辽宁地区Pb震相识别及康拉德界面研究

doi:10.12196/j.issn.1000-3274.2021.03.006

地震 ›› 2021, Vol. 41 ›› Issue (3): 77-89.doi: 10.12196/j.issn.1000-3274.2021.03.006

辽宁地区Pb震相识别及康拉德界面研究

安祥宇, 赵倩, 李恩来, 李子昊, 康晓珊

辽宁省地震局, 辽宁沈阳 110031

收稿日期:2020-09-17 修回日期:2020-11-20 出版日期:2021-07-31 发布日期:2021-11-02
作者简介:安祥宇(1986-), 男, 辽宁沈阳人, 工程师, 主要从事地震监测及数字地震资料分析工作。
基金资助:
中国地震局监测、预报、科研三结合课题(3JH-202001022); 中国地震局地震预测研究所基本科研业务专项(2018IEF010202)

Identification of Pb Seismic Phase and Inversion of Conrad Interface in Liaoning Area

AN Xiang-yu, ZHAO Qian, LI En-lai, LI Zi-hao, KANG Xiao-shan

Earthquake Administration of Liaoning Province, Shenyang 110031, China

Received:2020-09-17 Revised:2020-11-20 Online:2021-07-31 Published:2021-11-02

摘要/Abstract

摘要： 本研究采用2012—2019年辽宁地震台网记录的M_L≥2.5地震波形资料, 利用理论走时与实际波形特征相结合的方法, 从114条地震记录中拾取到269条Pb震相进行分析, 结果表明辽宁地区易识别的Pb震相的周期小于Pn, 振幅介于Pn和Pg之间, 波形呈尖锐的锯齿状。使用修正后的辽宁地区速度模型计算P波理论走时发现, 当震源深度大于11 km, 震中距在80~120 km时, Pb作为初至震相到达; 震源深度小于11 km时, 辽宁地区Pb只作为续至震相到达。 Pb的频带比Pn宽, 高频能量比Pn强, 频带宽度和高频能量与Pg比较接近。 Pb的拟合速度为6.9082 km/s, 反演获得康拉德界面平均深度为23 km。通过射线路径勾勒出康拉德界面分布, 证明康拉德界面在辽宁地区及渤海湾北部横向连续。

关键词: Pb震相, 康拉德界面, 走时方程, 理论走时, 时频分析

Abstract: We collected 269 Pb seismic phases from 114 earthquakes recorded by Liaoning seismic network from 2012 to 2019. The results show that: The period of Pb is less than that of Pn and the amplitude is between the ones of Pn and Pg, and Pb seismic phase shows jagged shape and much burr. Using the modified velocity model of the Liaoning area to calculate the theoretical travel time of P-wave, we found that: when the focal depth is deeper than 11 km and the range of the epicenter distance is between 80 and 120 km, the Pb can be found as first phase. When the focal depth is less than 11 km, the Pb gradually arrives as the subsequent seismic phase. The band of Pb is wider than the one of Pn, and higher frequence energy is stronger than the one of Pn. The bandwidth and higher frequence energy of Pb and Pg are similar to Pg. The velocity of Pb is 6.9082 km/s by polynomial fitting, the average depth of Conrad interface is 23 km by using the travel-time equation inversion. The distribution of Pb ray path proves that the Conrad interface is continuously distributed in the northern part of Bohai Bay and Liaoning province area.

Key words: Pb seismic phase, Conrad interface, Travel time equation, Theoretical travel time, Time-frequency analysis

中图分类号:

P315.7

安祥宇, 赵倩, 李恩来, 李子昊, 康晓珊. 辽宁地区Pb震相识别及康拉德界面研究[J]. 地震, 2021, 41(3): 77-89.

AN Xiang-yu, ZHAO Qian, LI En-lai, LI Zi-hao, KANG Xiao-shan. Identification of Pb Seismic Phase and Inversion of Conrad Interface in Liaoning Area[J]. EARTHQUAKE, 2021, 41(3): 77-89.

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辽宁地区Pb震相识别及康拉德界面研究

Identification of Pb Seismic Phase and Inversion of Conrad Interface in Liaoning Area

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