2014年9月晋冀蒙临时地震台网正式运行,为晋冀蒙交界地区的地震研究提供了丰富的资料。结合临时台与固定台记录的P波走时资料,采用双差层析成像方法对该区进行地震重定位和三维P波速度结构联合反演,分析该区3个典型盆地的速度扰动结果,结果表明,地震重定位残差显著降低,震源深度分布更加合理;P波速度浅层基本符合平原地区低速、山区高速的特点,深层则有相反表现,典型盆地P波速度在浅层较为复杂,高低速相间,深层表现为低速;研究时段内忻定盆地和延怀盆地地震活动密集,大同盆地地震活动较弱,低速体及边缘地震活动强度高于高速体及边缘。
September 2014, a temporary station network in the juncture area of Shanxi, Hebei and Inner Mongolia was officially put in operation, which provided abundant information for the earthquake research in the area. We did joint inversion of seismic relocation and 3D P-wave velocity structure by double-difference tomography combined with P-wave arrival time data recorded by the temporary stations and the fixed stations in the area. The velocity perturbation results of three typical basins in the area were analyzed. The results show that the residual of seismic relocation is significantly reduced and the distribution of focal depth is more reasonable. The P-wave velocity in shallow is basically consistent with the characteristic that the plain is low velocity area and the mountain is high velocity area, while the reverse in deep. The P-wave velocity in shallow of the typical basin is more complicated, high and low velocity alternatively, and the deep shows low velocity. The seismic activity is dense in the Xinding basin and the Yanhuai basin, and the seismic activity in the Datong basin is weak. The seismic activity in low velocity body and its edge is higher than that in high velocity body and its edge.
2018,39(2): 10-17 收稿日期:2017-11-08
DOI:10.3969/j.issn.1003-3246.2018.02.002
基金项目:河北省地震局地震科技星火计划(项目编号:DZ20160621076);河北省地震局地震科技星火计划(项目编号:DZ20170109002);中国地震局2017年度震情跟踪定向工作任务(项目编号:2017020104)
作者简介:陈婷(1990-),女,助理工程师,主要从事地震活动性和中长期预测工作
*通讯作者:王晓山(1980-),男,副研究员,主要从事数字地震学工作
参考文献:
邓文泽, 陈九辉, 郭飚, 等. 龙门山断裂带精细速度结构的双差层析成像研究[J]. 地球物理学报, 2014, 57 (4):1 101-1 110.
冯向东, 王晓山, 陈婷, 等. 晋冀蒙交界地区最小一维速度模型[J]. 华北地震科学, 2017, 35 (4):16-21.
吕子强, 郑建常, 张刚, 等. 濮阳地震集中区双差层析成像研究[J]. 地震研究, 2016, 39 (2):255-260.
王伟平. 鲜水河、安宁河和龙门山断裂带交汇区双差层析成像研究[D]. 北京:中国地震局地球物理研究所, 2016.
王想, 冯向东, 平建军. 晋冀蒙交界地区地震时间序列谱的分析与研究[J]. 地震地磁观测与研究, 2010, 31 (6):14-19.
王小娜. 川滇地区地震重定位及 P 波速度结构研究[D]. 北京:中国科学院大学, 2015.
武敏捷,朱红彬,林向东,等. 由多地震活动参数分析晋冀蒙交界地区长期地震危险性[J]. 地震地磁观测与研究, 2014, 35 (3/4):57-62.
于湘伟, 陈运泰, 王培德. 京津唐地区中上地壳三维 P 波速度结构[J]. 地震学报, 2003, 25 (1):1-14.
朱红彬, 李红, 武敏捷, 等. 晋冀蒙交界中强地震前的中等地震平静-活跃-平静演化[J]. 地球物理学进展, 2014, 29 (3):1 114-1 120.
Huang JL, Zhao D. Crustal heterogeneity and seismotectonics of the region around Beijing, China[J]. Tectonophysics, 2004, 385(1/4):159-180.
Humphreys E, Clayton R W. Adaptation of back projection tomography to seismic travel time problems[J]. Journal of Geophysical Research Solid Earth, 1988, 93(B2):1 073-1 085.
Kissling E, Ellsworth W L, Eberhart-Phillips D, et al. Initial reference models in local earthquake tomography[J]. Journal of Geophysical Research Solid Earth, 1994, 99(B10):19 635-19 646.
Spakman W, Lee S V D, Hilst R V D. Travel-time tomography of the European-Mediterranean mantle down to 1 400 km[J]. Physics of the Earth & Planetary Interiors, 1993, 79(1/2):3-74.
Zhang HJ, Thurber C H. Double-Difference Tomography:The Method and Its Application to the Hayward Fault, California[J]. Bulletin of the Seismological Society of America, 2003, 93(5):1 875-1 889.