摘要
基于2019—2022年中国地震台网198个固定台站记录的2 538次地震(M_(L)≥1.0)事件P波走时数据,采用双差层析成像方法,反演该区域三维地壳速度结构,利用双差定位和波形互相关对地震进行联合重定位,提高地震定位的精度和可靠性,揭示克拉通破坏背景下地壳结构非均匀性与地震活动的耦合关系。结果表明,重定位后地震走时残差均方根均值由1.09 s降至0.52 s,残差均值由-0.33 s优化至0.02 s,速度模型的准确性得到提高。设置4条剖线分布在地震事件较为集中的山西晋中断裂带、燕山构造带、唐山断裂带及邢台-邯郸断裂带等断裂带附近,速度结构显示,多数地震位于高速与低速异常区过渡带,地壳厚度呈横向不均匀特征,山西大同火山断陷盆地热-化学物质向上侵蚀较多,符合低速异常的特征;燕山构造带低速与高速相互交替,应力不稳定,地壳结构各向异常;在高低速异常过渡区,唐山断裂带多次发生较大地震;邢台-邯郸断裂带高速异常区可能发生过拆沉作用,导致该区域地震事件较多。岩石圈拆沉作用、热化学侵蚀作用与太平洋板块俯冲诱导的地幔对流侵蚀共同主导华北克拉通破坏的动力学机制,为理解克拉通稳定性演化与强震孕育机理提供了新的地球物理约束。
Based on the P-wave travel-time data of 2538 earthquake events(M_(L)≥1.0)recorded by 198 fixed stations of CENC from 2019 to 2023,the three-dimensional velocity structure of the crust in this area is inversed by double-difference tomography,earthquake relocation via double-difference tomography and waveform cross-correlation for enhanced accuracy and reliability,it reveals the coupling relationship between crustal structural heterogeneity and seismic activity under the background of craton destruction.The results show that after relocation,the root-mean-square(RMS)of seismic travel time residuals is reduced from 1.09 s to 0.52 s,and the residual average is optimized from-0.33 s to 0.02 s,the accuracy of the velocity model has been improved.Set four profile lines distributed in the Shanxi Jinzhong fault zone,Yanshan structural zone,Tangshan fault zone,Xingtai-Handan fault zone and other fault zones where earthquake events are more concentrated. Velocity structure analysis reveals that most seismic events are clustered within transitional zones between high- and low-velocity anomalies, the crustal thickness exhibits significant lateral heterogeneity. In the volcanic rift basin of Datong, Shanxi province, enhanced thermal-chemical upwelling corresponds to prominent low-velocity anomalies. The Yanshan tectonic zone displays alternating low-velocity and high-velocity anomalies, reflecting unstable stress conditions and structural anisotropy. Multiple strong earthquakes along the Tangshan fault zone predominantly occur within transitional zones between high-velocity and low-velocity anomalies. The Xingtai-Handan fault zone demonstrates concentrated seismic events likely triggered by lithospheric delamination processes associated with high-velocity anomalies.The dynamic mechanism of the destruction of the North China Craton is jointly dominated by lithospheric delamination, thermochemical erosion, and mantle convective erosion induced by the subduction of the Pacific plate, providing new geophysical constraints for understanding the stability evolution of the craton and the mechanism of strong earthquake propagation.
作者
王时
王亮
周依
王思思
WANG Shi;WANG Liang;ZHOU Yi;WANG Sisi(Hebei Earthquake Agency,262 Huaizhong Road,Shijiazhuang 050021,China;Hebei Hongshan National Observatory on Thick Sediments and Seismic Hazards,1540 West-Quanbei Street,Xingtai 054000,China;School of Artificial Intelligence,Hezhou University,3261 Xiaohe Road,Hezhou 542899,China)
出处
《大地测量与地球动力学》
北大核心
2025年第9期964-971,982,共9页
Journal of Geodesy and Geodynamics
基金
河北省地震科技星火计划(DZ2023120700006,DZ2024111400001,DZ2024112100001)
贺州学院博士科研启动基金(2023BSQD01)。
关键词
华北克拉通
双差层析成像
拆沉作用
软流圈物质上涌
north China Craton
double-difference tomography
delamination
upwelling of asthenosphere material
