Geological record of thermal pressurization and earthquake instability of subduction thrusts
Geological record of thermal pressurization and earthquake instability of subduction thrusts
复制标题
DOI：
10.1016/j.tecto.2010.01.002
复制
发表时间：
2010-04
期刊：
影响因子：
2.9
通讯作者：
K. Ujiie;M. Kameyama;A. Yamaguchi
中科院分区：
文献类型：
--
作者：
K. Ujiie;M. Kameyama;A. Yamaguchi
在地震中，断层强度随着滑动减弱距离Dc的减小而减小，直至残余强度。地震过程中断层不稳定性评价的关键是离散度的估计。然而，从自然断层中确定dc一直很困难。我们从发震深度发掘出的俯冲逆冲的陆地模拟物中发现了热增压的地质证据；热加压表现为粉碎物料的流态化和摩擦加热引起的流体包裹体体积的增加。在地震滑动带厚度、摩擦加热温度范围和俯冲逆冲环境条件约束下的热增压数值分析表明，俯冲逆冲断层的深度范围为0.03 ~ 0.22m，与初始孔隙流体压力无关。热增压对俯冲逆冲的影响表明，俯冲地震发生时应力释放迅速，辐射能量高。
During an earthquake, fault strength decreases with slip over the slip-weakening distance, Dc, to a residual strength. The estimation of Dcis crucial for the evaluation of fault instability during earthquakes; however, it has been difficult to determine Dcfrom natural faults. We found geological evidence of thermal pressurization from the on-land analog of a subduction thrust exhumed from seismogenic depths; thermal pressurization was indicated by the fluidization of comminuted material and increase in the volume of fluid inclusions by frictional heating. Numerical analysis of thermal pressurization with the constraints on the thickness of the seismic slip zone, the temperature range of frictional heating, and ambient conditions of subduction thrusts indicates that the Dcof subduction thrusts ranges from 0.03 to 0.22m, which is independent of initial pore-fluid pressure on subduction thrusts. The short Dcassociated with the effect of thermal pressurization on subduction thrusts indicates the occurrence of rapid stress relief and high radiated energy during subduction earthquakes.