HR: 1330h
AN: S42D-0199    [PDF]
TI: Numerical Study on Multi-Scaling Earthquake Rupture
AU: Ide, S
EM: ide@eps.s.u-tokyo.ac.jp
AF: Department of Earth and Planetary Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033 Japan
AU: * Aochi, H
EM: hideo.aochi@irsn.fr
AF: Institut de Radioprotection et de S\^uret\'e Nucl\'eaire, Bureau d'Evaluation des Risques Sismiques pour la S\^uret\'e des Installations Nucl\'eaires, BP17, Fontenay-aux-Roses, 92262 France
AB: We develop a new numerical scheme using a renormalization and a 3Dboundary integral equation method in order to simulate a multi-scaling dynamic rupture. We are able to simulate how a small earthquake grows up to a large one in spatially heterogeneous field of fracture energy $G_c$ or critical slip-weakening distance $D_c$. We test the case where $D_c$ grows according to a hypocentral distance $L$ ($D_c \propto L^\beta$). This permits rupture to start in the very microscopic scale. When $\beta = 1$, we succeed to numerically show that rupture propagates at a constant rupture speed in a uniform initial stress field. This result still keeps the scaling relation of $G_c$ and $D_c$ inferred for earthquake rupture, but infers that no scale-dependent initial process is required for all size of events. The break in the proportional relation between $D_c$ and $L$ ($\beta \neq 1$) requires to keep energy balance around the rupture front. As a result, we observe that rupture is accelerated up to a speed even faster than the shear wave velocity ($\beta < 1$) or that arrested ($\beta > 1$). These simulations implies that important is the relation $D_c \propto L$ for a self-similar rupture propagation (cascading rupture), a scale-independent constant rupture velocity, and scale-dependent fracture energy $G_c$.
DE: 7209 Earthquake dynamics and mechanics
DE: 7215 Earthquake parameters
DE: 7260 Theory and modeling
SC: Seismology [S]
MN: 2003 Fall Meeting