四川断层活动性分析及汶川、芦山地震活动关联性研究
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摘要
基于龙门山、鲜水河、安宁河-则木河断裂带上跨断层水准资料,计算不同场地年均形变速率和断层垂直形变累积率,分析断层年变速率和Dc空间分布等值线变化,揭示汶川地震前后断层活动规律、区域应变、应力场的能力聚集程度,进而探讨汶川、芦山两次地震的关联性。结果显示:1)汶川地震的发生明显加剧了龙门山断裂带中南段的断层活动性,年均形变速率由震前<1mm/a,到震后最大达10.01mm/a;汶川地震的发生对安宁河-则木河断裂带上的汤家坪、西昌场地影响较大,年变速率显著增加,断层活动性得到加强;2)汶川地震发生前,龙门山断裂东北段存在Dc高值区,随后Dc值逐渐减小,汶川地震的发生存在一定的应力累积背景;汶川地震发生后明显改变了整个龙门山断裂带的Dc空间分布,加速形成围绕双河场地的Dc高值环绕区,而芦山地震的震中位置位于高值与低值交界区域,空间差异较为显著。
The paper considers the Wenchuan and Lushan earthquakes,which occurred in the Longmenshan fault zone.Based on the cross fault leveling data of Longmenshan,Xianshuihe and Anninghe-Zemuhe fault zones,the annual deformation rate of different sites and the accumulation rate of fault vertical deformation are calculated.The analyses of the annual deformation rate and the spatial distribution of Dccontour map changes reveal the fault activity law.We ascertain the regional strain and the stress field before and after the Wenchuan earthquake,then discuss the correlation of the two earthquakes.The results show:(1)The occurrence of the Wenchuan earthquake obviously increases the fault activity in the southern tip of the Longmenshan fault zone.The average annual rate of change before the earthquake is increased by <1 mm/a,increasing to a maximum of 10.01 mm/a after the earthquake.The occurrence of Wenchuan earthquake has great impact on Tangjiaping and Xichang sites on Anninghe-Zemuhe fault zone,where the annual rate of change increases,and the activity of the fault is strengthened.(2)Before the occurrence of the Wenchuan earthquake,the northeast section of Longmenshan fault shows a high Dcvalue area;afterward,it gradually reduces.The occurrence of Wenchuan earthquake presents a background of stress accumulation.The spatial distribution of Dcin the Longmeshan fault zone obviously changes after the Wenchuan earthquake,accelerating the formation of a high Dcvalue around the site of Shuanghe site.The Lushan earthquake epicenter is located in the high value and the low value region,with a significant spatial difference.
The paper considers the Wenchuan and Lushan earthquakes,which occurred in the Longmenshan fault zone.Based on the cross fault leveling data of Longmenshan,Xianshuihe and Anninghe-Zemuhe fault zones,the annual deformation rate of different sites and the accumulation rate of fault vertical deformation are calculated.The analyses of the annual deformation rate and the spatial distribution of Dccontour map changes reveal the fault activity law.We ascertain the regional strain and the stress field before and after the Wenchuan earthquake,then discuss the correlation of the two earthquakes.The results show:(1)The occurrence of the Wenchuan earthquake obviously increases the fault activity in the southern tip of the Longmenshan fault zone.The average annual rate of change before the earthquake is increased by <1 mm/a,increasing to a maximum of 10.01 mm/a after the earthquake.The occurrence of Wenchuan earthquake has great impact on Tangjiaping and Xichang sites on Anninghe-Zemuhe fault zone,where the annual rate of change increases,and the activity of the fault is strengthened.(2)Before the occurrence of the Wenchuan earthquake,the northeast section of Longmenshan fault shows a high Dcvalue area;afterward,it gradually reduces.The occurrence of Wenchuan earthquake presents a background of stress accumulation.The spatial distribution of Dcin the Longmeshan fault zone obviously changes after the Wenchuan earthquake,accelerating the formation of a high Dcvalue around the site of Shuanghe site.The Lushan earthquake epicenter is located in the high value and the low value region,with a significant spatial difference.
