【作者】 宋艳茹；

【导师】 席继楼；

【作者基本信息】 中国地震局地震预测研究所 ， 固体地球物理学， 2012， 硕士

【摘要】 地震电磁学源于地球电磁学，基于地球电磁学的理论基础和方法技术，探索与孕震过程有关的电磁现象以及地球介质的电磁性质的变化规律，为地震预报以及孕震过程的理论研究提供服务。我国在1976年唐山大地震后开始进行地震电磁扰动（又称电磁辐射、电磁波等）现象的观测研究，到目前为止，我国全国范围内建立了大约200个电磁扰动试验观测台站，主要是对0.1Hz10Hz的电磁场信号进行测量，一般采用背景变化与事件变化相结合的方式获取超低频段地震电磁场扰动变化信息，已经有着30多年的实践和应用研究，在地震监测预测中发挥了一定的作用。本文结合我国地震电磁扰动观测研究的现状与进展，开展一种新的超低频地震电磁场观测方法和观测技术研究。该研究以高采样率数据采集技术为依托，利用宽频带、高精度、高灵敏度的电磁传感器，对地球表面的0.1Hz几十Hz之内的天然电场和磁场及其随时间变化序列进行同步测量，期望获取较宽频带的电场和磁场在时间域和频率域的变化特征和有关事件信息。电场测量电极是将连接大地和金属测量线路的导电装置，用于传导地表电场强度及其随时间变化信息。我国目前地震电磁扰动测量中以使用不锈钢电极和金属铅电极为主，也有利用井下套管作为电极的测量方式。论文对一种Pb-PbCl2不极化的原理、实现方法及其主要性能进行了分析和研究，并对其在超低频电场测量应用中的可行性进行讨论。磁感应传感器又称感应式磁传感器，感应式磁传感器中的感应线圈是测量电磁场变化最方便、最简单、最古老的磁接收器，可以探测从极低频到音频段（0.0001Hz~10KHz）的微弱磁场，磁感应线圈传感器种类很多，广泛应用在大地电磁法、可控源大地电磁法、可控源电磁法、瞬变电磁法、海洋可控源电磁法等各种电磁技术中。论文着重对提高无源感应式磁传感器的灵敏度等方面做了一定的研究工作。论文对基于高采样率数据采集技术的数值分析、信号处理和信息提取方法开展了一定的研究工作。引入了极差归一化变换法对时间域的事件变化进行分析和提取；对于无源感应式磁传感器的灵敏度参数的非线性变化，利用多次曲线拟合方法，对地磁观测数据的频谱特性进行效验和修正。在十三陵地震台和怀来地震台开展了超低频段地震电磁场观测试验。2012年4月1日到5月31日期间的观测数据的分析结果发现，四个分量（电南北、电东西、磁南北、磁东西）从4月10号开始在时域和频域均出现了较大变化，该现象可能与5月28日唐山4.8级地震有关。更多还原

【Abstract】 Seismo-electromagnetics is derived from geo-electromagnetism, which explorethe electromagnetic phenomena about the process of earthquake preparation as well asthe electromagnetic(EM) change properties of the Earth medium, so as to provideservices for earthquake prediction. There has been established about200EMdisturbance observation stations in China since1976Tangshan Earthquake, mainlyusing a a combination style of background change and events change to measure theEM between0.1Hz and10Hz. Up to now there has been more than30years ofpracticing and applying research, which plays a role in Earthquake monitoring andprediction.This paper mainly carried out a new kind of research of ultra-low frequencyseismic electromagnetic (EM) field observation on the status and progress of EM inChina. Based on high sampling rate data acquisition technology as well as broad bandand high-precision electromagnetic sensors, this research could simultaneouslymeasuring the natural EMF and its time-varying sequence from Earth’s surface so asto obtain the change characters and related events of EMF in the time domain and inthe frequency domain.Electrode is a conduction device to connect the earth and metal line, which isused to conduct the earth’s surface electric field strength and its time change. In thecurrent measurement in our country, these electrodes are commonly used like stainlesssteel electrode, metal lead electrode and also cased hole electrode. This paper studieda type of Pb-PbCl2non-polarizable electrode and analyzed its technical performancefactors and principles, then discussed its feasibility in the ultra-low electric fieldmeasurement.Induction coil in magnetic induction sensor is the most convenient, the mostsimple and the oldest magnetic receiver to, which could detect the weak magneticfield from ELF to audio wave(0.001~10KHz). There are many types of magneticinduction sensors which are widely used in all EM technologies such asmagnetotelluric method, controlled source magnetotelluric method, transientelectromagnetic method, marine controlled source electromagnetic method, etc. This paper focuses on improving the sensitivity of passive inductive magnetic sensors.This paper also studied the methods of signal processing and event extractingabout high sampling rate data acquisition technology. First, introduce the pretreatmentof highly normalizing to extract event in the time domain; Then use curve fittingmethod to do spectral characteristics data validation and correction for the non-linearchanges of the sensitivity parameters of passive inductive magnetic sensors.Ultra-low frequency seismic electromagnetic field observation experiment islaunched in Huailai seismic station and Shisanling seismic station. Results of April1,2012to May31,2012show that the four components(include NS and EW componentof electric signal and magnetic signal) all had appeared great changes since April10in the time domain and frequency domain，this phenomenon may be related to theMay28,20124.8Earthquake in Tangshan.更多还原