Isoseismal line of Sichuan Changning MS6.0 earthquake in 2019 based on precisely located aftershocks sequence
-
摘要: 采用双差定位法对四川长宁MS6.0主震和24小时内的余震进行重新定位，对重定位的余震进行震级加权的方向分布拟合得到余震区的长轴和中心点，并与Ⅶ度烈度等震线长轴和等震线几何中心进行比较，结果显示：余震区长轴方向与Ⅶ度区长轴方向相近（差值为4°），且长度近似相等（差值为4 km）；余震中心与等震线中心均位于重定位主震的西北方向，且等震线中心相对余震中心向上盘方向偏移约3.0 km。长宁MS6.0地震等震线图呈现出明显的上/下盘效应，上盘高烈度区面积约为下盘的2.1倍，等震线中心也向上盘方向偏移。两小时和24小时的余震方向分布拟合具有很好的一致性，拟合结果与等震线具有相同规律。研究成果可为浅源中强震预评估烈度图的修正提供一种思路。Abstract: The double-difference location method was utilized to determine the locations of the main shock of Changning MS6.0 earthquake in Sichuan Province and its aftershocks within 24 hours. A magnitude-weighted direction distribution fitting for the relocated aftershocks results in the major axis and the center of aftershock area. A comparison with the major axis and geometric center of the isoseismal line of intensity Ⅶ shows that the directions of major axis between the aftershock area and the Ⅶ intensity area are close to each other （with a difference of 4°）, and the length of the two axes are approximately equal （with a difference of 4 km）. Furthermore, the centers of the aftershock area and isoseismal line both locate northwest of the relocated main shock, and the isoseismal center deviates towards the hanging wall from the center of the aftershock area with a distance of about 3.0 km. The isoseismal map of Changning MS6.0 earthquake shows visible hanging wall/footwall effects, i.e., the high-intensity area of the hanging wall is almost 2.1 times larger than that of the footwall, and the isoseismal center shifts towards the hanging wall. The fitting result of the aftershocks within 2 hours is consistent with that of 24 hours, and the comparison with isoseismal map results in the same conclusion. The results of this research might provide a new idea for the revision of the pre-assessment intensity map for shallow-source moderate-strong earthquakes.
-
-
![]()
图 1 长宁MS6.0地震矩心矩张量反演结果 （邹立晔等，2019）
Figure 1. Inversion results of centroid moment tensor for Changning MS6.0 earthquake （after Zou et al，2019）
![]()
图 2 长宁MS6.0地震序列重定位所用台站分布
Figure 2. Distribution of seismic stations for relocation of Changning MS6.0 earthquake sequence
![]()
图 3 四川东部P波速度模型（赵珠和张润生，1987）
Figure 3. P velocity model in eastern Sichuan （after Zhao， Zhang，1987）
![]()
图 4 长宁MS6.0震后24小时余震精定位结果
Figure 4. Relocated aftershocks within 24 hours after Changning MS6.0 earthquake
![]()
图 5 长宁MS6.0地震震后24小时余震深度分布
（a） 沿余震区长轴方向的震源深度剖面AA′ （剖面线两侧各取3 km）；（b）—（d） 垂直于余震区长轴方向的震源深度剖面BB′ ，CC′ 和DD′ （剖面线两侧各取5 km）
Figure 5. Depth distribution of aftershocks within 24 hours for Changning MS6.0 earthquake
（a） Vertical cross-section AA′ along the major-axis of the aftershock area （Projection width for each side is 3 km）；（b）−（d） Vertical cross-sections BB′ ，CC′ and DD′ that are perpendicular to the major-axis of the aftershock area （Projection width for each side is 5 km for each section）
![]()
图 6 长宁MS6.0地震震后24小时精定位余震区与等震线图的比较
Figure 6. Comparison of relocated aftershocks area within 24 hours with isoseismal map of Changning MS6.0 earthquake
![]()
图 7 长宁MS6.0地震震后2小时余震精定位结果
Figure 7. Relocated aftershocks within 2 hours after Changning MS6.0 earthquake
![]()
图 8 长宁MS6.0地震震后2小时余震深度分布
（a） AA′ 剖面线沿椭圆长轴方向，两侧各取3 km；（b） BB′ 剖面线垂直于长轴方向，两侧各取5 km
Figure 8. Depth distribution of aftershocks within two hours for Changning MS6.0 earthquake
（a） AA′ indicates the direction along the major-axis of the ellipse with projection width for each side of 3 km；（b） BB′ indicates the direction perpendicular to the major-axis of the ellipse with projection width for each side of 5 km
-
白仙富,戴雨芡,李永强,朱月芬,白世达,厉建明. 2011. 基于余震信息的宏观震中和影响场方向快速判定方法:以云南地区为例[J]. 地震研究,34(4):525–532. doi: 10.3969/j.issn.1000-0666.2011.04.020 Bai X F,Dai Y Q,Li Y Q,Zhu Y F,Bai S D,Li J M. 2011. Rapid assessment of the macro-epicenter and earthquake-effected field based on aftershocks:A case study of Yunnan area[J]. Journal of Seismological Research,34(4):525–532 (in Chinese).
