[J09-2] Geodesy and seismology general contributions II

[J09-2-02] Effect of frictional properties of minerals in the crust on the depth of seismic faulting

^○Koji Masuda (Geological Survey of Japan, AIST, Tsukuba, Japan)

Depth and width of seismogenic zones seem to result from the nature of the friction of materials which form the crust. Frictional properties of materials, which depend on the environmental conditions such as temperature and water content, control the depth which divided between the stable region where earthquakes don't occur and the unstable region where earthquakes take place. For example, laboratory experiments revealed that a small amount of quartz added to the composite materials has a stabilizing effect, resulting the unstable to stable behavior of the mixture materials. Here we measured frictional properties of quartz and feldspar, major minerals of the crustal rocks, under high pressure and high temperature conditions, in order to understand the effects of frictional properties of minerals in the crust on the depth range of seismogenic region. We found that there are temperature ranges correspond to the unstable regions for both quartz and feldspar under the wet condition and that the unstable temperature region of quartz is narrower than that of feldspar. These results suggest that the frictional properties of constituent materials in the crust critically affect the seismic faulting depth and the seismogenic processes.