地震研究

针对基于3个台站Pg震相进行震中定位时有时存在误差较大、不稳定等现象,通过分析区域速度模型差异、台站的几何分布对震中定位精度的影响,结合山东虚拟测震台网,给出了接近实际的直达Pg波视速度结构,提出了三台震中定位的综合解决方案。对2009～2013年山东虚拟测震台网内1 555次地震的震中定位结果表明,应用三台定位方法得到的震中定位误差平均为8.7 km(与台网定位结果相比),提高了震中定位的精度,减少了震中不能确定的概率。

Aiming at the phenomenon of the larger error and instability that exits in the epicenter location based on Pg onsets of three stations,combined with virtual seismic network of Shandong Province,we analyze the influence of the difference of regional velocity structure and geometric distribution of stations on locating precision of epicenter,and give the apparent velocity model of direct Pg wave to put forward the integrated solutions scheme on epicenter location based on Pg onsets of three stations. The epicenter location results of 1 555 earthquakes recorded by the virtual seismic network of Shandong Province from 2009 to 2013 indicates that the average error of epicenter location is 8.7 km by Pg onsets of three stations(compared with the epicenter location in network),which can improve the precision of epicenter location and deduce the probability of epicenter cannot be determined.

引言
1 三台震中定位方法
2 V图单元内地震直达P波视速度确定
3 台站的几何分布对震中测定结果的影响
4 三台震中定位解决方案及应用实例分析
5 讨论与结论

图1 用于直达P波视速度反演的地震震中分布图<br/>Fig.1 Distribution of earthquake epicenter to be used for apparent velocity inversion of Pg wave

图1 用于直达P波视速度反演的地震震中分布图
Fig.1 Distribution of earthquake epicenter to be used for apparent velocity inversion of Pg wave

图2 用于直达P波视速度反演的地震射线分布图(由1.5°逐0.1°滑动计算得到)<br/>Fig.2 Distribution of seismic wave rays to be used for apparent velocity inversion of Pg wave(calculation of 1.5° sliding average value and 0.1°sliding step)

图2 用于直达P波视速度反演的地震射线分布图(由1.5°逐0.1°滑动计算得到)
Fig.2 Distribution of seismic wave rays to be used for apparent velocity inversion of Pg wave(calculation of 1.5° sliding average value and 0.1°sliding step)

图3 由山东虚拟测震台网形成的V图及其每个V图单元区内的直达P波视速度分布<br/>Fig.3 Voronoi diagrams formed by the virtual seismic network of Shandong Province and the apparent velocity distribution of Pg wave in each unit of Voronoi diagran

图3 由山东虚拟测震台网形成的V图及其每个V图单元区内的直达P波视速度分布
Fig.3 Voronoi diagrams formed by the virtual seismic network of Shandong Province and the apparent velocity distribution of Pg wave in each unit of Voronoi diagran

图4 山东虚拟测震台网台站(实心三角)分布及2009至2013年期间网内地震分布(空心圆圈)<br/>Fig.4 Distribution of stations in virtual seismic network of Shandong Province(solid triangle)and epicenter distribution inside the network from 2009 to 2013(hollow circle)

图4 山东虚拟测震台网台站(实心三角)分布及2009至2013年期间网内地震分布(空心圆圈)
Fig.4 Distribution of stations in virtual seismic network of Shandong Province(solid triangle)and epicenter distribution inside the network from 2009 to 2013(hollow circle)

图5 图4中地震发生后前3个触发台站拟合优度分布情况<br/>Fig.5 The goodness of fit distribution for the first threetriggered stations after the earthquake in Fig.4

图5 图4中地震发生后前3个触发台站拟合优度分布情况
Fig.5 The goodness of fit distribution for the first threetriggered stations after the earthquake in Fig.4

图6 地震发生后山东虚拟测震台网第1个触发台站和第3个触发台站震中距统计分布情况<br/>Fig.6 The epicentral distance distribution about the first and the third triggered stations after the earthquake in the virtual seismic network of Shandong Province

图6 地震发生后山东虚拟测震台网第1个触发台站和第3个触发台站震中距统计分布情况
Fig.6 The epicentral distance distribution about the first and the third triggered stations after the earthquake in the virtual seismic network of Shandong Province

图7 根据不同速度模型和三台震中定位解决方案得到的震中定位误差及其精度分布<br/>Fig.7 Epicenter locating error and precision distribution obtained by different velocity model and epicenter location of three stations

图7 根据不同速度模型和三台震中定位解决方案得到的震中定位误差及其精度分布
Fig.7 Epicenter locating error and precision distribution obtained by different velocity model and epicenter location of three stations

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备注

引言

1 三台震中定位方法

2 V图单元内地震直达P波视速度确定

3 台站的几何分布对震中测定结果的影响

4 三台震中定位解决方案及应用实例分析

5 讨论与结论

期刊信息