14:30 〜 14:45
[SCG45-52] Dynamic Strength and Fracture Energy of Rocks at Extreme Strain Rates: Insights into Seismic Energy Dissipation in Fault Zones
キーワード：粉砕岩、衝突実験、地震のエネルギー収支、断層破砕帯
This study examines how seismic energy dissipates within the damage zone surrounding a fault core, a process increasingly recognized as critical based on numerical simulations (e.g., Okubo et al., 2018JGR) and field studies of pulverized rocks (e.g., Muto et al., 2015GRL). It highlights the essential role of rock fracturing in the damage zone in modulating rupture propagation along the main fault, which in turn influences seismic damages. However, precise quantification of this dissipation process has remained challenging due to the limited availability of data on the dynamic strength of damaged rocks and the rarity of pulverized rocks in certain strike-slip faults (see recent review by Johnson et al., 2018).
To overcome these limitations, we conducted high-strain-rate rock deformation experiments to assess the mechanical properties of fault zone rocks under extreme conditions (Jayawickrama et al., 2023). Our findings suggest that the dynamic strength of these rocks is substantially greater than previously assumed and follows a predictable relationship with strain rate, which can be mathematically expressed through a unified equation. Additionally, we propose a novel analytical approach—the "seismic energy meter"—which links the fractal dimension of fault rocks to their fracture energy at high strain rates. By analyzing the particle size distribution of fault materials, this method provides a robust framework for estimating the energy dissipated during rock fragmentation in fault zones.
Ultimately, this research advances our understanding of seismic energy dissipation mechanisms, offering new perspectives for evaluating earthquake hazards and the mechanical behavior of fault systems.
References
Jayawickrama, E, G., Sekiguchi, T., Muto, J., Sawa, S., Nagahama, H., Kono, Y., Bae, K-O., Shin, H-S., 2023, A split Hopkinson pressure bar for experimental investigation of dynamic pulverization under very high strain rates, Rev. Sci. Instrum., 94, 085110. https://doi.org/10.1063/5.0151448.
Johnson, S. E., Song, W. J., Vel, S. S., Song, B. R., & Gerbi, C. C. 2021, Energy partitioning, dynamic fragmentation, and off-fault damage in the earthquake source volume. Journal of Geophysical Research: Solid Earth, 126, e2021JB022616. https://doi. org/10.1029/2021JB022616.
Muto, J., Nakatani, T., Nishikawa, O., Nagahama, H., 2015, Fractal particle size distribution of pulverized fault rocks as a function of distance from the fault core. Geophys. Res. Lett., 42, 3811–3819. https://doi.org/10.1002/2015GL064026.
Okubo, K., Bhat, H. S., Rougier, E., Marty, S., Schubnel, A., Lei, Z., et al. 2019, Dynamics, radiation, and overall energy budget of earthquake rupture with coseismic off-fault damage. Journal of Geophysical Research: Solid Earth, 124. https://doi.org/10. 1029/2019JB017304
To overcome these limitations, we conducted high-strain-rate rock deformation experiments to assess the mechanical properties of fault zone rocks under extreme conditions (Jayawickrama et al., 2023). Our findings suggest that the dynamic strength of these rocks is substantially greater than previously assumed and follows a predictable relationship with strain rate, which can be mathematically expressed through a unified equation. Additionally, we propose a novel analytical approach—the "seismic energy meter"—which links the fractal dimension of fault rocks to their fracture energy at high strain rates. By analyzing the particle size distribution of fault materials, this method provides a robust framework for estimating the energy dissipated during rock fragmentation in fault zones.
Ultimately, this research advances our understanding of seismic energy dissipation mechanisms, offering new perspectives for evaluating earthquake hazards and the mechanical behavior of fault systems.
References
Jayawickrama, E, G., Sekiguchi, T., Muto, J., Sawa, S., Nagahama, H., Kono, Y., Bae, K-O., Shin, H-S., 2023, A split Hopkinson pressure bar for experimental investigation of dynamic pulverization under very high strain rates, Rev. Sci. Instrum., 94, 085110. https://doi.org/10.1063/5.0151448.
Johnson, S. E., Song, W. J., Vel, S. S., Song, B. R., & Gerbi, C. C. 2021, Energy partitioning, dynamic fragmentation, and off-fault damage in the earthquake source volume. Journal of Geophysical Research: Solid Earth, 126, e2021JB022616. https://doi. org/10.1029/2021JB022616.
Muto, J., Nakatani, T., Nishikawa, O., Nagahama, H., 2015, Fractal particle size distribution of pulverized fault rocks as a function of distance from the fault core. Geophys. Res. Lett., 42, 3811–3819. https://doi.org/10.1002/2015GL064026.
Okubo, K., Bhat, H. S., Rougier, E., Marty, S., Schubnel, A., Lei, Z., et al. 2019, Dynamics, radiation, and overall energy budget of earthquake rupture with coseismic off-fault damage. Journal of Geophysical Research: Solid Earth, 124. https://doi.org/10. 1029/2019JB017304