2017年6月16日湖北秭归M_S4.3地震成因初探
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摘要
北京时间2017年6月16日19时48分,湖北省秭归县发生M_S4.3地震(震中位置31.06°N, 110.48°E)。此次地震导致当地160多间建筑物出现不同程度损坏, 100多人生活受到影响,震区中危岩体出现一定程度破坏。分析此次地震的震源参数将有助于了解其震源特征和发震机制。本文首先获取了震中距在3°以内的40个宽频带固定台站的三分量数据,然后利用FK(Frequency wavenumber)方法计算了在不同深度下Crust2.0模型和改进的1-D模型的格林函数,分别使用Cut And Paste(CAP)方法反演得到本次地震的震源机制解和深度;并采用基阶Rayleigh波振幅谱进一步约束了质心深度。结果表明此次地震的最佳震源机制解的节面Ⅰ:68°/59°/163°;节面Ⅱ:166°/75°/32°,最佳矩震级为M_W4.3,最佳深度约为5 km。对比2013年巴东地震、 2014年秭归地震以及2011年湖北阳新—江西瑞昌地震的震源参数和余震信息,此次地震有可能是水库诱发地震,但要判断成因还需进一步研究。
Seismicity of the head portion of the three Gorges Reservoir region has increased obviously since the first impounding at the end of May, 2003. Most of the quakes are reservoir-induced, and mainly occurred on the Gaoqiao Fault west to the Zigui Basin, and the north end of the Xiannvshan Fault which locates between the Zigui Basin and Huangling Massif. The focal depths are usually less than 10 km, with the average of 4 km. Around UTC time 19:48 on June 16 th, 2017, a M_S4.3 earthquake occurred near Zigui county(31.06°N,110.48°E). This earthquake has damaged more than 160 houses, and caused some collapses of medium-risk rock. Analyzing source parameters of the M4.3 earthquake can help us learn its seismogenic mechanism and provide reference for reservoir induced earthquakes. In this study, we use a total of 40 three-component broadband seismic stations within an epicenter distance of less than 3°. Two velocity models, Crust 2.0, a modified 1-D equivalent model, and the frequency-wavenumber(FK) method have been adopted to calculate Green's Functions at different depths. We use the CAP algorithm to invert focal mechanism of the M_S4.3 earthquake for each model. We also use the fundamental-mode Rayleigh wave amplitude spectra to determine the centroid depth. The results show that the focal mechanism has the best solution of plane I: 68°/59°/163° and plane II: 166°/75°/32°. The moment magnitude is M_W4.3 and the centroid depth is around 5 km. By comparing the results with those for the 2013 Badong earthquake, the 2014 Zigui earthquake and the 2011 Yangxin—Ruichang earthquake, we infer that the M_S4.3 earthquake might be a reservoir induced earthquake, but further study is still needed to determine the detailed seismogenic mechanism.
Seismicity of the head portion of the three Gorges Reservoir region has increased obviously since the first impounding at the end of May, 2003. Most of the quakes are reservoir-induced, and mainly occurred on the Gaoqiao Fault west to the Zigui Basin, and the north end of the Xiannvshan Fault which locates between the Zigui Basin and Huangling Massif. The focal depths are usually less than 10 km, with the average of 4 km. Around UTC time 19:48 on June 16 th, 2017, a M_S4.3 earthquake occurred near Zigui county(31.06°N,110.48°E). This earthquake has damaged more than 160 houses, and caused some collapses of medium-risk rock. Analyzing source parameters of the M4.3 earthquake can help us learn its seismogenic mechanism and provide reference for reservoir induced earthquakes. In this study, we use a total of 40 three-component broadband seismic stations within an epicenter distance of less than 3°. Two velocity models, Crust 2.0, a modified 1-D equivalent model, and the frequency-wavenumber(FK) method have been adopted to calculate Green's Functions at different depths. We use the CAP algorithm to invert focal mechanism of the M_S4.3 earthquake for each model. We also use the fundamental-mode Rayleigh wave amplitude spectra to determine the centroid depth. The results show that the focal mechanism has the best solution of plane I: 68°/59°/163° and plane II: 166°/75°/32°. The moment magnitude is M_W4.3 and the centroid depth is around 5 km. By comparing the results with those for the 2013 Badong earthquake, the 2014 Zigui earthquake and the 2011 Yangxin—Ruichang earthquake, we infer that the M_S4.3 earthquake might be a reservoir induced earthquake, but further study is still needed to determine the detailed seismogenic mechanism.
