PHYSICAL-PROPERTIES OF THE VARIATIONS OF THE ELECTRIC-FIELD OF THE EARTH PRECEDING EARTHQUAKES .1.
PHYSICAL-PROPERTIES OF THE VARIATIONS OF THE ELECTRIC-FIELD OF THE EARTH PRECEDING EARTHQUAKES .1.
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DOI：
10.1016/0040-1951(84)90059-3
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发表时间：
1984-01-01
期刊：
影响因子：
2.9
通讯作者：
ALEXOPOULOS, K
中科院分区：
文献类型：
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作者：
VAROTSOS, P;ALEXOPOULOS, K
在希腊的一个由18个台站组成的网络中，对地震前地球的电场变化进行了研究。这些前兆地震电信号（SES）出现在地震（EQ）前6-115 h，持续时间为1 min ~ 112 h。与其他前兆相比，持续时间和提前时间不依赖于EQ震级（M）。这些信号表现为在两个电极之间测量的电势差的瞬态变化（对于在大约L= 50 m的距离处的电极，高达几毫伏），这取决于M、震中距离r和局部不均匀性。在两个垂直方向（EW和NS）上测量电场分量。实验的总体表明，每个SES的感兴趣的量是电位变化的最大值ΔV。一个即将发生的EQ的SES同时出现在多个台站，而不伴随着磁场的任何显著变化。制定了以下规则：1。(1)在给定台站的单线（例如EW）上记录并从不同地震区发射的地震电信号具有Δ V值，该Δ V值根据1 r定律（对于r = 50 km）随震中距离减小。2. (2)对于给定台站的给定测线，从给定地震区发射的SES（r_（？）具有随幅度增加的Δ V值;在良好的近似下，log ΔV与M的关系给出斜率在0.3和0.4之间的直线。如果对同一测站和测线考虑另一个地震区，则直线平行于前一个，但偏移一个常数，该常数完全取决于震中距离的比值。因此，如果将不同地震区的地震发射量log（ΔV· r）与M作图，则每个台站都呈现出具有相同斜率的唯一线性关系。3. (3)在不同台站记录的给定EQ的同时Δ V值不遵循1 r依赖性。每个方向上的电场值ΔV L除以适当的因子（根据经验确定的有效电阻率），给出了地球中电流密度分量变化的量特征，可以指定为信号的强度该方向。通过组合两个方向的值，得出SES的总强度J。这个量被发现衰减与台站的距离根据1 r-定律，使日志（J· r）是一个唯一的线性函数M的所有台站和地震区。
The electric field variations of the earth that occur before earthquakes have been studied in a network of eighteen stations in Greece. These precursor seismic electric signals (SES) occur 6–115 h before the earthquake (EQ) and have a duration of 1 min to 1 1 2 h. The duration and the lead-time in contrast to other precursors, do not depend on EQ-magnitude (M). These signals appear as a transient change of the potential difference measured between two electrodes (up to a few millivolts for electrodes at a distance of about L= 50 m) depending on M, the epicentral distance r and the local inhomogeneities. The components of electric field are measured in two perpendicular directions (EW and NS). The totality of experiments showed that the interesting quantity of each SES is the maximum value ΔV of the potential change. The SES of an impending EQ appears simultaneously at a number of stations without being accompanied by any significant change in the magnetic field. The following rules have been established: 1.(1) Seismic electric signals recorded on a single line (eg EW) of a given station and emitted from various seismic regions have ΔV-values that decrease with the epicentral distance according to a 1 r-law (for r⩾ 50 km). 2.(2) For a given line of a given station the SES emitted from a given seismic region (r∼-const.) have ΔV-values that increase with the magnitude; to a good approximation log ΔV versus M gives a straight line with a slope between 0.3 and 0.4. If for the same station and line another seismic region is considered, the straight line is parallel to the previous one but shifted by a constant amount that depends purely on the ratio of the epicentral distances. Therefore, if the quantity log (ΔV· r) for earthquakes emitted from various seismic regions is plotted versus M, a unique linear relation for each station appears with the same slope. 3.(3) The simultaneous ΔV-values of a given EQ recorded at various stations do not follow a 1 r dependence. The value ΔV L of the electric field in each direction, divided by a suitable factor—an empirically determined effective resistivity—gives a quantity characteristic of the variation of the component of the current density in the earth which can be designated as the intensity of the signal in this direction. By combining the values of the two directions the total intensity J of the SES results. This quantity is found to attenuate with the distances of the stations according to a 1 r-law so that log (J· r) is an unique linear function of M for all stations and seismic regions.