华南地震

为研究地下介质电阻率随时间的变化,对水平分层均匀电阻率结构,研究了MT/CSELF视电阻率影响系数和各层对视电阻率变化的贡献,研究显示：各层电阻率的变化对MT/CSELF视电阻率的变化都有不同程度的贡献,贡献的大小与影响系数成正比,而各层影响系数都随电磁场源的周期变化;对于易受干扰的近地表层,其影响系数及对MT/CSELF视电阻率变化的贡献随周期的增加快速下降,在特定的短周期段只有近地表层对观测到的视电阻率变化有贡献而之下各层无贡献;近地表层之下各层的影响系数及对视电阻率变化的贡献则是随周期起伏变化;通过影响系数和各地层贡献分析,选择在合适的长周期段观测,可以使近地表层对视电阻率变化的贡献忽略不计,视电阻率变化主要反应深部各层的电阻率变化。研究结果对MT/CSELF观测频段的选择具有指导意义。

In order to study the change of resistivity of underground medium with time,for the horizontal layered uniform resistivity structure,the influence coefficients of apparent resistivity of MT/CSELF and the contribution of each layer to the change of apparent resistivity are studied. The research shows that: the change of the resistivity of each layer contributes to the change of the apparent resistivity of MT/CSELF in different degrees,the contribution is proportional to its influence coefficient,and the influence coefficient of each layer varies with the period of the electromagnetic field source;for near-surface layer which is susceptible to interference,its influence coefficient and contribution to the variation of apparent resistivity decrease rapidly with the increase of period,and in a certain short period range,only the near-earth surface contributes to the apparent resistivity,while the lower layers do not. The influence coefficients and the contributions to the change of the apparent resistivity of layers under the near-earth surface are fluctuated with the period. The contribution of near-surface layer to the apparent resistivity change can be neglected and the apparent resistivity change mainly reflects the resistivity changes of deep layers by choosing an appropriate long period range for observation through analysis of influence coefficients and contributions of each layer. The results of this study are instructive to the selection of observation frequency band of MT/CSELF.

引言
1 影响系数及各地层贡献的计算方法简介
2 不同频率下影响系数与各地层贡献分析
3 结论

图1 腾冲石坪测点各地层影响系数—周期曲线<br/>Fig.1 Curves of the influence coefficients of each layer with the period at Shiping site in Tengchong

图1 腾冲石坪测点各地层影响系数—周期曲线
Fig.1 Curves of the influence coefficients of each layer with the period at Shiping site in Tengchong

表1 腾冲石坪观测点几个周期点上各层影响系数及其总和<br/>Table 1 The influence coefficients of each layer and their sum at several periodic points at Shiping observation point in Tengchong

表1 腾冲石坪观测点几个周期点上各层影响系数及其总和
Table 1 The influence coefficients of each layer and their sum at several periodic points at Shiping observation point in Tengchong

表2 近地表干扰与深部变化同时存在时几个周期点上各层的贡献及视电阻率的变化率<br/>Table 2 Contributions of each layer and the change rate of apparent resistivity at several periodic points when near-surface interference and deep changes exist simultaneously

表2 近地表干扰与深部变化同时存在时几个周期点上各层的贡献及视电阻率的变化率
Table 2 Contributions of each layer and the change rate of apparent resistivity at several periodic points when near-surface interference and deep changes exist simultaneously

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备注

引言

1 影响系数及各地层贡献的计算方法简介

2 不同频率下影响系数与各地层贡献分析

3 结论

期刊信息