引文
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[6]张希,王双绪,张晓亮,等.昆仑山与汶川强烈地震对青藏块体东北缘地壳运动及应变积累的影响[J].地球学报,2010,31(1):32-42(Zhang Xi,Wang Shuangxu,Zhang Xiaoliang,et al.The Influence of the Kunlun Mountains and Wenchuan Strong Earthquakes on the Crustal Movement and Strain Accumulation in the Northeastern Margin of Qinghai-Xizang Block[J].Acta Geoscientica Sinica,2010,31(1):32-42)
[7]王永安,刘强,王世芹,等.云南地区大震前地倾斜趋势性异常的典型特征[J].地震研究,2003(S1):126-132(Wang Yongan,Liu Qiang,Wang Shiqin,et al.The Typical Characteristics of the Trend Anomaly of Tilting Deformation at the Fixed Observational Sites before the Occurrence of Strong Earthquakes in Yunnan[J].Journal of Seismological Research,2003(S1):126-132.
[8]陈兵,江在森,胡斌.断层形变趋势变化研究——垂直形变趋势累积率Dc值[J].地震地磁观测与研究,2000,21(1):50-55(Chen Bing,Jiang Zaisen,Hu Bin.Study of Trend Variation of Fault Deformation-Vertical Deformation Trend Accumulation Rate Dc[J].Seismological&Geomagnetic Observation&Research,2000,21(1):50-55)
[9]李媛,刘峡,刘希康,等.2016年门源MS6.4地震前祁连山周边断层活动分析[J].大地测量与地球动力学,2016(4):288-293(Li Yuan,Liu Xia,Liu Xikang,et al.Activity Analysis of Faults Around Qilianshan before the 2016 Menyuan MS6.4Earthquake[J].Journal of Geodesy and Geodynamics,2016(4):288-293)
[10]陈运泰,杨智娴,张勇,等.浅谈芦山地震[J].地震学报,2013,35(3):285-295(Chen Yuntai,Yang Zhixian,Zhang Yong,et al.A Brief Talk on the 20 April 2013 Lushan MW6.7Earthquake[J].Acta Seismologica Sinica,2013,35(3):285-295)
[11]徐锡伟,陈桂华,于贵华,等.芦山地震发震构造及其与汶川地震关系讨论[J].地学前缘,2013(3):11-20(Xu Xiwei,Chen Guihua,Yu Guihua,et al.Seismogenic Structure of Lushan Earthquake and Its Relationship with Wenchuan Earthquake[J].Earth Science Frontiers,2013(3):11-20)
[12]江在森,丁平,王双绪,等.中国西部大地形变监测与地震预报[M].北京:地震出版社,2001(Jiang Zaisen,Ding Ping,Wang Shuangxu,et al.The Geotectonic Deformation Monitoring and Earthquake Prediction in the West of China[M].Beijing:Seismological Press,2001)
[13]孙军,葛计划,曹志磊,等.跨断层水准数据处理方法在苏鲁皖地区的应用[J].防灾科技学院学报,2014(3):32-37(Sun Jun,Ge Jihua,Cao Zhilei,et al.The Application of the Cross Fault Leveling Data Processing Method in Jiangsu,Shandong,and Anhui Provinces[J].Journal of Institute of Disaster Prevention,2014(3):32-37)
[2]刘杰,易桂喜,张致伟,等.2013年4月20日四川芦山M7.0级地震介绍[J].地球物理学报,2013,56(4):1 404-1 407(Liu Jie,Yi Guixi,Zhang Zhiwei,et al.Introduction to the Lushan,Sichuan M7.0Earthquake on 20April 2013[J].Acta Geophysica Sinica,2013,56(4):1 404-1 407)
[3]单斌,熊熊,郑勇,等.2013年芦山地震导致的周边断层应力变化及其与2008年汶川地震的关系[J].中国科学:地球科学,2013,56(7):1 002-1 009(Shan Bin,Xiong Xiong,Zheng Yong,et al.Stress Changes on Major Faults Caused by 2013Lushan Earthquake and Its Relationship with 2008Wenchuan Earthquake[J].Science China Earth Sciences,2013,56(7):1 002-1 009
