HR: 11:05h
AN: S12B-04    [Abstracts]
TI: Effects of the Metamorphic Dehydration Reactions on Long-term Slow Slip Events: Implications of two Dimensional Numerical Simulations
AU: * Mitsui, Y
EM: mitsui@kugi.kyoto-u.ac.jp
AF: Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto, Kyoto, 606-8224, Japan
AU: Hirahara, K
EM: hirahara@kugi.kyoto-u.ac.jp
AF: Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto, Kyoto, 606-8224, Japan
AB: To clarify the mechanism of aseismic slow slip events at subduction zones, numerical model calculations using laboratory-derived rate- and state- dependent friction laws have been done heretofore. However, no studies have focused on effects of the metamorphic dehydration reactions in the oceanic crust, which is expected to change pore pressure on the plate interface. Therefore, we execute 2D model calculations taking into account pore pressure conditions reflecting the metamorphic dehydration reactions, which are considered to occur in the deep portion of seismogenic zone close to the transition region from unstable to stable sliding ones. Because the implication of the metamorphic dehydration reactions for pore pressure conditions remains unknown yet, we simply set two contradictory models: (1) the dehydration reactions increase the pore pressure and strengthen the overpressurization, (2) the dehydration reactions decrease the pore pressure and release the overpressurization. As a result of calculation, model (2) is more favorable for causing the aseismic slip events. We can interpret our result that small nucleation is needed to cause aseismic slip events. In addition, our result shows the possibility of a relaxation of overpressurization owing to the dehydration reactions via some factors such as the increasing permeability, or a transition of the frictional parameters to unstable slip regimes.
DE: 7240 Subduction zones (1207, 1219, 1240)
DE: 7290 Computational seismology
SC: Seismology [S]
MN: 2007 Fall Meeting