福建地震预警台网观测数据质量评估

Evaluation of observation data quality of Fujian earthquake early warning network

针对测震、强震和烈度计三网融合所面临的数据质量评估问题,开展了区域地震预警台网背景噪声研究分析工作.利用噪声功率谱法、最大概率加速度噪声峰值(PGA)、速度噪声峰值(PGV)、位移噪声峰值(PGD)指标科学评估构成台网三类传感器的背景噪声,分析其噪声水平的差异性;采用噪声功率谱面积占比法定量评价台站噪声水平,根据不同色标展示各台站的噪声水平高低,方便直观判断站点运行状态;由实际统计,选取合适的比例,确定各类传感器噪声模型的高低基准线和正常噪声PGA、PGV、PGD的上下限,甄别出波形记录疑似异常的台站.研究结果表明:三类地震监测仪器中,地震计在全频带能完整有效地记录环境噪声,其噪声水平最低;强震仪可记录0.1 Hz以上的环境噪声,小于0.1 Hz频带主要为仪器自噪声,其噪声水平较地震计高;烈度计的记录基本是仪器的自噪声,无法记录到地球脉动,其噪声水平最高.噪声功率谱面积占比法将噪声水平划分成四个等级,能够有效评选出记录优质的台站.通过频域和时域对异常台站进行检测,极大提高检测结果的可靠性,同时也有利于对标定、异常大脉冲等误报结果的检测.台网观测数据质量评估结果,可供维护人员作为参考依据,对优质台站重点关注,对记录异常台站及时修复,保证优质台站数据的完备性,为地震预警与烈度速报产品的可靠性和准确性提供重要保障.

In response to the data quality assessment issues faced by the integration of seismometer,strong motion seismograph,and intensity meters,research and analysis work on background noise of regional early warning networks has been carried out.Using the noise power spectrum method,maximum probability acceleration noise peak(PGA),velocity noise peak(PGV),and displacement noise peak(PGD)standards,scientifically evaluate the background noise of the three types of sensors that make up the network,and analyze the differences in their noise levels;Quantitatively evaluate the noise level of stations using the noise power spectral area ratio method,and display the noise level of each station based on different color codes,making it convenient to visually judge the operation status of the station;Based on actual statistics,select appropriate proportions to determine the high and low baseline of various sensor noise models and the upper and lower limits of normal noise PGA,PGV,and PGD,and identify stations with suspected abnormal waveform records.The research results indicate that among the three types of seismic monitoring instruments,seismometers can fully and effectively record environmental noise in the full frequency band,with the lowest noise level;The strong seismic instrument can record environmental noise above 0.1 Hz,and the frequency band below 0.1 Hz is mainly due to instrument self noise,with a higher noise level than the seismometer;The recording of the intensity meter is basically the self noise of the instrument,which cannot record the Earth's pulsation and has the highest noise level.The noise power spectral area ratio method divides the noise level into four levels,which can effectively select stations with high-quality records.Detecting abnormal stations through frequency and time domains greatly improves the reliability of detection results,while also facilitating the detection of false alarms such as calibration and abnormal large pulses.The quality evaluation results of the observation data of the network can be used as a reference for maintenance personnel to focus on high-quality stations,ensure the Completeness of the data of high-quality stations,and record abnormal stations that should be repaired in a timely manner,providing an important guarantee for the reliability and accuracy of earthquake early warning and intensity quick report products.