2009年姚安Ms6.0地震重力场前兆变化机理
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摘要
利用2009年姚安Ms6.0地震前滇西实验场流动重力网2005—2009年9期复测数据,给出了区域重力场差分和累积动态变化图像。分析研究表明:1)重力场动态演化图像大体反映出震前地壳物质运动状态,累积动态变化更能反映区域构造运动与断裂构造作用,差分动态变化有利于突出短期局部效应;2)姚安地震显著重力"前兆"标志为:震前约2年穿过震中的近南北向正负过渡重力梯级带和约半年的以震中区为中心重力场变化呈现局部相对上升与下降的对称四象限分布;3)震中西部震前约3年持续的正重力变化应有利于震源能量的积累;4)震中区相对变化四象限分布图像反映出孕震体先存剪应力,为此提出了"闭锁剪力"前兆模式。
From the repeted gravimetry data of Dianxi Experimental Field from 2005 to 2009,local differential and cumulate gravity change pictures have been obtained.The study results from the data are as follows.1)The dynamic evolvement pictures of gravity field can generally reflect the movement state of the crustal substance before earthquake.Short-term local effect is obviously reflected by the differential dynamic change,while local tectonic movement and fault structure effect by the cumulate dynamic change.2)A positive and negative transitional gravity gradient zone across the epicenter along almost north-south direction appeared two years before the earthquake,and a symmetrical four-quadrant distribution of the gravity change appeared too around the epicenter half year before the earthquake.They were the prominent gravity precursor marks of the Yaoan earthquake.3)Durative positive gravity change appeared in the west to the epicenter three years before the earthquake.It was helpfull for energy accumulation.4)The relatively high-low four-quadrant distribution picture may reflect that there exist a shearing stress.So we put forward a 'lock in shearing force mode' for the precursor model.
From the repeted gravimetry data of Dianxi Experimental Field from 2005 to 2009,local differential and cumulate gravity change pictures have been obtained.The study results from the data are as follows.1)The dynamic evolvement pictures of gravity field can generally reflect the movement state of the crustal substance before earthquake.Short-term local effect is obviously reflected by the differential dynamic change,while local tectonic movement and fault structure effect by the cumulate dynamic change.2)A positive and negative transitional gravity gradient zone across the epicenter along almost north-south direction appeared two years before the earthquake,and a symmetrical four-quadrant distribution of the gravity change appeared too around the epicenter half year before the earthquake.They were the prominent gravity precursor marks of the Yaoan earthquake.3)Durative positive gravity change appeared in the west to the epicenter three years before the earthquake.It was helpfull for energy accumulation.4)The relatively high-low four-quadrant distribution picture may reflect that there exist a shearing stress.So we put forward a 'lock in shearing force mode' for the precursor model.
引文
1贾民育,邢灿飞,孙少安.滇西重力变化的二维图象及其与5级(Ms)以上地震的关系[J].地壳形变与地震,1995,(3),9-19.(Jia Minyu,Xing Canfei and Sun Sha-oan.Two-dimension pictures of gravity change in westernYunnan and their relations to the earthquakesMs>5.0[J].Crustal Deformation and Earthquake,1995,(3),9-19)
2吴国华,罗增雄,赖群.丽江7 0级地震前后滇西实验场的重力异常变化特征[J].地震研究,1997,20(1):101-107.(Wu Guohua,Luo Zengxiong and Lai Qun.The varia-tion characteristics of gravity anomaly in the earthquake pre-diction test site in western Yunnan before and after theM7.0Lijiang earthquake[J].Journal of Seismological Research.1997,20(1):101-107)
