宋晓东3,4,,,
郑斯华5,
陈惠芳6
1. 江苏省地震局, 南京 210014
2. 南京大学地球科学与工程学院, 南京 210046
3. Department of Geology, University of Illinois, Urbana, IL 61801
4. 武汉大学测绘学院, 武汉 430079
5. 中国地震局地震预测研究所, 北京 100036
6. 福建省地震局, 福州 350003
基金项目: 地震科研公益性行业专项（201508020）和国家自然科学基金（41774056，41274056）资助
详细信息
作者简介: 李细兵, 男, 1982年生, 主要从事地球物理方面研究.E-mail:lixib_2005@sina.com
通讯作者: 宋晓东, 教授, 主要从事地震学、地球内部结构等研究.E-mail:xiao.d.song@gmail.com
中图分类号: P315收稿日期:2018-10-24
修回日期:2019-04-10
上线日期:2019-05-05
A 1D P-wave velocity model of Fujian Province, China and earthquake locations from controlled explosions
LI XiBing1,2,,SONG XiaoDong3,4,,,
ZHENG SiHua5,
CHEN HuiFang6
1. Earthquake Administration of Jiangsu Province, Nanjing 210014, China
2. School of Earth Sciences and Engineering, Nanjing University, Nanjing 210046, China
3. Department of Geology, University of Illinois, Urbana, IL 61801, USA
4. School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China
5. Institute of Earthquake Science, China Earthquake Administration, Beijing 100036, China
6. Earthquake Administration of Fujian Province, Fuzhou 350003, China
More Information
Corresponding author: SONG XiaoDong,E-mail:xiao.d.song@gmail.com
MSC: P315--> Received Date: 24 October 2018
Revised Date: 10 April 2019
Available Online: 05 May 2019
摘要
摘要:通过人工爆破资料研究地球结构的独特优点是震源时间和位置精确知道.2010-2012年间福建省进行了一系列的爆破实验.本文利用手工拾取来自省地震台网记录的爆破地震初至Pg、Pn以及续至Pg波到时数据，采用联合反演方法构建了新的一维P波速度模型，即福建爆破模型（FJEM）.与华南模型相比，FJEM模型对走时的拟合程度提高了45%，有明显改善.利用不同爆破地震数据组合得到稳定类似的福建地区一维速度模型，显示福建地区存在较简单的一维速度结构.对爆破地震的重定位显示传统使用的华南模型在福建地区具有较小的水平定位误差（平均0.52±0.45 km），但存在较大深度误差（平均4.7±1.2 km）.FJEM模型表现出与华南模型相似的水平定位能力，但是震源深度误差更小（1.3±1.1 km）.对基于FJEM模型的合成天然地震目录的重定位，华南模型显示出相似的定位结果：（1）台站方位覆盖较好的福建中部地区的水平定位误差小；（2）台站方位覆盖差的福建海岸及海峡区域水平定位误差大；（3）震源深度误差则跟台站数目及方位分布没有明显的关系，而是与发震时间误差有互易关系.从中可以看出，地震水平定位误差基本上受台站方位覆盖影响，而受参考速度模型影响不大；而在深度方面，本文改进的FJEM模型不仅更加接近真实的速度结构（拟合走时更好）而且也减小了深度误差.因此建议在福建及其邻近区域的日常定位中用FJEM模型替代华南模型.
关键词: 爆破地震/
联合反演/
福建一维速度/
定位误差
Abstract:Data from controlled explosions provide a unique advantage to study velocity models as the source locations are precisely known. A series of explosion were conducted in Fujian Province in 2010-2012. In this study, we hand-picked first Pg and Pn arrivals and secondary Pg arrivals from the explosion seismograms recorded at provincial stations. Using a joint inversion method, we inverted for a new 1-D P-wave velocity model, Fujian explosion model (FJEM). The FJEM model shows a 45% improvement in fitting the travel-time data over the current routine model. Similar velocity models inverted from subsets of explosion data suggest a relative stable and simple velocity structure in Fujian province. Relocations of the explosions suggest that the traditional South China model has small horizontal location errors (average 0.52±0.45 km), but errors in depth are significant (average 4.7±1.2 km), while the FJEM model has similar horizontal location capability but much smaller errors in depth (average 1.3±1.1 km). Synthetic tests using real earthquake bulletins show similar results for the South China model:(1) for earthquakes in the interior of Fujian with good azimuthal coverage, the horizontal mislocation is small; (2) the horizontal mislocations for earthquakes along the coast and in Taiwan Strait with poor azimuthal coverage can be very large; and (3) mislocations in depth can be large regardless station distribution, which have strong trade-off with origin time errors. Essentially, the horizontal location is largely affected by station azimuthal coverage and much less by the reference model. But the improved FJEM model not only is closer to the real Earth (fit data better) but also can reduce depth mislocation. We propose that South China model be replaced and the FJEM model be used in routine earthquake locations in Fujian and perhaps neighboring regions as well.
Key words:Explosion/
Joint inversion/
Fujian 1-D velocity model/
Location error
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