[4]Ekirby T C.Stress Changes from the 2008 Wenchuan Earthquake and Increased Hazard in the Sichuan Basin[J].Nature,2008,454(7 203):509-510
[5]单斌,熊熊,郑勇,等.2008年5月12日MW7.9汶川地震导致的周边断层应力变化[J].中国科学:地球科学,2009,52(5):537-545(Shan Bin,Xiong Xiong,Zheng Yong,et al.Stress Changes on Major Faults Caused by MW7.9Wenchuan Earthquake,May 12,2008[J].Science China Earth Sciences,2009,52(5):537-545)
[6]张希,王双绪,张晓亮,等.昆仑山与汶川强烈地震对青藏块体东北缘地壳运动及应变积累的影响[J].地球学报,2010,31(1):32-42(Zhang Xi,Wang Shuangxu,Zhang Xiaoliang,et al.The Influence of the Kunlun Mountains and Wenchuan Strong Earthquakes on the Crustal Movement and Strain Accumulation in the Northeastern Margin of Qinghai-Xizang Block[J].Acta Geoscientica Sinica,2010,31(1):32-42)
[7]王永安,刘强,王世芹,等.云南地区大震前地倾斜趋势性异常的典型特征[J].地震研究,2003(S1):126-132(Wang Yongan,Liu Qiang,Wang Shiqin,et al.The Typical Characteristics of the Trend Anomaly of Tilting Deformation at the Fixed Observational Sites before the Occurrence of Strong Earthquakes in Yunnan[J].Journal of Seismological Research,2003(S1):126-132.
[8]陈兵,江在森,胡斌.断层形变趋势变化研究——垂直形变趋势累积率Dc值[J].地震地磁观测与研究,2000,21(1):50-55(Chen Bing,Jiang Zaisen,Hu Bin.Study of Trend Variation of Fault Deformation-Vertical Deformation Trend Accumulation Rate Dc[J].Seismological&Geomagnetic Observation&Research,2000,21(1):50-55)
[9]李媛,刘峡,刘希康,等.2016年门源MS6.4地震前祁连山周边断层活动分析[J].大地测量与地球动力学,2016(4):288-293(Li Yuan,Liu Xia,Liu Xikang,et al.Activity Analysis of Faults Around Qilianshan before the 2016 Menyuan MS6.4Earthquake[J].Journal of Geodesy and Geodynamics,2016(4):288-293)
[10]陈运泰,杨智娴,张勇,等.浅谈芦山地震[J].地震学报,2013,35(3):285-295(Chen Yuntai,Yang Zhixian,Zhang Yong,et al.A Brief Talk on the 20 April 2013 Lushan MW6.7Earthquake[J].Acta Seismologica Sinica,2013,35(3):285-295)
[11]徐锡伟,陈桂华,于贵华,等.芦山地震发震构造及其与汶川地震关系讨论[J].地学前缘,2013(3):11-20(Xu Xiwei,Chen Guihua,Yu Guihua,et al.Seismogenic Structure of Lushan Earthquake and Its Relationship with Wenchuan Earthquake[J].Earth Science Frontiers,2013(3):11-20)
[12]江在森,丁平,王双绪,等.中国西部大地形变监测与地震预报[M].北京:地震出版社,2001(Jiang Zaisen,Ding Ping,Wang Shuangxu,et al.The Geotectonic Deformation Monitoring and Earthquake Prediction in the West of China[M].Beijing:Seismological Press,2001)
[13]孙军,葛计划,曹志磊,等.跨断层水准数据处理方法在苏鲁皖地区的应用[J].防灾科技学院学报,2014(3):32-37(Sun Jun,Ge Jihua,Cao Zhilei,et al.The Application of the Cross Fault Leveling Data Processing Method in Jiangsu,Shandong,and Anhui Provinces[J].Journal of Institute of Disaster Prevention,2014(3):32-37)