地震预警仪观测地脉动差异与评估场地条件的可行性研究  

Differences of Microtretors Observed by Earthquake Early Warning Instruments and Feasibility for Evaluating Site Conditions

作　　者：师黎静[1] 崔迪宇 刘佳轩 高凯 Shi Lijing;Cui Diyu;Liu Jiaxuan;Gao Kai(Key Laboratory of Earthquake Engineering and Engineering Vibration,Institute of Engineering Mechanics,China Earthquake Administration,Harbin 150080,China)

机构地区：[1]中国地震局工程力学研究所地震工程与工程振动重点实验室,哈尔滨150080

出　　处：《震灾防御技术》2022年第3期502-515,共14页Technology for Earthquake Disaster Prevention

基　　金：国家自然科学基金(51978635);国家重点研发计划(2018 YFC1504601、2018 YFC1504004)。

摘　　要：根据台站场地条件进行地震动参数校正,有助于提高地震预警的有效性和准确性。针对我国地震预警台网中部分台址场地条件信息不完整及观测仪器的多样性,通过采用不同灵敏度的力平衡式加速度仪、速度仪和MEMS烈度仪,同时进行大量不同类别场地的地脉动观测,多角度对比分析时、频差别,探讨基于地震预警仪观测地脉动评价场地条件的可行性。结果表明,加速度仪灵敏度越高,H/V谱比卓越频率越易识别;速度仪与力平衡式加速度仪观测的地脉动,三分向傅氏谱和H/V谱比的谱形与卓越频率均一致;与TAG-33M强震仪相比,TMA-53烈度仪观测的地脉动整体幅值略高,波形较差,但随着振幅增大趋于一致;在近80%的场地上,TAG-33M强震仪与TMA-53烈度仪观测的地脉动傅氏谱卓越频率相差<0.5 Hz;当幅值均方根值>0.05 Gal时,TAG-33M强震仪与TMA-53烈度仪观测的地脉动竖向和水平向傅氏谱均趋于一致;当幅值均方根值为0.02 Gal~0.05 Gal时,TAG-33M强震仪与TMA-53烈度仪观测的地脉动竖向和水平向傅氏谱谱形均有较高的相似性;当幅值均方根值<0.02 Gal时,TAG-33M强震仪与TMA-53烈度仪观测的地脉动傅氏谱谱形相差较大,相似性低;依据TAG-33M强震仪观测地脉动H/V谱比的卓越频率判定场地类别,准确率达83.3%;TMA-53烈度仪观测地脉动的H/V谱比过于平坦,大多数场地上卓越频率识别困难。The accuracy of earthquake early warning can be improved by calibration according to site conditions. The site conditions of many observation stations are unknown and different kinds of observation instruments are deployed in the stations of national earthquake early warning network. The microtremors are observed continuously for a long time at the same site by the different instruments,including force-balanced accelerometers, MEMS accelerometers, and velocimeters with different sensitivities. Then the time and frequency differences were compared and analyzed and the feasibility of evaluating the site conditions was discussed. The results show that the higher the sensitivity of the accelerometer, the easier it is to identify the predominant frequency of H/V spectrum;The Fourier spectra of three components and the H/V spectra of the microtremor observed by velocimeters and force-balance accelerometers are approximately the same;Compared with TAG-33M(Force-balance Accelerometer), the amplitudes of microtremors observed by TMA-53(MEMS Accelerometer) are slightly higher and the qualities of waveforms are poor, but they tends to be consistent with the increase of amplitude;The predominant frequency differences of Fourier spectra are less than 0.5 Hz at nearly 80% sites;When the amplitude root mean square(RMS) is greater than 0.05 Gal, the vertical and horizontal Fourier spectra of the two tend to be consistent;When RMS is in the range of 0.02 Gal~0.05 Gal, the vertical and horizontal Fourier spectra of the two have high similarity;When RMS is less than 0.02 gal, the Fourier spectra of the two are quite different and have low similarities;According to the predominant frequency of H/V spectra observed by TAG-33M, the accuracy of site classification is 83.3%;The H/V spectra of the microtremor observed by TMA-53 are too flat to identify predominant frequency on most sites.

关 键 词：地脉动 场地条件 地震预警 力平衡式加速度仪 MEMS烈度仪 

分 类 号：P315.62[天文地球—地震学]