﻿ 影响山西台网地震定位因素的定量分析
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 大地测量与地球动力学  2024, Vol. 44 Issue (5): 534-538  DOI: 10.14075/j.jgg.2023.07.129

### 引用本文

YIN Weiwei, ZHENG Yadi, ZHANG Hui. Quantitative Analysis of Factors Affecting SeismicLocation of Shanxi Network[J]. Journal of Geodesy and Geodynamics, 2024, 44(5): 534-538.

### Foundation support

Project of Shanxi Earthquake Agency, No. SBK-2328, SBK-2424; Youth Fund of Science and Technology Department of Shanxi Province, No. 201801D221044; The Spark Program of Earthquake Technology of CEA, No. XH23008YA; Project of National Continental Rift Valley Dynamics Observatory of Taiyuan, No. NORSTY20-13.

### Corresponding author

ZHANG Hui, senior engineer, majors in seismic phase and source mechanism, E-mail: 511934064@qq.com.

### 第一作者简介

YIN Weiwei, senior engineer, majors in natural seismic tomography and source mechanism, E-mail: wwyin_sx@163.com.

### 文章历史

1. 山西省地震局，太原市晋祠路二段69号，030021;
2. 太原大陆裂谷动力学国家野外科学观测研究站，太原市晋祠镇，030025

1 研究方法

 图 1 山西地区台站和假设震中位置分布 Fig. 1 Location distribution of stations and assumed epicenter in Shanxi region

2 影响因素定量分析 2.1 计算理论走时

 $\frac{t^2}{t_0^2}-\frac{\varDelta^2}{h^2}=1$ (1)

 $t=\frac{\varDelta}{v_3}+(2 H-h) \frac{\cos i_0}{v_1}$ (2)

 $t=\frac{H_1}{\nu_1 \operatorname{sine}_2}+\frac{h-H_1}{\nu_2 \operatorname{sine}_2}$ (3)
 $\begin{gathered} \varDelta=H_1 \cot e_1+\left(h-H_1\right) \cot e_2 \end{gathered}$ (4)

 $\begin{gathered} t=\frac{\varDelta}{v_3}+(2 H-h) \sqrt{\frac{1}{v_1^2}-\frac{1}{v_3^2}}+ \\ 2 H_2 \sqrt{\frac{1}{v_2^2}-\frac{1}{v_3^2}} \end{gathered}$ (5)

2.2 地壳速度模型对震源位置的影响

 图 2 地壳速度模型参数 Fig. 2 Parameters of crustal velocity model

 图 3 震中位置差与地壳速度模型变化的关系 Fig. 3 Relation between epicenter position difference and crustal velocity model change

 图 4 震源深度偏差与地壳速度模型变化的关系 Fig. 4 Relation between focal depth deviation and crustal velocity model change
2.3 台网布局对震源位置的影响

 图 5 最大空隙角和震源位置差变化的关系 Fig. 5 Relationship between maximum void angle and source position difference
2.4 震相拾取精度对震源位置的影响

 图 6 P波拾取误差和震源位置差变化的关系 Fig. 6 Relation between P wave picking errorand source position difference
3 结语

1) 地壳速度模型、台网布局及震相拾取精度均可对震源位置的准确测定造成不同程度的影响，尤其对震源深度的影响更明显。

2) 当最大空隙角小于30°且震相拾取精度较高时，由地壳速度模型差异导致的山西台网地震定位震中位置差不超过5 km，但震源深度偏差可能大于20 km；上地壳P波速度(v1)对震中位置的影响最大，而震源深度受莫霍面深度的影响显著。

3) 震相拾取精度直接影响着震中位置的测定，当速度模型选取恰当、台站分布均匀、最大空隙角小于30°时，为使震中位置符合Ⅰ类精度(5 km)要求，P波拾取误差不得超过4 s。

4) 在条件允许的情况下，为保证地震定位有较高的精度，应尽可能减小最大空隙角，使其保持在180°以内。

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Quantitative Analysis of Factors Affecting SeismicLocation of Shanxi Network
YIN Weiwei1,2     ZHENG Yadi1,2     ZHANG Hui1,2
1. Shanxi Earthquake Agency, 69 Second Section of Jinci Road, Taiyuan 030021, China;
2. National Continental Rift Valley Dynamics Observatory of Taiyuan, Jinci Town, Taiyuan 030025, China
Abstract: Using numerical simulation based on the existing station layout of Shanxi Network, we quantitatively analyze the effects of crustal velocity model, network layout and seismic phase picking accuracy on seismic source location. The results show that the three factors have different effects on the accurate location of seismic source. In the crustal velocity model, the upper crust velocity has the greatest influence on the epicenter location, and the epicenter location is more sensitive to the change of Moho velocity. The deviation of epicentral position caused by a single change of crustal velocity model is usually less than 5 km, the focal depth is very sensitive to the change of crustal velocity model, especially the Moho depth, and the maximum deviation may exceed 20 km. Without considering other factors, the maximum deviation between the epicenter position and the focal depth measured within 4 s with P-wave picking accuracy is not more than 2 km and 5 km. When the crustal velocity model is suitable and the seismic phase picking accuracy is high, the station layout with the maximum void Angle of 0°-180° has a better constraint on the focal location, the epicenter deviation is basically less than 1 km, and the focal depth deviation is slightly larger, about 2 km.
Key words: Shanxi region; crustal velocity model; seismic phase picking accuracy; network layout