In situ measurement of the hydraulic diffusivity of the active Chelungpu Fault, Taiwan
In situ measurement of the hydraulic diffusivity of the active Chelungpu Fault, Taiwan
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DOI：
10.1029/2006gl026889
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发表时间：
2006-08-30
影响因子：
5.2
通讯作者：
Ma, K. F.
中科院分区：
文献类型：
--
作者：
Doan, M. L.;Brodsky, E. E.;Ma, K. F.
水力扩散率控制流体压力，从而影响破裂过程中的有效正应力。模型表明，在M-W = 7.6 1999年集集地震流体加压时，加压可能会减少在大的滑动，如果故障是充分密封的地区的高频震动一个特别壮观的例子。通过跨孔实验，对模型中的关键参数--原位水力扩散率进行了研究。我们发现扩散系数D =（7 +/- 1）× 10（-5）m（2）/s，这是一个与地震期间车笼埔断层增压相适应的低值。在大多数多孔弹性介质中，水力储存系数S在10（-7）和10（-5）之间，因此沿着断裂带的渗透率T在10（-11）m（2）/s和10（-9）m（2）/s之间。相应的渗透率（10（-18）-10（-16）m（2））最多比从寄主岩石的岩心样品上获得的值大100倍。断裂带超压0.06 ~ 6 MPa，为岩石静压力的0.2%~ 20%。
Hydraulic diffusivity controls fluid pressure and hence affects effective normal stress during rupture. Models suggest a particularly spectacular example of fluid pressurization during the M-w = 7.6 1999 Chichi earthquake when pressurization may have reduced high-frequency shaking in the regions of large slip if the fault was sufficiently sealed. We investigate in situ hydraulic diffusivity which is the key parameter in such models through a cross-hole experiment. We find a diffusivity of D = ( 7 +/- 1) x 10(-5) m(2)/s, which is a low value compatible with pressurization of the Chelungpu fault during the earthquake. In most poroelastic media, the hydraulic storativity S lies between 10(-7) and 10(-5), so that the transmissivity T along the fault zone is comprised between 10(-11) m(2)/s and 10(-9) m(2)/s. The corresponding permeability (10(-18) - 10(-16) m(2)) is at most one hundred times larger than the value obtained on core samples from the host rock. The fault zone is overpressurized by 0.06 to 6 MPa, which is between 0.2% and 20% of the lithostatic pressure.