引文
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[12] Zhu L,Helmberger D V.Advancement in source estimation techniques using broadband regional seismograms[J].Bulletin of the Seismological Society of America,1996,86(5):1634-1641.
[13] Zhu L,Rivera L A.A note on the dynamic and static displacements from a point source in multilayered media[J].Geophysical Journal International,2002,148(3):619-627.
[14] 张国民,李丽,马宏生,等.中国大陆地震震源深度及其构造含义[J].科学通报,2002(09):663-668.
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[18] Spence W.Relative epicenter determination using P-wave arrival-time differences[J].Bulletin of the Seismological Society of America,1980,70(1):171-183.
[19] 崇加军,倪四道,曾祥方.sPL,一个近距离确定震源深度的震相[J].地球物理学报,2010,53(11):2620-2630.
[20] 罗艳,曾祥方,倪四道.震源深度测定方法研究进展[J].地球物理学进展,2013,28(05):2309-2321.
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[22] Tsai Y B,Aki K.Precise focal depth determination from amplitude spectra of surface waves[J].Journal of Geophysical Research,1970,75(29):5729-5744.
[23] Nguyen B,Herrmann R.Determination of source parameters for central and eastern North American earthquakes (1982—1986)[J].Seismological Research Letters,1992,63(4):567-586.
[24] Fox B D,Selby N D,Heyburn R,et al.Shallow seismic source parameter determination using intermediate-period surface wave amplitude spectra[J].Geophysical Journal International,2012,191(2):601-615.
[25] Heyburn R,Selby N D,Fox B.Estimating earthquake source depths by combining surface wave amplitude spectra and teleseismic depth phase observations[J].Geophysical Journal International,2013,194(2):1000-1010.
[26] 赵博,高原,马延路.利用面波振幅谱确定四川九寨沟M7.0地震震源深度[J].科学通报,2018,63(13):1223-1234.
[27] 郑秀芬,欧阳飚,张东宁,等.“国家数字测震台网数据备份中心”技术系统建设及其对汶川大地震研究的数据支撑[J].地球物理学报,2009,52(05):1412-1417.
[28] 汪健,申重阳,李辉,等.三峡坝区深部界面重力反演[J].大地测量与地球动力学,2012,32(05):6-11.
[29] 汪健,申重阳,李辉,等.三峡地区壳幔深部界面重力反演[J].地震学报,2014,36(01):70-83.
[30] 李强,赵旭,蔡晋安,等.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:地球科学),2009,39(04):427-436.
[31] 李强,赵旭,蔡晋安,等.三峡水库坝址及邻区中上地壳S波速度结构[J].地震学报,2011,33(01):39-50.
[32] Herrmann R B.Computer programs in seismology:An evolving tool for instruction and research[J].Seismological Research Letters,2013,84(6):1081-1088.
[33] 申学林,王秋良,魏贵春,等.基于近台数据的2017-06巴东M4.3地震序列震源深度研究[J].大地测量与地球动力学,2018,38(01):14-17.
[34] 董彦君,王秋良,申学林,等.sPL震相在巴东M4.3地震序列震源深度测定中的应用[J].大地测量与地球动力学,2018,38(03):221-224.
[35] 赵凌云,王杰,陈俊华,等.2014年秭归M4.7、 M4.5地震序列与2017年秭归—巴东M4.3、 M4.1地震序列对比研究[J].大地测量与地球动力学,2018,38(03):233-238.
[36] Wei S,Konca A,Luo Y,et al,Regional wave propagation beneath western US,2008 IRIS Workshop,poster.
[37] 孟庆君,倪四道,韩立波,等.地壳速度结构对极浅源地震深度反演的影响——以荣昌地震为例[J].中国地震,2014,30(04):490-500.
[38] 张曙光,王俊.长江三峡工程水文泥沙年报(2016)[M].中国三峡出版社,2017.9.
[39] 赵凌云,邓津,陈俊华,等.基于CAP方法的震源机制研究[J].长江科学院院报,2010,27(05):81-84.
[40] 陈蜀俊,姚运生,吴建超,等.巴东MS5.1地震——一种新的水库地震类型[J].大地测量与地球动力学,2014,34(03):1-5.
[41] 张丽芬,廖武林,李井冈,等.2013年12月16日巴东M5.1地震序列及发震构造分析[J].地震地质,2016,38(03):747-759.
[42] 吴海波,姚运生,申学林,等.2014年秭归MS4.5和MS4.9地震震源与发震构造特征[J].地震地质,2015,37(03):719-730.