3孙少安,项爱民,李辉.滇西和北京区域重力场演化及其与地震的关系的探讨[J].地震,1999,19(1):97-106.(Sun Shaoan,Xiang Aimin and Li Hui.Research on evolu-tion of western Yunnan and Beijing regional gravity fields andtheir relationship with earthquake[J].Earthquake,1999,19(1):97-106)
4李辉,等.滇西地区重力场动态变化计算[J].地壳形变与地震,2000,(1),60-66.(Li Hui,et al.Computation of dy-namic gravity changes in the western area of Yunnan prov-ince[J].Crustal Deformation and Earthquake,2000,(1):60-66)
5申重阳,李辉,付广裕.丽江7.0级地震重力前兆模式研究[J].地震学报,2003,25(2):163-171.(Shen Chongy-ang,Li Hui and Fu Guangyu.Study on a gravity precursormode of theMs7.0 Lijiang earthquake[J].Acta Seismologi-cal Sinica,2003,16(2):175-184)
6孙少安,申重阳,项爱民.红河断裂带北段现今活动的重力效应[J].大地测量与地球动力学,2009,(3):1-5.(Sun Shaoan,Shen Chongyang and Xiang Aiming.Gravityeffect from present activity of northern segment of Red Riverfault zone[J].Journal of Geodesy andZK(Geodynamics,2009,(3):1-5)
7祝意青,郭树松,刘芳.攀枝花6.1、姚安6.0级地震前后区域重力场变化[J].大地测量与地球动力学,2010,(4):8-10.(Zhu Yiqing,Guo Shusong and Liu Fang.Var-iation of gravity field before and after PanzhihuaMs6.1 andYaoanMs6.0 earthquake[J].Journal of Geodesy and Geo-dynamics,2010,(4):8-10)
8李辉,等.中国大陆近期重力场动态图像[J].大地测量与地球动力学,2009,(3):1-10.(Li Hui,et al.Dynamicgravity change in recent years in China continent[J].Jour-nal of Geodesy and Geodynamics,2009,(3):1-10)
9中国岩石圈动力学图集编委会,中国岩石圈动力学地图集[M].北京:中国地图出版社,1989.(China lithosphereDynamic Atlas Compilation Committee.China ithosphere dy-namic atlas[M].Beijing:SinoMaps Press,1989)
10应绍奋,等.中国大陆垂直向现代地壳运动基本特征[J].中国地震,1988,4(4):1-8.(Ying Shaofen,etal.Basic characteristics of recent vertical crustal movementof China mainland[J].Earthquake Research in China,1988,4(4):1-8)
11于建民,丁平,江在森.滇西地区近期垂直形变场分析[J].地壳形变与地震,1987,(1):29-34.(Yu Jianmin,Ding Ping and Jiang Zaisen.Analysis of recent vertical de-formation field in westren Yunnan province[J].CrustalDeformation and Earthquake,1987,(1):29-34)
12张四新,张晓亮,程宏斌.滇西地区现今垂直形变演化特征[J].地震研究,2005,28(3):268-273.(ZhangSixin,Zhang Xiaoliang and Cheng Hongbin.Current fea-tures of vertical crust deformation in west Yunnan[J].Journal of Seismological Research,2005,28(3):268-273)
13 Okubo S.Gravity and potential changes due to shear andtensile faults in a half-space[J].J.Geophys.Res.,1992,97:7 137-7 144.
14谈洪波,申重阳,李辉.断层位错引起的重力变化特征研究[J].大地测量与地球动力学,2008,(4):54-62.(Tan Hongbo,Shen Chongyang and Li Hui.Characteristicsof surface gravity changes caused by a fault or faults dislo-cation[J].Journal of Geodesy and Geodynamics,2008,(4):54-62)
15申重阳,等.重力场动态变化与汶川Ms8.0地震孕育过程[J].地球物理学报,2009,52(10):2 547-2 557.(Shen Chongyang,et al.Dynamic variations of gravity andthe preperation process of the WenchuanMs8.0 earthquake[J].Chinese J.Geophys.,2009,52(10):2 547-2 557)
16申重阳,等.2008年于田Ms7.3地震前重力场动态变化特征分析[J].大地测量与地球动力学,2010,(4):1-6.(Shen Chongyang,et al.Characterstic analysis of dy-namic gravity change before YutianMs7.3 earthquake,2008[J].Journal of Geodesy and Geodynamics,2010,(4):1-6)
①中国地震信息网,2009(http://www.csi.ac.cn/manage/html/40288611c5c2ba0111c5c558b00001/_content/09_07/23/1248335284302.html)
