冷龙岭地区2016年青海门源6.4级地震发震构造特征

发布时间：2018-03-13 12:32

本文选题：门源地震　切入点：冷龙岭断裂带　出处：《地震地质》2017年03期 　论文类型：期刊论文

【摘要】：青海门源北部的冷龙岭断裂带于2016年发生M_S6.4地震,该地震与1986年发生的另一次M_S6.4地震的震源机制解截然不同,并且二者与冷龙岭主断层几乎表现为纯左旋走滑的性质也差异很大。为明确2次地震的发震构造特征,分析二者与冷龙岭主断层的关系,利用Sentinel-1A数据干涉处理得到了2016年地震的同震形变场,并结合高分辨率影像、余震精定位及GPS资料对断层构造样式及地震构造特征进行了研究。研究结果表明,2016年地震发生在冷龙岭断裂带西段北侧的分支断层上,地震造成分支断层两侧发生背斜式褶曲隆升。2次地震分别发生在分支断层的东西两端,其两端分别向冷龙岭主断层弯曲收敛并交会,在平面上形成左行右阶与左行左阶的几何结构,在区域整体剪切环境下,分别发生剪切挤压与剪切拉张,因而造成2次地震的震源机制解分别表现为压性与张性为主又兼具一定的走滑性质,综合认为分支断层与主断层之间的构造组合样式是导致2个不同震源机制解的主要因素。2次地震活动皆反映了冷龙岭断裂带整体表现为左旋走滑运动特征,该构造变形机制也体现了祁连-海原构造带对青藏高原东北缘的构造调节作用,即来自于青藏板块的构造运动在受到北部戈壁-阿拉善块体及东部华北克拉通块体的阻挡后,在青藏高原东北缘通过一系列左旋走滑断裂的调节,构造运动方向逐渐发生顺时针旋转。门源地震使得对冷龙岭断裂带地震地质问题的深入研究更加紧迫。
[Abstract]:The MS6.4 earthquake occurred in the Lenglongling fault zone in the northern part of Mengyuan, Qinghai on 2016. The earthquake is quite different from the focal mechanism of another MS6.4 earthquake that occurred in 1986. In order to clarify the seismogenic characteristics of the two earthquakes, the relationship between the two faults and the Lenglongling main fault is analyzed. The coseismic deformation field of the 2016 earthquake was obtained by using Sentinel-1A data interferometry, and combined with high resolution image. The fine location of aftershocks and GPS data are used to study the structural style and seismic characteristics of the faults. The results show that the earthquake of 2016 occurred on a branch fault in the northern part of the Lenglongling fault zone. The earthquake caused the anticline fold uplift to occur on both sides of the branch fault. 2 earthquakes occurred at the east and west ends of the branch fault, which converged to the main fault of Lenglongling and converged. The geometric structure of left row, right order and left row left order is formed on the plane, and shear extrusion and shearing tension occur respectively in the whole shear environment of the region. As a result, the focal mechanism solutions of the two earthquakes are mainly compressive and tensional, and have both strike-slip properties. It is considered that the structural combination style between the branch fault and the main fault is the main factor leading to the solution of two different focal mechanisms. The seismic activities of .2 times all reflect the overall left-lateral strike-slip movement characteristics of the Lenglongling fault zone as a whole. The tectonic deformation mechanism also reflects the tectonic adjustment of the Qilian Haiyuan tectonic belt to the northeastern margin of the Qinghai-Tibet Plateau, that is, the tectonic movement from the Qinghai-Tibet plate is blocked by the Gobi Alashan block in the north and the North China craton block in the east. By adjusting a series of left-lateral strike-slip faults in the northeastern margin of Qinghai-Xizang Plateau, the direction of tectonic movement gradually rotates clockwise. The Menyuan earthquake makes it more urgent to study the seismic geological problems in the Lenglongling fault zone.
【作者单位】：中国地震局地质研究所;中国地震局地壳应力研究所地壳动力学重点实验室;
【基金】：中国地震局地壳应力研究所基本科研业务专项(ZDJ201516,ZDJ201515);中国地震局地震行业科研专项(201408023)共同资助
【分类号】：P315.2

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