王椿镛, 段永红, 吴庆举, 王志铄. 2016: 华北强烈地震深部构造环境的探测与研究. 地震学报, 38(4): 511-549.
引用本文: 王椿镛, 段永红, 吴庆举, 王志铄. 2016: 华北强烈地震深部构造环境的探测与研究. 地震学报, 38(4): 511-549.
Wang Chunyong, Duan Yonghong, Wu Qingju, Wang Zhishuo. 2016: Exploration on the deep tectonic environment of strong earthquakes in North China and relevant research findings. Acta Seismologica Sinica, 38(4): 511-549.
Citation: Wang Chunyong, Duan Yonghong, Wu Qingju, Wang Zhishuo. 2016: Exploration on the deep tectonic environment of strong earthquakes in North China and relevant research findings. Acta Seismologica Sinica, 38(4): 511-549.

华北强烈地震深部构造环境的探测与研究

Exploration on the deep tectonic environment of strong earthquakes in North China and relevant research findings

  • 摘要: 20世纪六七十年代以来, 华北地区发生了一系列强烈地震. 强烈地震的孕育、 发生和发展与深部构造密切相关. 近50年来, 我国地震科学领域在强烈地震的地震构造和深部环境方面开展了大量的研究. 深部地球物理探测和地震层析成像结果揭示了华北地区地壳结构的基本特征, 并在强烈地震发生的深部构造环境等问题上取得了重要进展. 本文在回顾华北地区地壳上地幔结构探测的基础上, 对1966年邢台MS7.2, 1976年唐山MS7.8, 1975年海城MS7.3和1679年三河—平谷M8.0地震的地震构造和深部构造环境进行评述. 深部地球物理数据的综合分析表明, 震源下方的低速异常带, 高角度超壳深断裂, 地壳深浅构造的不一致, 偏低的上地幔顶部速度和局部隆起的莫霍界面, 是华北伸展构造区深部孕震环境的共同特征.

     

    Abstract: In the 1960--1970s,North China has undergone a series of strong earthquakes. The nucleation,development and occurrence mechanisms of strong earthquakes are closely related to the deep structure. For nearly 50 years,Chinese seismologists have carried out a great deal of researches in the fields of seismotectonics and deep environment of strong earthquakes. Deep geophysical survey and seismic tomography imaging revealed the basic characteristics of crustal structures in North China,and significant progresses have been made in the issues of the deep tectonic environment of strong earthquake occurrence. Based on the large-scale exploration of crustal and upper mantle structures in North China,this paper presents a review on the study of the seismotectonics and deep environment of 1966 Xingtai MS7.2,1976 Tangshan MS7.8,1975 Haicheng MS7.3 and 1679 Sanhe-Pinggu M8.0 earthquakes. Deep seismic reflection profilings revealed that there is a high-angle deep fault in the vicinity of focal source,which passes through lower crust to the Moho. The geometry of high-angle deep fault is basically consistent with the seismic fault plane of the focal mechanism solutions,thus it is considered as the seismogenic fault. A new model of the relation between shallow and deep structures is that the shallow listric normal fault and its related tectonic system of active graben and half graben only developed above the detachment in mid-crust,while the high-angle deep active fault or ductility deformation zone developed below. The tectonic model of Xingtai earthquakes has resolved the contradiction between the typical continental extensional tectonic environment and the strike-slip focal mechanism of strong earthquakes in North China. Based on the massive broadband seismic data in North China,seismic tomography shows that most of large earthquakes occurred in the transition between the high-velocity and low-velocity zones. Comprehensive analysis of deep geophysical data reveals that the low-velocity anomaly belt beneath the source,high-angle ultracrustal deep fault,inconsis-tency of the deep and shallow structures in crust,lower-velocity in the uppermost mantle,and local Moho uplift are the seismogenic environment features held in common by strong earthquakes in the extensional tectonic region of North China. The migration and deformation of the mantle material would contribute to the energy accumulation of a large earthquake,which leads to the Tangshan earthquake occurrence. The hypothesis of the "solid body" seismo-genic model extends the ideas to address the seismogenic environment of strong earthquakes. However,despite the deep seismic reflection profiling and the seismic tomography research greatly enriched the knowledge of seismogenic environment in deep,we still face some deep-seated problems which need further research.

     

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