Borehole Seismometer Azimuth Detection in Jiangsu Seismic Network
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摘要: 为获取江苏省测震台网井下地震计精确方位角,架设地面参考地震计,将其精确指北,并与井下地震计检测结果进行对比,利用相关分析法计算22个深井台站精度较高的方位角。研究结果表明,受多因素制约,井下地震计检测结果普遍偏差较大,部分台站水平向分量几乎反向,如提井,需重新进行方位角检测;地面与井下地震计同频带有利于提高相关性,从而获取高精度检测结果;利用不同频带地震计进行井下地震计方位角检测时,对较宽频带地震计进行仿真处理尤为重要;溧阳2台站新建井下地震计检测结果表明相关分析法可应用于井下地震计方位角检测;尽可能选择台基噪声功率谱密度曲线具有明显波峰频段作为滤波频段,有利于提高地面与井下地震计观测数据相关性,提高方位角检测精度。Abstract: In order to obtain the accurate azimuth angles of borehole seismometer in Jiangsu seismic network, the ground reference seismometer is set up to accurately point north accurately. Comparative observation between ground and borehole seismometer has been done . Accurate azimuths of 22 borehole seismometers were obtained, and we draw the following conclusions: The azimuth angle deviations of borehole seismometer are generally large due to the restriction of many factors, and the horizontal components of some stations are almost reversed. Remount of borehole seismometer must changes the azimuth, so the azimuth detection must be carried out again.The same frequency band between ground and borehole seismometers is beneficial to improve the correlation and obtain higher precision detection results.The comparison observation of different frequency band seismometers needs to be simulated. Azimuth detection of Liyang 2 borehole seismometer proves that the correlation analysis method is feasible to detect the azimuth of borehole seismometer. The frequency band with obvious peak on the power spectrum curve of the background noise is selected as the filtering frequency band as far as possible, which is beneficial to improve the correlation between ground and borehole seismometer observation data and improve the accuracy of azimuth detection.
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表 1 井下地震台基本信息
Table 1. The fundamental information of borehole seismic stations
台站名 代码 台基岩性 安装深度/m 安装方式 地震计型号 频带范围 数采型号 采样率/Hz 沛县 PX 石英砂 280 卡壁 JDF-2 20 s~20 Hz EDAS-24IP 100 280 卡壁 GL-S60B 60 s~50 Hz EDAS-24GN 100 淮安 HUA 松散沉积层 315 卡壁 JDF-2 20 s~50 Hz EDAS-24IP 100 315 卡壁 GL-S60B 60 s~50 Hz EDAS-24GN 100 海安 HA 松散沉积层 425 卡壁 JDF-3 120 s~50 Hz EDAS-24GN 100 425 卡壁 GL-S60B 60 s~50 Hz EDAS-24GN 100 大丰 DF 松散沉积层 409 卡壁 JDF-3 120 s~50 Hz EDAS-24GN 100 409 卡壁 GL-S60B 60 s~50 Hz EDAS-24GN 100 阳光岛 YGD 基岩 530 卡壁 JDF-3 120 s~50 Hz EDAS-24GN 100 530 卡壁 GL-S60B 60 s~50 Hz EDAS-24GN 100 泰州 TZ 沉积岩 500 落底 GL-S60B 60 s~50 Hz EDAS-24GN 100 盐城 YC 松散沉积层 410 卡壁 GL-S60B 60 s~50 Hz EDAS-24GN 100 宝应 BY 石英砂 450 卡壁 CMG-3TB 120 s~50 Hz EDAS-24GN 100 射阳 SY 松散沉积层 460 卡壁 GL-S60B 60 s~50 Hz EDAS-24GN 100 如东 RD 灰岩 450 落底 GL-S60B 60 s~50 Hz EDAS-24GN 100 启东 QD 灰岩 410 落底 GL-S60B 