A DISCUSSION ON THE SOURCE AND SEISMOGENIC STRUCTURE OF MS4.5 AND MS4.7 ZIGUI EARTHQUAKES IN 2014

doi:10.3969/j.issn.0253-4967.2015.03.005

Abstract

Abstract:

On 27 and 30 Mar. 2013, an M_S4.5 and M_S4.7 earthquake occurred at Zigui County of Hubei Province, which were two larger earthquakes in this region since the impoundment of the There Gorges Reservoir in 2003. Characteristics of the focal and seismogenic tectonic of the two earthquakes are analysed and discussed in this paper. Moment tensor solutions of two earthquakes are inverted by the Kiwi method which uses the wideband waveform of 13 stations from Hubei and Chongqing seismic network and a six-layer crustal velocity structure model. The inverted results show that there is a good fit between the observed waveform spectrum and theoretical waveform spectrum, and the non-fitting errors of two earthquakes are less than 0. 57. These indicate that the inversion results are reliable. Rupture modes of the earthquakes are both strike-slip with a small amount of thrust component, but the former earthquake is of sinistral strike-slip and the latter is the dextral one, and the fact that there is less DC component and more ISO component in their moment tensor solutions is likely the manifestation of the effect of the reservoir water on physical properties of crustal strata. More than 500 earthquakes from Mar. 27 to Apr. 27 in this sequence are relocated by Double-Difference Method using the waveform recording of 15 sub-stations from the Three Gorges Seismic Network, and the results show that aftershocks are distributed along NNW and NE, but mainly along NE direction. Two depth profiles along NNW and NE direction show that focal depths of the sequence are from 4.5 to 10km. Two significant planes in the deep strata are formed along NE direction by these aftershocks, which are in accord with the occurrence of the NE-striking nodal plane of the focal mechanisms. The field intensity survey points out that the isoseismal line of the intensity Ⅴ meizoseismal area is an ellipse, the major axis is along NNW direction and the minor axis is along NE direction. Combining the results of field intensity survey with the tectonic setting of the epicenter area, we deduce that the rupture plane along NE direction at the north of Xiannüshan Fault is the seismogenic fault plane of the two earthquakes, the distribution of aftershocks along NE and NNW, the shape of the seismogenic fault plane and the characteristic of the depth profiles all indicate that these earthquakes are controlled and influenced by Xiannüshan Fault and Jiuwanxi Fault.

Key words: moment tensor inversion, focal distribution, depth profiles, seismogenic structure

摘要：

2014年3月27日和30日湖北秭归县发生了三峡水库蓄水以来该地区最大的2次地震, 文中通过多种方法分析了2次地震的震源与发震构造特征.采用Kiwi方法反演2次地震的矩张量解, 该方法中使用了湖北和重庆测震台网14个宽频带波形记录和6层地壳速度结构模型, 反演结果显示, 2次地震观测谱和波形与理论谱和波形拟合得比较好, 非拟合误差数<0.57, 表明反演结果是可靠的.2次地震均为走滑兼少量逆冲错动, 但前一地震为左旋走滑, 后一地震为右旋走滑, 矩张量解中DC成分偏少而ISO成分多可能是库水对地下介质物性影响的反映.同时也使用三峡台网15个子台记录的波形资料, 采用双差定位法重新精定位了从3月27日至4月27日时段内超过500次地震序列事件, 结果显示余震序列分布方向为NNW向和NE向, 但主要集中在NE向, 并分别沿NNW和NE向作了深度剖面, 剖面显示震源深度为4.5~10.0km, 余震在深部呈现2个较明显的断面, 与震源机制解NE向节面产状一致.野外现场宏观烈度调查指出, Ⅴ度极震区等震线为一椭圆, 长轴NWW向, 短轴NE向, 结合野外现场考察结果和震源区地质构造背景, 综合推断仙女山断裂北端的NE向破裂面为2次地震的发震断面, 余震序列的NE和NNW向分布、剖面上发震层的形态和深度特征表明, 这次地震活动受到了仙女山断裂和九畹溪断裂活动的控制与影响.

