Solid Earth Sciences (S)
Session Sub-category Complex & General(CG)
Session ID S-CG46
Title Uncovering stress accumulation and fault strengthening of megathrust earthquakes
Short Title Stress and Strengthening in Megathrust
Main Convener Name Shuichi Kodaira
Affiliation Japan Agency for Marine-Earth Science and Technology
Co-Convener 1 Name Kohtaro Ujiie
Affiliation Faculty of Life and Environmental Sciences, University of Tsukuba
Co-Convener 2 Name Tatsuya Kubota
Affiliation National Research Institute for Earth Science and Disaster Resilience
Co-Convener 3 Name Ryota Hino
Affiliation Graduate School of Science, Tohoku University
Session Language
E
Scope
In the 2011 Tohoku-Oki Earthquake, large fault slips exceeding 50 meters were observed near the trench axis, an area previously thought to experience stable sliding or aseismic slip during an earthquake cycle. Various methods, including geophysical surveys, observations, ocean drilling, experiments, and simulations, have been employed to clarify the mechanisms behind these shallow, large fault slips. However, the state of fault locking before and between earthquakes - critical to understanding fault slip - remains unclear. To answer this question based on data from the Tohoku-Oki and inland earthquakes, as well as theoretical and model studies, two contrasting hypotheses have been proposed: one suggests that mechanical locking in the shallow part of the plate boundary rapidly progresses after an earthquake, while the other posits that the shallow part remains mechanically unlocked throughout an earthquake cycle. A unified view on this issue has not yet been established. This session aims to address the fundamental problem in the earthquake generation process: how fault strength recovers and stress accumulates along the source fault of a subduction seismogenic zone. We also hope to use the session as an opportunity to share new knowledge about the geophysical and geological structure of the source faults of megathrust earthquakes, and their spatial variation along and across the subduction zone. We invite research presentations from a wide range of fields, including geophysics, geodesy, geology, petrology, geochemistry, drilling science, and both model and theoretical researches, with a focus on subduction seismogenic zones worldwide.
Presentation Format Oral and Poster presentation
Joint Session with AGU ,EGU
Invited Authors Marianne Conin (GeoRessources lab / University of Lorraine)
Christine Regalla (Northern Arizona University)
Fumiaki Tomita (International Research Institute of Disaster Science, Tohoku University)
Matthew W Herman (California State University Bakersfield)
Time Presentation No Title Presenter
Oral Presentation May 26 AM1
9:00 - 9:15 SCG46-01 From JFAST to JTRACK: Investigating the Spatiotemporal Evolution of the Japan Trench Tsunamigenic Fault Shuichi Kodaira
9:15 - 9:30 SCG46-02 Stress estimation on the Japan Trench Plate Boundary Fault 13 years after the 2011 Tohoku-oki Earthquake Marianne Conin
9:30 - 9:45 SCG46-03 IODP Exp 405 reveals how to form a chaotic accretionary prism in the ‘non-accretionary’ Tohoku margin Christine Regalla
9:45 - 10:00 SCG46-04 Lithological overview of IODP Expedition 405 (JTRACK) Site C0019 and C0026 Asuka Yamaguchi
10:00 - 10:15 SCG46-05 Subduction of Horst-and-Graben Structures and Their Impact on Plate Boundary Faults: Numerical and Drilling Perspectives Ayumu Miyakawa
10:15 - 10:30 SCG46-06 Structural characteristics of Japan Trench plate boundary and splay fault zones in the region of shallow coseismic slip Kohtaro Ujiie
Oral Presentation May 26 AM2
10:45 - 11:00 SCG46-07 Structural Characteristics of frontal prism at C0019, recovered by IODP Exp. 405 Yuzuru Yamamoto
11:00 - 11:15 SCG46-08 Hydrogeology of the frontal prism near the Japan Trench revealed by geochemical analyses of IODP Expedition 405 Tsuyoshi Ishikawa
11:15 - 11:30 SCG46-09 Postseismic deformation of the 2011 Tohoku earthquake: Insights from GNSS, GNSS-A, and repeating earthquake observations Fumiaki Tomita
11:30 - 11:45 SCG46-10 Constraining Megathrust Coupling in the Shumagin Gap Region of the Aleutian Subduction Zone Matthew W Herman
11:45 - 12:00 SCG46-11 Uncovering rupture mechanics and tsunami generation of the Tohoku-Oki earthquake using in-situ seafloor pressure gauges Tatsuya Kubota
12:00 - 12:15 SCG46-12 Uncovering mechanism of massive shallow coseismic slip without significant stress drop in 2011 Ryota Hino
Presentation No Title Presenter
Poster Presentation May 26 PM3
SCG46-P01 Paleoseismological record around the JTRACK site, Japan Trench Toshiya Kanamatsu
SCG46-P02 Prism structure around the shallow rupture zone of 2011 Tohoku earthquake: Initial results of IODP JTRACK Exp.405 diatom biostratigraphy Masao IWAI
SCG46-P03 Preliminary results of radiolarian biostratigraphy from IODP Expedition 405 JTRACK Minori Hagino
SCG46-P04 Well and seismic reflection data integration/correlation at JTRACK drill sites Yasuyuki Nakamura
SCG46-P05 Distinguishing Seismic and Landslide-Induced MTDs: Imaging and Machine Learning M Rene Castillo
SCG46-P06 Depth-Temporal Strength profile of the shallow part of the Japan Trench plate boundary through analytical processing of drilling parameters Yohei Hamada
SCG46-P07 Poro-viscoelastic properties of Nankai accretionary prism materials: Lab Measurement, Modeling, and Upscaling Hiroki Sone
SCG46-P08 Microfabric variation in sediments associated with initial subduction processes across the Japan Trench (IODP Exp. 405) Takeru Yoshimoto
SCG46-P09 Changing rock magnetic properties driven by subduction processes recorded in paleomagnetic signatures Taizo Uchida
SCG46-P10 Submarine Fissures in the Accretionary Prism Offshore Taiwan: Evidence of Extensional Deformation Tzu-Ting Chen
SCG46-P11 The Impact of Hydrothermal Circulation on Megathrust Earthquake in Subduction Zones Jae Hoon Lee
SCG46-P12 Stress Changes Effects on Mentawai Segment of Sumatra Megathrust Seismic Gap for Seismic Hazard Assessment Fermiro Faza Haribowo
SCG46-P13 Analysis of slip propagation in a simple shear field using super/sub-loading surface friction model considering temporal adhesion transition of the sliding surface Ryo Yasuike