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两个最常引述的地震前兆指标是氡放射和电势变化(Wakita,Nakamura and Sano,1988;Igarashi,et al,1995;Virk and Singh,1994;Raleigh,et al,1977;Corwin and Morrison,1977;Varotsos,et al,1993),但已有的少量报道一般被认为是值得怀疑的(Geller,1998;Pham,et al,1998;Morrison,et al,1979;Geller,1997;Wyss,1997)。如果确实存在一种令地壳形变和氧放射或电信号变化相关的机制,则必定有流体参与(Seholz,et al,1973;Igarashi,et al,1992;Roeloffs,1988;Wood,et al,1993;Mizutani,et al,1976;Iouniaux,et al,1995;Bernard,1992;King,1986)。通过研究受控应力状态和水文条件下的天然系统,对这一过程已取得一些初步认识(Perrier,et al,1997)。本文报道了法国阿尔卑斯2个年水位变化超过50m的人工湖附近自1995年以来的氡放射、电势和地形变观测资料。观测结果表明,电势变化、氡放射与包括由水位季节性变化引起的地形变有重复相关性。地形变用偏离预期的弹性变形响应的地表倾斜表示,并与应交加速期相对应,说明加速加载可以提高流体的迁移性。这一行为可以定性地用一模型来解释。该模型认为应变引起流体过压和在裂隙内的动力流。本文观测可以阐明岩石传输特性对形变的敏感性。
The two most commonly cited seismic precursory indicators are radon emission and potential changes (Wakita, Nakamura and Sano, 1988; Igarashi, et al, 1995; Virk and Singh, 1994; Raleigh, et al, 1977; Corwin and Morrison, 1977; Varotsos, et al., 1993), but few reports have been published that are generally considered suspect (Geller, 1998; Pham, et al., 1998; Morrison, et al., 1979; Geller, 1997; Wyss, 1997). Fluid must be involved if there is indeed a mechanism by which crustal deformation is associated with changes in oxygen emissions or electrical signals (Seholz, et al., 1973; Igarashi, et al., 1992; Roeloffs, 1988; Wood, et al., 1993; Mizutani, et al, 1976; Iouniaux, et al, 1995; Bernard, 1992; King, 1986). Some preliminary understanding of this process has been made by studying natural systems under controlled stress conditions and hydrological conditions (Perrier, et al., 1997). This paper reports radon, potential and topography observations of radon near the artificial lake with changes of more than 50 m in the French Alps since 1995. Observations show that there is a recurring correlation between changes in potential and radon emissions, including those caused by seasonal changes in water level. Terrain changes are deviated from expected elastic deformation response of the surface tilt, and with the corresponding acceleration period corresponding, indicating that accelerated loading can improve fluid mobility. This behavior can be qualitatively explained by a model. The model considers strain to cause fluid overpressure and motive flow within the fracture. The observation of this paper can clarify the sensitivity of rock transmission characteristics to deformation.