关键词: 矩张量反演, 震中分布, 深度剖面, 发震构造

CLC Number:

P315.3⁺3

WU Hai-bo, YAO Yun-sheng, SHEN Xue-lin, ZHAO Ling-yun. A DISCUSSION ON THE SOURCE AND SEISMOGENIC STRUCTURE OF M_S4.5 AND M_S4.7 ZIGUI EARTHQUAKES IN 2014[J]. SEISMOLOGY AND GEOLOGY, 2015, 37(3): 719-730.

吴海波, 姚运生, 申学林, 赵凌云. 2014年秭归M_S4.5和M_S4.9地震震源与发震构造特征[J]. 地震地质, 2015, 37(3): 719-730.

References

毕珉峰, 楚全芝, 邓志辉, 等. 2012. 长江三峡地区仙女山断裂北端延伸问题探讨［J］. 地震地质, 34(2): 294—301. doi: 10.3969/j. issn.0253-4967.
BI Min-feng, CHU Quan-zhi, DENG Zhi-hui, et al. 2012. Tectonic landform and location of the northern end of Xiannüshan Fault at the Three Gorges area［J］. Seismology and Geology, 34(2): 294—301(in Chinese).
蔡晓刚, 姚陈, 陈晓非. 2011. 各向异性ATI介质剪切位错源地震矩张量［J］. 地球物理学报, 54(7): 1772—1782.
CAI Xiao-gang, YAO Chen, CHEN Xiao-fei. 2011. Seismic moment tensor in anisotropic ATI media: Shear faulting［J］. Chinese J Geophys, 54(7): 1772—1782(in Chinese).
陈学波, 陈步云, 张四维, 等. 1994. 长江三峡工程坝区及外围深度构造特征研究［M］.北京: 地震出版社. 1—29.
CHEN Xue-bo, CHEN Bu-yun, ZHANG Si-wei, et al. 1994. Study of Deep Tectonic Characteristics in the Yangtze-Three Gorges Dam and Adjacent Area［M］. Seismological Press, Beijing. 1—29(in Chinese).
高士钧. 1992. 长江三峡地区地壳应力场与地震［M］. 北京: 地震出版社. 15—32.
GAO Shi-jun. 1992. Crustal Stress Field and Earthquake in the Three Gorges Area［M］. Seismological Press, Beijing. 15—32(in Chinese).
李强, 赵旭, 蔡晋安, 等. 2009. 三峡水库坝址及邻区中上地壳P波速度结构［J］. 中国科学(D辑), 39(4): 427—436.
LI Qiang, ZHAO Xu, CAI Jin-an, et al. 2009. P-wave velocity structure of upper and middle crust beneath the Three Gorges reservoir dam and adjacent region［J］. Science in China(Ser D), 39(4): 427—436(in Chinese).
廖武林, 姚运生, 丁志峰, 等. 2007. 三峡地区P波速度层析成像研究［J］. 大地测量与地球动力学, 27(3): 80—84.
LIAO Wu-lin, YAO Yun-sheng, DING Zhi-feng, et al. 2007. Tomographic imagery of P wave velocity structure in Three Gorges region［J］. Journal of Geodesy and Geodynamics, 27(3): 80—84(in Chinese).
谭成轩. 1991. 长江三峡工程库首区仙女山断裂北延问题研究［J］. 水文地质工程地质, 18(5): 13—17.
TAN Cheng-xuan. 1991. Northward extension of Xiannüshan fault in the front region of Yangtze Gorges project［J］. Hydrogeology and Engineering Geology, 18(5): 13—17(in Chinese).
王墩, 姚运生, 薛军蓉, 等. 2007. 三峡水库重点监视区蓄水前后震源机制研究［J］. 大地测量与地球动力学, 27(5): 103—107.
WANG Dun, YAO Yun-sheng, XUE Jun-rong, et al. 2007. Focal mechanism of key monitoring area of Three Gorges reservoir before and after impoundment［J］. Journal of Geodesy and Geodynamics, 27(5): 103—107(in Chinese).
王瑞江, 谭成轩. 1995. 长江三峡地区仙女山断裂带构造活动性及其北延问题讨论［J］. 地球科学: 中国地质大学学报, 20(6): 693—696.
WANG Rui-jiang, TAN Cheng-xuan. 1995. A discussion of structural activity of Xiannüshan fault belt and its extension towards north in the Three Gorges on the Yangtze River［J］. Earth Science: Journal of China University of Geosciences, 20(6): 693—696(in Chinese).
王小龙, 马胜利, 郭志, 等. 2013. 利用地震背景噪声成像技术反演三峡库区及邻近地区地壳剪切波速度结构［J］. 地球物理学报, 56(12): 4113—4124.
