编码源地电阻率观测试验

发布时间：2019-06-20 04:15

【摘要】：地电阻率的高精度观测是实现地震预测预报的前提之一.面对日益严重的电磁干扰,提出了基于编码源循环互相关辨识技术的地电阻率观测方法,其实质是将待测地质体视为待辨识系统,利用编码源信号激励供电电极A和B产生的电流信号作为系统输入信号,测量电极M与N之间的电压信号作为系统响应输出,将输入和输出信号严格同步采样为时间序列,分别与参考信号进行循环互相关运算并转换至频率域计算获得待探测地电阻率谱(幅度和相位).由于系统环境的干扰和随机噪声与编码源信号不相关,通过循环互相关运算可以达到抑制环境随机噪声和干扰的目的.这种地电阻率观测体系在环境干扰较大的甘肃省兰州观象台和陇南汉王地震台站利用现有的观测场地和线路进行了观测试验,测量结果显示,数据的一致性好、均方差小,说明该方法在强干扰环境下具有较好的抗电磁干扰能力,观测频带较以往直流电法测量有较大的扩展.该方法为现有地面地电阻率台站持续发展提供了技术保障,可为地震预报与科学研究提供高质量的地电阻率观测数据.
[Abstract]:High precision observation of earth resistance is one of the prerequisites for earthquake prediction and prediction. In the face of increasingly serious electromagnetic interference, a ground resistance observation method based on cyclic cross-correlation identification technology of coding source is proposed. In essence, the geological body to be tested is regarded as the system to be identified, the current signal generated by the power supply electrode A and B excited by the coding source signal is used as the input signal of the system, the voltage signal between the measuring electrode M and N is used as the system response output, and the input and output signals are strictly synchronously sampled into the time series. The cyclic cross-correlation operation with the reference signal is carried out and converted to the frequency domain to obtain the resistivity spectrum (amplitude and phase) of the ground to be detected. Because the interference and random noise in the system environment are not related to the coded source signal, the purpose of suppressing the random noise and interference in the environment can be achieved by cyclic cross-correlation operation. The observation experiments are carried out by using the existing observation sites and circuits at Lanzhou observation Station and Hanwang Seismic Station in Gansu Province, where the environmental interference is large. The measurement results show that the data are consistent and the mean variance is small, which indicates that the method has better anti-electromagnetic interference ability in strong interference environment, and the observation frequency band is greatly expanded compared with the previous DC method. This method provides a technical guarantee for the sustainable development of the existing ground resistance stations and can provide high quality ground resistance observation data for earthquake prediction and scientific research.
【作者单位】：中国地震局兰州地震研究所;甘肃省有色地质调查院;
【基金】：中国地震局地震科技星火计划(XH18047) 国家自然科学基金(41174059) 甘肃省地震局科技发展基金(2016Y01)联合资助
【分类号】：P315.73

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