陆良大萨卜龙宽频带地震观测台站仪器勘选

Instrument survey for broadband seismic observation station in Dasabulong,Luliang County

宽频带地震观测台站仪器勘选工作包括野外仪器测试、台基背景噪声水平计算及分析、台站综合评价。通过陆良大萨卜龙宽频带地震观测台站仪器勘选,对测试设备系统组成及辅助工具进行总结,形成用于减小气温、气流对地震计干扰的四级防护架设方法,梳理了测试数据中对于天然地震事件、干扰事件(非天然地震事件)的预处理方法。对测试数据进行干扰评估,干扰频度N=0.03<0.5,且非天然地震事件持续时间占记录时间的百分比R=0.01%<0.5%,表明勘选台址几乎不受干扰;对预处理数据进行噪声计算与分析,结果发现,在1—20 Hz频带,台基噪声三分量平均功率谱密度与全球低噪声模型NLNM相比,平均偏高17—38 dB,RM_(S)有效值小于3.16×10~(-8)m/s,表明勘选台站周边无明显干扰源,台基背景噪声水平达Ⅰ类台站建设标准。综合评价认为,该勘选点位观测环境较好,可作为宽频带地震观测台站建设站点。

The instrument survey for broadband seismic observation station includes field instrument testing,calculation and analysis of seismic background noise,and comprehensive evaluation of station.Through the instrument survey for broadband seismic observation station in Dasabulong,Luliang County,the composition of the test equipment system and auxiliary tools are summarized.A four-level protective erection method is developed to reduce the interference of temperature and airflow on the seismometer.Additionally,the preprocessing methods for natural seismic events and interference events(non-natural seismic events)in the test data are sorted out.The interference assessment of test data indicates that the interference frequency N is 0.03,which is less than 0.5,and the percentage of non-natural seismic event duration in recorded time R is 0.01%,also less than 0.5%,indicating that the surveyed site is almost undisturbed.The noise calculation and analysis of the preprocessing data revealed that the average power spectral density of the three components of the seismic noise is 17-38 dB higher than that of the global low-noise NLNM model in the 1-20 Hz band,and the RMS effective value is less than 3.16×10-8 m/s,indicating that there is no obvious source of interference in the vicinity of the surveyed site,and the background noise level of the stations meets the construction standard for Class I stations.The comprehensive evaluation concluded that the surveyed site has a good observation environment and can be used as a site for the construction of broadband seismic observation station.