大姚、民乐-山丹地震前的中短期前兆
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摘要
利用川滇及青藏块体北缘地区上世纪 80年代至 2 0 0 3年的跨断层流动形变观测资料 ,借助应变强度比时序曲线 ,通过丽江Ms7.0、景泰Ms5 .9等震例研究 ,获取与 2 0 0 3年 7月大姚Ms6 .2、Ms6 .1地震和 10月民乐 山丹Ms6 .1地震孕育有关的中短期前兆异常。分析表明 :①大姚、民乐 山丹地震前 1年内异常场地数远超过场地总数的 1/ 3,相对近源区异常在发震地区占一半 ;②大姚Ms6 .2地震前半年内 ,盐源 丽江地块及其邻近区域以及北东向延伸的川滇交界地区异常明显增多 ,相对集中。 2 0 0 3年 7～ 9月大幅减弱 ;而鲜水河断裂、楚雄 通海断裂南段有所增强 ;③民乐 山丹震前十余天至数月内相对近源区及其邻近构造区域呈现异常相对分散 相对集中且局部增强 临震前减弱的时空演变特征。震后一个月内青藏块体北缘地区仍有近 1/ 3的场地呈现异常 (海原 六盘山断裂带尤为突出 )。
Using mobile observations of deformation of cross-faults from the 1980s to 2003 in Sichuan-Yunnan area and the northern margin of Qinghai-Tibet block, by means of the time-curve of strain intensity ratio and analyses the seismic examples such as the Lijiang %M%s7.0 and the Jingtai %M%s5.9,the medium and short-term of precursory anomalies related to the Daoyao Ms6.2,Ms6.1 and Minle-Shandan Ms6.1 earthquakes which took place respectively on July and October of 2003 are studied. It is shown that: ①The number of sites with anomaly for one year before the Daoyao and Minle-Shandan earthquakes was much more than 1/3 of total, and the number of sites with anomaly in the region nearby the epicenter was half of that in the area where the earthquakes took place. ②In six months,before Daoyao earthquake, Yanyuan-Lijiang block and its nearby, together with its expanding northeastward to the boundary between Sichuan and Yunnan,the precursory anomalies increased remarkably and concentrated relatiely. Furthermore, from July to September of 2003, the precursory anomalies became weak obviously in this region, but stronger in the Xianshuihe fault and the southern segment of Chuxiong-Tonghai fault. ③From dozen days to serveal months before the Minle-Shandan earthquake in the region near the epicenter the time-space evolution features of deformation anomalies manifest themselves from relatively sparse to relatively concentrated and anomalies with locally enhanced to decreased.In a month after the earthquake, nearly 1/3 of sites revealed abnormal deformation(especially Haiyuan-Liupanshan fracture belt).
Using mobile observations of deformation of cross-faults from the 1980s to 2003 in Sichuan-Yunnan area and the northern margin of Qinghai-Tibet block, by means of the time-curve of strain intensity ratio and analyses the seismic examples such as the Lijiang %M%s7.0 and the Jingtai %M%s5.9,the medium and short-term of precursory anomalies related to the Daoyao Ms6.2,Ms6.1 and Minle-Shandan Ms6.1 earthquakes which took place respectively on July and October of 2003 are studied. It is shown that: ①The number of sites with anomaly for one year before the Daoyao and Minle-Shandan earthquakes was much more than 1/3 of total, and the number of sites with anomaly in the region nearby the epicenter was half of that in the area where the earthquakes took place. ②In six months,before Daoyao earthquake, Yanyuan-Lijiang block and its nearby, together with its expanding northeastward to the boundary between Sichuan and Yunnan,the precursory anomalies increased remarkably and concentrated relatiely. Furthermore, from July to September of 2003, the precursory anomalies became weak obviously in this region, but stronger in the Xianshuihe fault and the southern segment of Chuxiong-Tonghai fault. ③From dozen days to serveal months before the Minle-Shandan earthquake in the region near the epicenter the time-space evolution features of deformation anomalies manifest themselves from relatively sparse to relatively concentrated and anomalies with locally enhanced to decreased.In a month after the earthquake, nearly 1/3 of sites revealed abnormal deformation(especially Haiyuan-Liupanshan fracture belt).
