Constraints on the stress state of the San Andreas Fault with analysis based on core and cuttings from San Andreas Fault Observatory at Depth (SAFOD) drilling phases 1 and 2
Constraints on the stress state of the San Andreas Fault with analysis based on core and cuttings from San Andreas Fault Observatory at Depth (SAFOD) drilling phases 1 and 2
复制标题
基于圣安德烈亚斯断层深度观测站 (SAFOD) 钻探第 1 阶段和第 2 阶段的岩心和岩屑分析对圣安地列斯断层应力状态的约束
DOI：
10.1029/2009jb000818
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发表时间：
2010
影响因子：
--
通讯作者：
T. Wong
中科院分区：
文献类型：
--
作者：
S. Tembe;D. Lockner;T. Wong
[1]对现场数据的分析使不同的研究人员得出结论，圣安德烈亚斯断层（SAF）要么具有非常低的摩擦滑动强度（μ 0.6）。SAF的明显弱点的论点通常取决于概念模型，涉及内在薄弱的断层泥或断层带内的孔隙压力升高。一些模型断言，弱断层泥和/或高孔隙压力存在于静态条件下，而其他人认为强度损失或流体压力增加，由于快速同震断层滑动。本文共分三个部分。首先，我们开发了基于Rice（1992）断层带模型的广义方程，将应力方向和大小与深度相关的摩擦系数和孔隙压力联系起来。其次，我们提出了温度和压力相关的摩擦测量从圣安德烈亚斯断层观测站在深度（SAFOD）第1阶段的核心样品和弱矿物与圣安德烈亚斯断层提取的富含伊利石的断层泥。第三，根据SAFOD钻孔数据施加的新约束，我们重新评估了圣安德烈亚斯断层的应力状态。纯滑石（μ C 0.1）的强度最低，足以满足弱断层热流和应力方向约束与静水孔隙压力。其他断层泥的强度随着温度和压力的增加而系统地增加。在这种情况下，热流和应力方向的限制将需要提高孔隙压力，在某些情况下，断层带孔隙压力超过垂直应力。
[1] Analysis of field data has led different investigators to conclude that the San Andreas Fault (SAF) has either anomalously low frictional sliding strength (μ 0.6). Arguments for the apparent weakness of the SAF generally hinge on conceptual models involving intrinsically weak gouge or elevated pore pressure within the fault zone. Some models assert that weak gouge and/or high pore pressure exist under static conditions while others consider strength loss or fluid pressure increase due to rapid coseismic fault slip. The present paper is composed of three parts. First, we develop generalized equations, based on and consistent with the Rice (1992) fault zone model to relate stress orientation and magnitude to depth-dependent coefficient of friction and pore pressure. Second, we present temperature- and pressure-dependent friction measurements from wet illite-rich fault gouge extracted from San Andreas Fault Observatory at Depth (SAFOD) phase 1 core samples and from weak minerals associated with the San Andreas Fault. Third, we reevaluate the state of stress on the San Andreas Fault in light of new constraints imposed by SAFOD borehole data. Pure talc (μ≈0.1) had the lowest strength considered and was sufficiently weak to satisfy weak fault heat flow and stress orientation constraints with hydrostatic pore pressure. Other fault gouges showed a systematic increase in strength with increasing temperature and pressure. In this case, heat flow and stress orientation constraints would require elevated pore pressure and, in some cases, fault zone pore pressure in excess of vertical stress.
影响因子：
3.7
作者：
T. Wiersberg;J. Erzinger
通讯作者：
T. Wiersberg;J. Erzinger