WANG Xiao-long, MA Sheng-li, GUO Zhi, et al. 2013. S-wave velocity of the crust in Three Gorges reservoir and the adjacent region inverted from seismic ambient noise tomography［J］. Chinese J Geophys, 56(12): 4113—4124(in Chinese).
杨淑贤, 高士钧, 蔡永建, 等. 2005. 三峡及邻区新构造期以来应力场分区研究［J］. 大地测量与地球动力学, 25(4): 42—45.
YANG Shu-xian, GAO Shi-jun, CAI Yong-jian, et al. 2005. Study on stress field zoning in Three Gorges and its adjacent area since neotectonic age［J］. Journal of Geodesy and Geodynamics, 25(4): 42—45(in Chinese).
杨淑贤, 周明礼, 徐孝文, 等. 1993. 秭归盆地东缘断裂构造觅踪: 再论仙女山断裂带北延过长江问题［J］. 地壳形变与地震, 13(2): 48—54.
YANG Shu-xian, ZHOU Ming-li, XU Xiao-wen, et al. 1993. Seeking for east boundary fault structure at Zigui Basin: A further discussion on northward extension through Yangtze River of the Xiannüshan fault zone［J］. Crustal Deformation and Earthquake, 13(2): 48—54(in Chinese).
袁登维, 梅应堂, 秦兴黎, 等. 1996. 长江三峡工程坝区及外围地壳稳定性研究［M］. 武汉: 中国地质大学出版社. 42—65.
YUAN Deng-wei, MEI Ying-tang, QIN Xing-li, et al. 1996. Study of Crustal Stability in the Yangtze-Three Gorges Dam and Adjacent Area［M］. China University Geosciences Press, Wuhan. 42—65(in Chinese).
张毅, 陈超, 梁青, 等. 2012. 三峡地区中上地壳密度结构［J］. 地球科学: 中国地质大学学报, 37(增): 213—221.
ZHANG Yi, CHEN Chao, LIANG Qing, et al. 2012. Density structure of upper and middle crust in Three Gorges reservoir area［J］. Earth Science: Journal of China University of Geosciences, 37(Suppl): 213—221(in Chinese).
Cesca S, Heimann S, Dahm T. 2011. Rapid directivity detection by azimuthal amplitude spectra inversion［J］. J Seismol, 15(1): 147—164(submitted).
Cesca S, Heimann S, Stammler K, et al. 2010. Automated procedure for point and kinematic source inversion at regional distances［J］. Journal of Geophysical Research, 115(B6): B06304.
Dziewonski A M, Woodhouse J H. 1983. An experiment in the systematic study of global seismicity: Centroid moment tensor solutions for 201 moderate and large earthquakes of 1981［J］. J Geophys Res, 88: 3247—3271.
Kawakatsu H. 1995. Automated near-real time CMT inversion［J］. Geophys Res Lett, 22: 2569—2572.
Sipkin S A. 1982. Estimation of earthquake source parameters by the inversion of waveform data: Synthetic waveforms［J］. Phys Earth Planet Inter, 30: 242—259.
Sipkin S A. 1986. Estimation of earthquake source parameters by the inversion of waveform data: Global seismicity, 1981-1983［J］. Bull Seismol Soc Am, 76: 1515—1541.
Snoke J A, Munsey J W, Teague A C, et al. 1984. A program for focal mechanism determination by combined use of polarity and SV-P amplitude ratio data［J］. Earthquake Notes, 55(3): 1—15.
Thomsen L. 1986. Weak elastic anisotropy［J］. Geophysics, 51(10): 1954—1966.
Wang R. 1999. A simple orthonormalization method for the stable and efficient computation of Green's functions［J］. Bull Seismol Soc Am, 89: 733—741.
Zhang Z J, Bai Z M, Waiter M, et al. 2009. Crustal structure across the Three Gorges area of the Yangtze platform, central China, from seismic refraction/wide-angle reflection data［J］. Tectonophysics, 475(3-4): 423—437.

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