第104回統計地震学セミナー / The 104th Statistical Seismology Seminar (Hybrid)
- 【Date＆Time】
- 23 December 2025 15:00-16:30
Admission Free, No Booking Necessary - 【Place】
- online (with zoom) and 4F Lounge (ISM)
- Zoom meeting:
https://us06web.zoom.us/j/8304503874?pwd=TkdxT1Z0YXFFWUt1c013eHkydTU2Zz09&omn=85957719381
Meeting ID: 830 450 3874
Passcode: 55338532
Join instructions
https://us06web.zoom.us/meetings/85957719381/invitations?signature=Y7_ua85wl7jpy2kbb5R7hAbdfOSFKLHedj8QKvSU8Fc - 【Speaker】
- Dr. Naidan Yun
(Visiting Researcher at Nagoya University)
- 【Title】
- Extremely Low Megathrust Strength and Shear Stress Reversal during the 2011 Tohoku-Oki Earthquake
- 【Abstract】
- Earthquakes release elastic stress accumulated during tectonic loading, and most models assume partial or complete stress release. In contrast, the over-release mode, where the final shear stress reverses, is rarely observed or discussed, despite its implications for larger magnitudes and longer recurrence intervals. Resolving stress reversal is challenging because of the difficulty in determining absolute stresses. Here, we develop an innovative method to obtain the absolute stress field before the 2011 Tohoku-Oki earthquake using co-seismic focal mechanism rotations. We identify the main slipped region showing significant (46% on average) stress reversal. Numerical simulations suggest that a vast and trench-reaching rupture with low friction led to over-release. This mechanism may be applicable for global megathrust earthquakes, calling for re-evaluation of their seismic hazards.
