan Trench、 seismogenic fault、 IODP

The 2011 Mw9.1 Tohoku-oki earthquake caused an extraordinary slip along the shallow section of the Japan Trench, leading to a catastrophic tsunami. In response, the 2012 JFAST expedition retrieved fault zone core samples and conducted logging-while-drilling and temperature measurements, which provided key insights into the fault zone structure/materials, slip behavior, and stress changes. However, its ability to capture the fault’s spatiotemporal changes was limited. In 2024, IODP Expedition 405 (JTRACK) was carried out to address these challenges by revisiting and further exploring the Japan Trench. At Site C0019 (~6 km landward of the trench), coring and logging operations were conducted to examine the long-term physical and structural evolution of the fault. Additionally, borehole observatories were deployed to collect extended temperature and pressure data within the seismogenic zone. Meanwhile, at Site C0026 (~8 km seaward), investigations focused on the properties of incoming sediments before they are subducted, shedding light on the factors influencing fault slip. In addition to scientific investigations, JTRACK also focused on public engagement. Outreach teams aboard the vessel hosted live interactions, educational initiatives, and media events to convey the importance of ocean drilling and its role in understanding earthquake hazards. These efforts significantly enhanced understanding of subduction zone processes among diverse audiences. This presentation will outline JTRACK’s mission, implementation, and findings, emphasizing its role in deepening our comprehension of the dynamic processes governing subduction zone earthquakes.