[43] 王秋良,张丽芬,廖武林,等.2014年3月湖北省秭归县M4.2、 M4.5地震成因分析[J].地震地质,2016,38(01):121-130.
[44] 王向腾,李志伟,包丰,等.2011年9月10日瑞昌—阳新地震发震构造初探[J].地震地磁观测与研究,2014,35(Z1):15-21.
[45] 张丽芬,姚运生,廖武林.2011年MS4.6瑞昌—阳新地震的震源机制及发震构造探讨[J].地震地质,2013,35(02):290-299.
[46] 陈俊华,申学林,赵凌云,等.2011年9月10日瑞昌、 阳新间M4.6地震序列特征分析[J].地震地磁观测与研究,2013,34(Z1):15-19.
[47] 雷东宁,陈俊华,张丽芬,等.湖北巴东MS5.1地震构造背景分析[J].大地测量与地球动力学,2014,34(03):6-9.
[2] 马文涛,徐长朋,李海鸥,等.长江三峡水库诱发地震加密观测及地震成因初步分析[J].地震地质,2010,32(4):552-563.
[3] 黄荣,朱露培,徐义贤,等.利用震源机制和精定位研究三峡库首区活动断裂特征[A].2015中国地球科学联合学术年会论文集(十)——专题28电磁地球物理学研究应用及其新进展、 专题29盆地动力学与能源、 专题30活动断层、 地震构造与深部结构[C].2015.
[4] 王墩,姚运生,薛军蓉,等.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,2007,27(5):103-107.
[5] 宋琛,王墩.三峡水库蓄水后小微震事件的震源机制及成因分析[J].大地测量与地球动力学,2016,36(7):625-629.
[6] 王秋良,张丽芬,廖武林,等.三峡库首区断裂构造与地震活动特征[J].大地测量与地球动力学,2013,33(5):29-33.
[7] Huang R,Zhu L,Encarnacion J,et al.Seismic and Geologic Evidence of Water-Induced Earthquakes in the Three Gorges Reservoir Region of China[J].Geophysical Research Letters,45.https://doi.org/10.1029/2018GL099639.
[8] Zhao L S,Helmberger D V.Source estimation from broadband regional seismograms[J].Bulletin of the Seismological Society of America,1994,84(1):91-104.
[9] Nakanishi I,Kanamori H.Source mechanisms of twenty-six large,shallow earthquakes (MS≥6.5) during 1980 from P-wave first motion and long-period Rayleigh wave data[J].Bulletin of the Seismological Society of America,1984,74:805-818
[10] 张项,陈棋福,赵里,等.用P波初动波形求解中小地震震源机制解[J].中国地震,2010,26(3):273-282.
[11] Dziewonski A M,Chou T A,Woodhouse J H.Determination of earthquake source parameters from waveform data for studies of global and regional seismicity[J].Journal of Geophysical Research:Solid Earth,1981,86(B4):2825-2852.
[12] Zhu L,Helmberger D V.Advancement in source estimation techniques using broadband regional seismograms[J].Bulletin of the Seismological Society of America,1996,86(5):1634-1641.
[13] Zhu L,Rivera L A.A note on the dynamic and static displacements from a point source in multilayered media[J].Geophysical Journal International,2002,148(3):619-627.
[14] 张国民,李丽,马宏生,等.中国大陆地震震源深度及其构造含义[J].科学通报,2002(09):663-668.
[15] 倪四道.大陆地震震源深度测定方法研究进展[A].中国地球物理学会,中国地球物理2012[C].中国地球物理学会,2012:1.
[16] Geiger L.Probability method for the determination of earthquake epicenters from the arrival time only[J].Bull.St.Louis Univ,1912,8(1):56-71.
[17] Douglas A.Joint epicenter determination[J].Nature,1967,215(5096):47-48.
[18] Spence W.Relative epicenter determination using P-wave arrival-time differences[J].Bulletin of the Seismological Society of America,1980,70(1):171-183.
[19] 崇加军,倪四道,曾祥方.sPL,一个近距离确定震源深度的震相[J].地球物理学报,2010,53(11):2620-2630.
[20] 罗艳,曾祥方,倪四道.震源深度测定方法研究进展[J].地球物理学进展,2013,28(05):2309-2321.
[21] Jia Z,Ni S,Chu R,et al.Joint inversion for earthquake depths using local waveforms and amplitude spectra of Rayleigh waves[J].Pure and Applied Geophysics,2017,174(1):261-277.
