基于概率功率谱密度的山西地震预警台网地噪声水平计算与分析

Calculation and analysis of ground noise level of Shanxi earthquake early warning network based on PPSD method

地震监测预警要求高质量台站波形数据记录,而测震台站设备的异常运行导致波形异常时有发生,影响了台站数据质量。面对数量骤增的预警台站,仅依靠人工浏览波形方式难以及时发现波形异常台站,无法保证观测数据质量。以山西预警台网基准站、基本站及一般站实时记录的波形数据为基础,采用概率功率谱密度(PPSD)计算方法,实现对预警台站地噪声水平的计算,同时利用PDF图对比分析部分台站正常与异常波形特点。结果表明:地震计能有效记录较宽频带内的台基噪声;加速度计能记录大于0.1 Hz的台基噪声;烈度计仅记录自噪声,无法有效记录台基噪声。分析认为,可利用该方法检验台站仪器的运行状态,以便及时发现异常台站,进而实现对台站波形数据的质量监控。

Seismic monitoring and early warning require high-quality waveform data.However,the abnormal operation of the equipment in the seismic station leads to the abnormal waveform from time to time,which affects the data quality of the station.In the face of the sudden increase in the number of stations,it is difficult to detect abnormal waveforms in time by manually waveform browsing,and the observation data quality cannot be guaranteed.Based on the real-time waveform data recorded by the base stations,basic stations,and general stations of the Shanxi earthquake early warning station network,the probabilistic power spectral density(PPSD)method is used to calculate the ground noise level of the early warning stations,and the normal and abnormal waveform characteristics of some stations are compared and analyzed by PDF diagram.The results show that the seismometer can record the ground noise in the wide band effectively.The accelerometer can record the base noise greater than 0.1 Hz.The intensity meter only records the self-noise and cannot record the ground noise effectively.The analysis shows that this method can be used to check the operating state of the station instrument to detect the abnormal station in time,and then realize the quality monitoring of the station waveform data.