Coseismic dehydroxylation in clay minerals and implications for fault weakening during earthquakes

点击翻译按钮获取中文摘要

To elucidate that released water from clay mineral affects dynamic fault weakening and energetics during earthquakes, I first made experimental determinations of the kinetic parameters of the dehydroxylation reaction of illite-muscovite as representative components in the fault gouges, and measured the specific heat capacity and thermal diffusivity. I performed numerical analyses of dynamic fault weakening, taking into account the dehydroxylation reaction of illite on the basis of our experimental results. I clarify that released fluids assist in the pressurization of pore fluid and subsequently induce a decrease in effective normal stress on faults, and that the dehydroxylation reaction takes up heat from the energy released on the fault during earthquake slip. This effect, which inhibits the rise in temperature in the fault, may be significant in clay-rich faults such as subduction boundary faults.