地震研究

基于单台P波初始记录的地震震中和震级快速测定方法研究^*

(山东省地震局,山东济南 250014)

Quick Measuring Method Study for Earthquake Epicenter and Magnitude Based on Initial Recording of the P Wave Recorded at the Single Station

LIU Xi-qiang,LI Xia,CAI Yin,ZHAO Rui,LI Hong,ZHOU Yan-wen,

(Earthquake Administration of Shandong Province,Jinan 250014,Shandong,China)

Keywords：Shandong Seismic Network; single station location; azimuth determining; earthquake warning

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利用山东数字化测震单台三分向记录,选择2种测定地震方位角方法和7种数据预处理方法,通过对实际结果的系统对比分析,确定了最佳的测定地震方位角的技术方案和适于地震预警的测震台站。对测定震中距和震级的方法进行了改进,得到了最佳的根据直达P波前2 s波形的包络特征参数求震中距、峰值速度的统计关系,以及根据包络特征参数求震级的标度关系。快速测定震中距和震级方法在实时地震预警中具有应用前景。

Based on initial motions of the three-component P wave data recorded at a single station in Shandong Seismic Network,compared with actual results,we established the optimum technical scheme of measuring earthquake azimuth and the stations applying to earthquake early warning from two kinds of measuring earthquake azimuth methods and seven kinds of data preprocessing methods. We improved the method of determining earthquake magnitude and epicenter distance,and got the best statistical relation between epicenter distance and peak velocity using envelop characteristic parameters of 2s waveforms before the P arrivals. We also got magnitude scaling relation based on the envelope characteristic parameter. The quick measuring method for earthquake epicenter and magnitude exhibits practical application prospect in real-time earthquake early warning.

引言
1 基于单台直达P波定位方法
2 资料与结果分析
3 讨论与结论

图1 根据椭圆型滤波器对合成模拟仿真信号的带通滤波结果(a)椭圆型带通滤波器的幅频特性;(b)由15 Hz、6.0 Hz余弦波合成的仿真信号;(c)带通滤波信号与指定频段仿真信号的对比<br/>Fig.1 Band-pass filtering result of composite simulation signal based on elliptic filter (a)amplitude frequency characteristic of elliptic band-pass filter;(b)simulation signal composited by cosine waves with 15 Hz and 6.0 Hz;(c)comparison between band-pass filtering signal and simulation signal with specified frequency band

图1 根据椭圆型滤波器对合成模拟仿真信号的带通滤波结果(a)椭圆型带通滤波器的幅频特性;(b)由15 Hz、6.0 Hz余弦波合成的仿真信号;(c)带通滤波信号与指定频段仿真信号的对比
Fig.1 Band-pass filtering result of composite simulation signal based on elliptic filter (a)amplitude frequency characteristic of elliptic band-pass filter;(b)simulation signal composited by cosine waves with 15 Hz and 6.0 Hz;(c)comparison between band-pass filtering signal and simulation signal with specified frequency band

图2 乳山台垂向记录(a)及其应用椭圆型带通滤波方法得到的处理结果(b)<br/>Fig.2 Vertical component recording recorded by Rushan Station(a)and its filtered result by the elliptic band-pass filter(b)

图2 乳山台垂向记录(a)及其应用椭圆型带通滤波方法得到的处理结果(b)
Fig.2 Vertical component recording recorded by Rushan Station(a)and its filtered result by the elliptic band-pass filter(b)

表1 分析数据的预处理及测定方位角的方法说明<br/>Tab.1 The method statement for pretreatment of analytical data and determination of azimuths

表1 分析数据的预处理及测定方位角的方法说明
Tab.1 The method statement for pretreatment of analytical data and determination of azimuths

图3 台站和地震震中分布图<br/>Fig.3 Distribution of stations and earthquake epicenters

图3 台站和地震震中分布图
Fig.3 Distribution of stations and earthquake epicenters

表2 观测台站信息及记录地震事件频次<br/>Tab.2 Information of observation stations and their earthquake recording numbers

表2 观测台站信息及记录地震事件频次
Tab.2 Information of observation stations and their earthquake recording numbers

表3 不同数据预处理和方位角测定方法的分析结果对比<br/>Tab.3 Comparative analysis of different methods on pretreatment of data and determination of azimuths

表3 不同数据预处理和方位角测定方法的分析结果对比
Tab.3 Comparative analysis of different methods on pretreatment of data and determination of azimuths

图4 震中距随斜率因子的变化及拟合直线<br/>Fig.4 Epicenter distance varying with slope factor and their fitting line

图4 震中距随斜率因子的变化及拟合直线
Fig.4 Epicenter distance varying with slope factor and their fitting line

表4 由不同参数拟合得到的震中距判别表达式及其回溯性检验结果<br/>Tab.4 The epicenter fitting formula by different parameters and their backtracking test results

表4 由不同参数拟合得到的震中距判别表达式及其回溯性检验结果
Tab.4 The epicenter fitting formula by different parameters and their backtracking test results

图5 不同震中距段分布对比(a)和不同震中距残差(单台测定震中距与实际震中距之差)段分布对比(b)<br/>Fig.5 The histogram distribution comparison of different epicenter distance segments(a)and their residuals(b)(the difference between the epicenter distance determined by signal

图5 不同震中距段分布对比(a)和不同震中距残差(单台测定震中距与实际震中距之差)段分布对比(b)
Fig.5 The histogram distribution comparison of different epicenter distance segments(a)and their residuals(b)(the difference between the epicenter distance determined by signal

图6 由台网测定的不同震级段分布对比(a)和不同震级残差(单台测定震级与台网测定之差)段分布对比(b)<br/>Fig.6 The histogram distributions comparison of different earthquake magnitude segments(a)and their residuals(b)(the difference between the earthquake magnitude determined by signal station and actual earthquake magnitude)

图6 由台网测定的不同震级段分布对比(a)和不同震级残差(单台测定震级与台网测定之差)段分布对比(b)
Fig.6 The histogram distributions comparison of different earthquake magnitude segments(a)and their residuals(b)(the difference between the earthquake magnitude determined by signal station and actual earthquake magnitude)

图7 根据单台垂向P波前2 s峰值速度和波形包络斜率因子确定的MPv与台网实际观测的ML之间的比较<br/>Fig.7 The comparison between MPv determined by peak velocity of 2 s before vertical P wave recoded by signal station'and slope factor of waveform envelope' and ML determined by actual observation in the network

图7 根据单台垂向P波前2 s峰值速度和波形包络斜率因子确定的MPv与台网实际观测的ML之间的比较
Fig.7 The comparison between MPv determined by peak velocity of 2 s before vertical P wave recoded by signal station'and slope factor of waveform envelope' and ML determined by actual observation in the network