韩渭宾,蒋国芳. 2010. 强震等震线、余震区形状与地震构造关系的研究[J]. 地震,30(4):32–39. doi: 10.3969/j.issn.1000-3274.2010.04.004 Han W B,Jiang G F. 2010. Study on the relation between isoseismic line,aftershock area of strong earthquakes and their seismotectonic environments[J]. Earthquake,30(4):32–39 (in Chinese).
蒋海昆,郑建常,吴琼,曲延军,李永莉,代磊. 2007. 中国大陆中强以上地震余震分布尺度的统计特征[J]. 地震学报,29(2):151–164. doi: 10.3321/j.issn:0253-3782.2007.02.004 Jiang H K,Zheng J C,Wu Q,Qu Y J,Li Y L,Dai L. 2007. Statistical features of aftershock distribution size for moderate and large earthquakes in Chinese mainland[J]. Acta Seismologica Sinica,29(2):151–164 (in Chinese).
李志强,袁一凡,李晓丽,何萍. 2008. 对汶川地震宏观震中和极震区的认识[J]. 地震地质,30(3):768–777. doi: 10.3969/j.issn.0253-4967.2008.03.015 Li Z Q,Yuan Y F,Li X L,He P. 2008. Some insights into the macro-epicenter and meizoseismal region of Wenchuan earthquake[J]. Seismology and Geology,30(3):768–777 (in Chinese).
四川省地震局. 2019. 四川长宁6.0级地震烈度图发布[EB/OL]. [2019−06−20]. http://www.scdzj.gov.cn/xwzx/fzjzyw/201906/t20190620_51770.html. Sichuan Earthquake Agency. 2019. Intensity distribution map of the Sichuan Changning MS6.0 earthquake[EB/OL]. [2019−06−20]. http://www.scdzj.gov.cn/xwzx/fzjzyw/201906/t20190620_51770.html （in Chinese）.
王栋. 2010. 近断层地震动的上/下盘效应研究[D]. 哈尔滨: 中国地震局工程力学研究所: 13−40. Wang D. 2010. The Hanging Wall/Footwall Effects of Near-Fault Ground Motions[D]. Harbin: Institute of Engineering Mechanics, China Earthquake Administration: 13−40 （in Chinese）.
王伟锞,李志强,李晓丽. 2011. 利用余震法快速判定宏观震中的研究[J]. 震灾防御技术,6(1):36–48. doi: 10.3969/j.issn.1673-5722.2011.01.004 Wang W K,Li Z Q,Li X L. 2011. Rapid determination of macro epicenter based on aftershocks[J]. Technology for Earthquake Disaster Prevention,6(1):36–48 (in Chinese).
王晓青,丁香,王龙,王岩. 2009. 四川汶川8级大地震灾害损失快速评估研究[J]. 地震学报,31(2):205–211. doi: 10.3321/j.issn:0253-3782.2009.02.010 Wang X Q,Ding X,Wang L,Wang Y. 2009. A study on fast earthquake loss assessment and its application to 2008 Wenchuan M8 earthquake[J]. Acta Seismologica Sinica,31(2):205–211 (in Chinese).
鄢家全,李金臣,俞言祥,潘华,郝玉芹. 2010. 论宏观震中及其快速估定方法[J]. 震灾防御技术,5(4):409–417. doi: 10.3969/j.issn.1673-5722.2010.04.003 Yan J Q,Li J C,Yu Y X,Pan H,Hao Y Q. 2010. Discussion of the macro-epicenter and the method of rapid estimation[J]. Technology for Earthquake Disaster Prevention,5(4):409–417 (in Chinese).