60 s~50 Hz EDAS-24GN 100 溧阳 LY 安山玄武岩 80 落底 GL-S60B 60 s~50 Hz EDAS-24GN 100 溧阳2 LY2 安山玄武岩 203 落底 GL-S60B 60 s~50 Hz EDAS-24GN 100 高邮 GY 松散沉积层 452 落底 GL-S60B 60 s~50 Hz EDAS-24GN 100 南通 NT 石英砂 159 卡壁 GL-S60B 60 s~50 Hz EDAS-24GN 100 兴化 XH 混合花岗岩 490 落底 GL-S60B 60 s~50 Hz EDAS-24GN 100 兴化2 XH2 混合花岗岩 510 卡壁 GL-CS60B 60 s~50 Hz EDAS-24GN 100 涟水 LAS 石英岩 400 落底 GL-S60B 60 s~50 Hz EDAS-24GN 100 丰县 FX 石英砂 405 落底 GL-S60B 60 s~50 Hz EDAS-24GN 100 李堡 LIB 松散沉积层 450 落底 GL-CS60B 60 s~50 Hz EDAS-24GN 100 坪山 PIS 泥岩 425 落底 GL-S60B 60 s~50 Hz EDAS-24GN 100 扬中 YAZ 泥岩 416 落底 GL-CS60B 60 s~50 Hz EDAS-24GN 100 表 2 地面参考地震计参数
Table 2. The parameters of ground referenceseismometer
地震计型号 地震计序列号 频带范围 电压灵敏度/ V·m−1·s−1 UD分向 EW分向 NS分向 GL-S120 G14408VS 120 s~50 Hz 1 993.76 1 986.20 1 994.00 GL-S60 G11842VS 60 s~50 Hz 2 002.26 2 000.32 2 005.64 表 3 井下地震计方位角检测结果
Table 3. The azimuth detection results of borehole seismometers
台站名 测试地震计型号 参考地震计型号 滤波频带/Hz 参考地震计方位角/° 测试地震计方位角/° 校正后井下方位角/° 相关系数 沛县 JDF-2 GL-S60 0.2~0.3 359.9 186.2 186.1 0.921 89 淮安 JDF-2 GL-S60 0.2~0.3 359.6 166.7 166.3 0.895 56 GL-S60B GL-S60 0.2~0.3 0.1 50.2 50.1 0.992 51 海安 JDF-3 GL-S120 0.2~0.3 359.9 146.2 146.1 0.814 48 GL-S60B GL-S60 0.2~0.3 359.9 314.8 314.7 0.997 47 大丰 JDF-3 GL-S120 0.2~0.3 359.8 184.1 183.9 0.831 92 GL-S60B GL-S60 0.2~0.3 0.1 122.3 122.4 0.990 79 阳光岛 JDF-3 GL-S120 0.2~0.3 0.2 162.4 162.6 0.800 07 GL-S60B GL-S60 0.2~0.3 359.6 340.6 340.2 0.960 31 泰州 GL-S60B GL-S120 0.2~0.3 0.0 −4.5 −4.5 0.928 45 盐城 GL-S60B GL-S120 0.2~0.3 0.0 −137.3 −137.3 0.900 50 宝应 CMG-3TB GL-S120 0.2~0.3 359.8 6.8 6.6 0.963 71 射阳 GL-S60B GL-S60 0.1~0.2 359.6 346.0 345.6 0.968 96 如东 GL-S60B GL-S60 0.2~0.3 0.3 329.9 330.2 0.937 37 启东 GL-S60B GL-S60 0.2~0.3 0.0 6.2 6.2 0.823 46 溧阳 GL-S60B GL-S60 0.2~0.3 0.3 −2.2 −1.9 0.917 73 溧阳2 GL-S60B GL-S60 0.2~0.3 0.0 176.5 176.5 0.997 48 高邮 GL-S60B GL-S60 0.2~0.3 359.8 299.5 299.3 0.975 95 南通 GL-S60B GL-S120 0.2~0.3 359.5 347.4 346.9 0.997 02 兴化 GL-S60B GL-S60 0.2~0.3 359.3 84.3 83.6 0.988 24 兴化2 GL-CS60B GL-S60 0.2~0.3 0.0 299.9 299.9 0.990 08 涟水 GL-S60B GL-S60 0.2~0.3 0.0 233.3 233.3 0.938 00 丰县 GL-S60B GL-S60 0.2~0.3 0.0 301.8 301.8 0.956 90 李堡 GL-CS60B GL-S60 0.2~0.3 359.6 147.5 147.1 0.998 01 坪山 GL-S60B GL-S60 0.2~0.3 0.1 86.6 86.7 0.979 15 扬中 GL-CS60B GL-S60 0.2~0.3 0.6 211.8 212.4 0.996 99 表 4 沛县、淮安台站24 h平均检测结果
Table 4. 24-hour average azimuth detection results of Peixian、Huaian
台站 状态 东西向分量 南北向分量 平均值 相对方位角/º 相关系数 相对方位角/º 相关系数 相对方位角/º 相关系数 沛县 仿真 185.3 0.882 14 187.0 0.961 63 186.1 0.921 89 未仿真 188.0 0.697 36 186.0 0.962 12 186.8 0.829 74 淮安 仿真 164.7 0.846 90 168.6 0.944 21 166.3 0.895 56 未仿真 160.1 0.729 65 169.1 0.955 54 164.6 0.842 60 -
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