2吴国华,罗增雄,赖群.丽江7 0级地震前后滇西实验场的重力异常变化特征[J].地震研究,1997,20(1):101-107.(Wu Guohua,Luo Zengxiong and Lai Qun.The varia-tion characteristics of gravity anomaly in the earthquake pre-diction test site in western Yunnan before and after theM7.0Lijiang earthquake[J].Journal of Seismological Research.1997,20(1):101-107)
3孙少安,项爱民,李辉.滇西和北京区域重力场演化及其与地震的关系的探讨[J].地震,1999,19(1):97-106.(Sun Shaoan,Xiang Aimin and Li Hui.Research on evolu-tion of western Yunnan and Beijing regional gravity fields andtheir relationship with earthquake[J].Earthquake,1999,19(1):97-106)
4李辉,等.滇西地区重力场动态变化计算[J].地壳形变与地震,2000,(1),60-66.(Li Hui,et al.Computation of dy-namic gravity changes in the western area of Yunnan prov-ince[J].Crustal Deformation and Earthquake,2000,(1):60-66)
5申重阳,李辉,付广裕.丽江7.0级地震重力前兆模式研究[J].地震学报,2003,25(2):163-171.(Shen Chongy-ang,Li Hui and Fu Guangyu.Study on a gravity precursormode of theMs7.0 Lijiang earthquake[J].Acta Seismologi-cal Sinica,2003,16(2):175-184)
6孙少安,申重阳,项爱民.红河断裂带北段现今活动的重力效应[J].大地测量与地球动力学,2009,(3):1-5.(Sun Shaoan,Shen Chongyang and Xiang Aiming.Gravityeffect from present activity of northern segment of Red Riverfault zone[J].Journal of Geodesy andZK(Geodynamics,2009,(3):1-5)
7祝意青,郭树松,刘芳.攀枝花6.1、姚安6.0级地震前后区域重力场变化[J].大地测量与地球动力学,2010,(4):8-10.(Zhu Yiqing,Guo Shusong and Liu Fang.Var-iation of gravity field before and after PanzhihuaMs6.1 andYaoanMs6.0 earthquake[J].Journal of Geodesy and Geo-dynamics,2010,(4):8-10)
8李辉,等.中国大陆近期重力场动态图像[J].大地测量与地球动力学,2009,(3):1-10.(Li Hui,et al.Dynamicgravity change in recent years in China continent[J].Jour-nal of Geodesy and Geodynamics,2009,(3):1-10)
9中国岩石圈动力学图集编委会,中国岩石圈动力学地图集[M].北京:中国地图出版社,1989.(China lithosphereDynamic Atlas Compilation Committee.China ithosphere dy-namic atlas[M].Beijing:SinoMaps Press,1989)
10应绍奋,等.中国大陆垂直向现代地壳运动基本特征[J].中国地震,1988,4(4):1-8.(Ying Shaofen,etal.Basic characteristics of recent vertical crustal movementof China mainland[J].Earthquake Research in China,1988,4(4):1-8)
11于建民,丁平,江在森.滇西地区近期垂直形变场分析[J].地壳形变与地震,1987,(1):29-34.(Yu Jianmin,Ding Ping and Jiang Zaisen.Analysis of recent vertical de-formation field in westren Yunnan province[J].CrustalDeformation and Earthquake,1987,(1):29-34)
12张四新,张晓亮,程宏斌.滇西地区现今垂直形变演化特征[J].地震研究,2005,28(3):268-273.(ZhangSixin,Zhang Xiaoliang and Cheng Hongbin.Current fea-tures of vertical crust deformation in west Yunnan[J].Journal of Seismological Research,2005,28(3):268-273)
13 Okubo S.Gravity and potential changes due to shear andtensile faults in a half-space[J].J.Geophys.Res.,1992,97:7 137-7 144.
14谈洪波,申重阳,李辉.断层位错引起的重力变化特征研究[J].大地测量与地球动力学,2008,(4):54-62.(Tan Hongbo,Shen Chongyang and Li Hui.Characteristicsof surface gravity changes caused by a fault or faults dislo-cation[J].Journal of Geodesy and Geodynamics,2008,(4):54-62)
15申重阳,等.重力场动态变化与汶川Ms8.0地震孕育过程[J].地球物理学报,2009,52(10):2 547-2 557.(Shen Chongyang,et al.Dynamic variations of gravity andthe preperation process of the WenchuanMs8.0 earthquake[J].Chinese J.Geophys.,2009,52(10):2 547-2 557)
16申重阳,等.2008年于田Ms7.3地震前重力场动态变化特征分析[J].大地测量与地球动力学,2010,(4):1-6.(Shen Chongyang,et al.Characterstic analysis of dy-namic gravity change before YutianMs7.3 earthquake,2008[J].Journal of Geodesy and Geodynamics,2010,(4):1-6)
①中国地震信息网,2009(http://www.csi.ac.cn/manage/html/40288611c5c2ba0111c5c558b00001/_content/09_07/23/1248335284302.html)
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