[22] Tsai Y B,Aki K.Precise focal depth determination from amplitude spectra of surface waves[J].Journal of Geophysical Research,1970,75(29):5729-5744.
[23] Nguyen B,Herrmann R.Determination of source parameters for central and eastern North American earthquakes (1982—1986)[J].Seismological Research Letters,1992,63(4):567-586.
[24] Fox B D,Selby N D,Heyburn R,et al.Shallow seismic source parameter determination using intermediate-period surface wave amplitude spectra[J].Geophysical Journal International,2012,191(2):601-615.
[25] Heyburn R,Selby N D,Fox B.Estimating earthquake source depths by combining surface wave amplitude spectra and teleseismic depth phase observations[J].Geophysical Journal International,2013,194(2):1000-1010.
[26] 赵博,高原,马延路.利用面波振幅谱确定四川九寨沟M7.0地震震源深度[J].科学通报,2018,63(13):1223-1234.
[27] 郑秀芬,欧阳飚,张东宁,等.“国家数字测震台网数据备份中心”技术系统建设及其对汶川大地震研究的数据支撑[J].地球物理学报,2009,52(05):1412-1417.
[28] 汪健,申重阳,李辉,等.三峡坝区深部界面重力反演[J].大地测量与地球动力学,2012,32(05):6-11.
[29] 汪健,申重阳,李辉,等.三峡地区壳幔深部界面重力反演[J].地震学报,2014,36(01):70-83.
[30] 李强,赵旭,蔡晋安,等.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:地球科学),2009,39(04):427-436.
[31] 李强,赵旭,蔡晋安,等.三峡水库坝址及邻区中上地壳S波速度结构[J].地震学报,2011,33(01):39-50.
[32] Herrmann R B.Computer programs in seismology:An evolving tool for instruction and research[J].Seismological Research Letters,2013,84(6):1081-1088.
[33] 申学林,王秋良,魏贵春,等.基于近台数据的2017-06巴东M4.3地震序列震源深度研究[J].大地测量与地球动力学,2018,38(01):14-17.
[34] 董彦君,王秋良,申学林,等.sPL震相在巴东M4.3地震序列震源深度测定中的应用[J].大地测量与地球动力学,2018,38(03):221-224.
[35] 赵凌云,王杰,陈俊华,等.2014年秭归M4.7、 M4.5地震序列与2017年秭归—巴东M4.3、 M4.1地震序列对比研究[J].大地测量与地球动力学,2018,38(03):233-238.
[36] Wei S,Konca A,Luo Y,et al,Regional wave propagation beneath western US,2008 IRIS Workshop,poster.
[37] 孟庆君,倪四道,韩立波,等.地壳速度结构对极浅源地震深度反演的影响——以荣昌地震为例[J].中国地震,2014,30(04):490-500.
[38] 张曙光,王俊.长江三峡工程水文泥沙年报(2016)[M].中国三峡出版社,2017.9.
[39] 赵凌云,邓津,陈俊华,等.基于CAP方法的震源机制研究[J].长江科学院院报,2010,27(05):81-84.
[40] 陈蜀俊,姚运生,吴建超,等.巴东MS5.1地震——一种新的水库地震类型[J].大地测量与地球动力学,2014,34(03):1-5.
[41] 张丽芬,廖武林,李井冈,等.2013年12月16日巴东M5.1地震序列及发震构造分析[J].地震地质,2016,38(03):747-759.
[42] 吴海波,姚运生,申学林,等.2014年秭归MS4.5和MS4.9地震震源与发震构造特征[J].地震地质,2015,37(03):719-730.
[43] 王秋良,张丽芬,廖武林,等.2014年3月湖北省秭归县M4.2、 M4.5地震成因分析[J].地震地质,2016,38(01):121-130.
[44] 王向腾,李志伟,包丰,等.2011年9月10日瑞昌—阳新地震发震构造初探[J].地震地磁观测与研究,2014,35(Z1):15-21.
[45] 张丽芬,姚运生,廖武林.2011年MS4.6瑞昌—阳新地震的震源机制及发震构造探讨[J].地震地质,2013,35(02):290-299.
[46] 陈俊华,申学林,赵凌云,等.2011年9月10日瑞昌、 阳新间M4.6地震序列特征分析[J].地震地磁观测与研究,2013,34(Z1):15-19.
[47] 雷东宁,陈俊华,张丽芬,等.湖北巴东MS5.1地震构造背景分析[J].大地测量与地球动力学,2014,34(03):6-9.