高曙德, 罗维斌, 苏永刚, 梁子斌, 李旭升, 韩英, 孙海洋. 2017: 编码源地电阻率观测试验. 地震学报, 39(4): 506-519. DOI: 10.11939/jass.2017.04.006
引用本文: 高曙德, 罗维斌, 苏永刚, 梁子斌, 李旭升, 韩英, 孙海洋. 2017: 编码源地电阻率观测试验. 地震学报, 39(4): 506-519. DOI: 10.11939/jass.2017.04.006
Gao Shude, Luo Weibin, Su Yonggang, Liang Zibin, Li Xusheng, Han Ying, Sun Haiyang. 2017: Georesistivity observational experiment based on encoded source. Acta Seismologica Sinica, 39(4): 506-519. DOI: 10.11939/jass.2017.04.006
Citation: Gao Shude, Luo Weibin, Su Yonggang, Liang Zibin, Li Xusheng, Han Ying, Sun Haiyang. 2017: Georesistivity observational experiment based on encoded source. Acta Seismologica Sinica, 39(4): 506-519. DOI: 10.11939/jass.2017.04.006

编码源地电阻率观测试验

Georesistivity observational experiment based on encoded source

  • 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AB产生的电流信号作为系统输入信号,测量电极MN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: The accurate observation of earth resistivity is an effective method for earthquake prediction. In the face of increasingly severe electromagnetic interference, a method of ground resistivity observation based on coded source circular cross-correlation identification is proposed. The measured geoelectrical structure can be treated as the system to be identified, using the coded current signal excited by power supply electrodes A and B as the input signal of the system, and the voltage signal between the electrodes M and N is the system output response, and the input and output signals are synchronously sampled into the time series, then a reference signal is generated according to sampled coded current time series. Next, the circular cross-correlation operation between input signal and the reference signal, and between output signal and the reference signal were performed separately, and the cross-correlation time series were converted into the frequency domain by fast Fourier transform and the apparent resistivity spectrum (amplitude and phase) of the earth to be detected can be deduced. A short experiment using this method was carried out at two stations of Lanzhou observatory and Hanwang station, the results showed that this method has a strong ability to restrain noise, and can achieve high frequency resolution and measurement accuracy. The multi-frequency apparent resistivity spectrum provides the conditions for the removal of electromagnetic coupling. The feasible technical scheme is put forward in this project, want to develop instrument, to optimize the main experimental parameters, and get a higher precision resistivity monitoring and the phase monitoring ability. The result can provide the data support for the study of the characteristics of time, location and intensity of seismic anomaly information and its relationship with strong earthquakes, and it also has practical significance and application value in the field of earthquake prevention and disaster reduction.

     

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