杨天青,姜立新,董曼,潘博,席楠. 2015. 基于余震序列分布信息的地震极灾区快速判断方法研究[J]. 灾害学,30(1):8–15. doi: 10.3969/j.issn.1000-811X.2015.01.003 Yang T Q,Jiang L X,Dong M,Pan B,Xi N. 2015. Rapid determination method of extreme earthquake disaster area based on aftershock sequence spatial distribution[J]. Journal of Catastrophology,30(1):8–15 (in Chinese).
易桂喜,龙锋,梁明剑,赵敏,王思维,宫悦,乔慧珍,苏金荣. 2019. 2019年6月17日四川长宁MS 6.0地震序列震源机制解与发震构造分析[J]. 地球物理学报,62(9):3432–3447. doi: 10.6038/cjg2019N0297 Yi G X,Long F,Liang M J,Zhao M,Wang S W,Gong Y,Qiao H Z,Su J R. 2019. Focal mechanism solutions and seismogenic structure of the 17 June 2019 MS 6.0 Sichuan Changning earthquake sequence[J]. Chinese Journal of Geophysics,62(9):3432–3447 (in Chinese).
喻畑,赵亚敏,陆鸣. 2014. 芦山地震地震动上下盘效应研究[J]. 震灾防御技术,9(3):431–438. doi: 10.11899/zzfy20140309 Yu T,Zhao Y M,Lu M. 2014. Study of hanging-wall effect of fault in Lushan earthquake[J]. Technology for Earthquake Disaster Prevention,9(3):431–438 (in Chinese).
俞言祥,高孟潭. 2001. 台湾集集地震近场地震动的上盘效应[J]. 地震学报,24(6):615–621. doi: 10.3321/j.issn:0253-3782.2001.06.007 Yu Y X,Gao M T. 2001. Effects of the hanging wall and footwall on peak acceleration during the Chi-Chi earthquake,Taiwan[J]. Acta Seismologica Sinica,24(6):615–621 (in Chinese).
赵珠,张润生. 1987. 四川地区地壳上地幔速度结构的初步研究[J]. 地震学报,9(2):154–166. Zhao Z,Zhang R S. 1987. Primary study of crustal and upper mantle velocity structure of Sichuan Province[J]. Acta Seismologica Sinica,9(2):154–166 (in Chinese).
郑韵,姜立新,王辉山,王洪栋. 2018. 基于余震粒子群算法的极震区快速判定方法研究[J]. 地震,38(4):120–131. doi: 10.3969/j.issn.1000-3274.2018.04.011 Zheng Y,Jiang L X,Wang H S,Wang H D. 2018. Rapid determination method of magistoseismic area based on aftershock particle swarm algorithm[J]. Earthquake,38(4):120–131 (in Chinese).
邹立晔,黄志斌,周静,梁姗姗,赵博,杜广宝,刘敬光,陈宏峰. 2019. 2019年6月17日四川长宁MS6.0地震的快速测定与数据产品产出[J]. 中国地震,35(3):573–583. doi: 10.3969/j.issn.1001-4683.2019.03.016 Zou L Y,Huang Z B,Zhou J,Liang S S,Zhao B,Du G B,Liu J G,Chen H F. 2019. Quick determination and data products of the MS6.0 earthquake on June 17,2019 in Changning,Sichuan[J]. Earthquake Research in China,35(3):573–583 (in Chinese).
Kisslinger C,Jones L M. 1991. Properties of aftershock sequences in southern California[J]. J Geophys Res,96(B7):11947–11958. doi: 10.1029/91JB01200
Lefever D W. 1926. Measuring geographic concentration by means of the standard deviational ellipse[J]. Am J Soc,32(1):88–94. doi: 10.1086/214027
Mitchell A. 2005. The ESRI Guide to GIS Analysis, Volume 2: Spatial Measurement and Statistics[M]. California: ESRI Press: 49–50.
Richter C F. 1955. Foreshocks and aftershocks:In earthquakes in Kern County California during 1952[J]. Div Mines Bull,171:177–197.
Waldhauser F,Ellsworth W. 2000. A double-difference earthquake location algorithm:Method and application to the northern Hayward Fault,California[J]. Bull Seismol Soc Am,90(6):1353–1368. doi: 10.1785/0120000006
Wang D,Xie L L,Abrahamson N A,Li S Y. 2010. Comparison of strong ground motion from the Wenchuan,China,earthquake of 12 May 2008 with the Next Generation Attenuation(NGA)ground-motion models[J]. Bull Seismol Soc Am,100(5B):2381–2395. doi: 10.1785/0120090009
下载:
计量
- 文章访问数: 1045
- HTML全文浏览量: 554
- PDF下载量: 78