引文
1 陈兵,江在森,胡亚轩.祁连川滇复合菱形块体周边主要活动断裂带断层形变特征与机理[J].四川地震,1999(3):50～60.
1 ChenBing,JiangZaisenandHuYaxuan.FaultdeformationcharacteristicsandmechanismaboutthemainfracturebeltofthecompoundrhombusblockofQilianChuandian[J].EarthquakeResearchinSichuan,1999(3):50-60.(inChi nese)
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4 NiuAnfu,ZhangJingandGaoFuwang.Studyonthecon tinuouslyaccelerateddeformationandtherelationshipwithearthquakes[J].JournalofGeodesyandGeodynamics,2002,22(1):29-33.(inChinese)
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6 张希,江在森,陈文胜,等.我国西部近期应变强度比动态演化特征[J].地震研究,2001,24(2):115～120.
6 ZhangXi,JiangZaisen,ChenWensheng,etal.DynamicevolutioncharacteristicsofstrainstrengthratiointheWestofChina[J].JournalofSeismologicalResearch,2001,24(2):115-120.(inChinese)
7 张希,江在森,王双绪,等.断层形变的应变强度比动态图像与震例综合研究[J].地壳形变与地震,2001,21(2):37～42.
7 ZhangXi,JiangZaisen,WangShuangxu,etal.Comprehen sivestudyondynamicpatternsofstrainstrengthratiooffaultdeformationandseismicexamples[J].CrustalDefor mationandEarthquake,2001,21(2):37-42.(inChinese)
8 张希,江在森,王琪,等.川滇地区地壳水平运动特征与强震关系研究[J].大地测量与地球动力学,2003,23(3):35～41.
8 ZhangXi,JiangZaisen,WangQi,etal.Recentcrustalmo tionfeaturesofSichuanYunnanandtheirrelationshiptostrongearthquakes[J].JournalofGeodesyandGeodynam ics,2003,23(3):35-41.(inChinese)
9 张希,江在森,王琪,等.1999～2001年青藏块体东北缘地壳水平运动的非震反位错模型及变形分析[J].地震学报,2003,25(4):374～381.
9 ZhangXi,JiangZaisen,WangQi,etal.Aseismicnegativedislocationmodelanddeformationanalysisofcrustalhorizon talmovementduring1999-2001inthenortheastmarginofQinghaiTibetblock[J].ActaSeismologicaSinica,2003,25(4):374-381.(inChinese)
10 张希,王双绪,崔笃信,等.民乐山丹地震的区域构造变形背景与中短期前兆[J].中国地震,2004,20(3).
10 ZhangXi,WangShuangxu,CuiDuxin,etal.Regionaltec tonicbackgroundandmedium short termprecursorsofMinleShandanearthquakes[J].EarthquakeResearchinChina,2004,20(3).(inChinese)
1 ChenBing,JiangZaisenandHuYaxuan.FaultdeformationcharacteristicsandmechanismaboutthemainfracturebeltofthecompoundrhombusblockofQilianChuandian[J].EarthquakeResearchinSichuan,1999(3):50-60.(inChi nese)
2 王双绪,江在森,陈文胜,等.景泰5.9级地震的断层形变异常及中短期预报[J].地震学报,2001,23(2):151～158.
2 WangShuangxu,JiangZaisen,ChenWensheng,etal.Faultdeformationanomalyandmediumandshort term predictionofJingtaiMs5.9earthquake[J].ActaSeismologicaSinica,2001,23(2):151-158.(inChinese)
3 王双绪,江在森,张希,等.青藏块体东北缘现今构造形变与蕴震特征[J].地震学报,2002,24(1):27～34.
3 WangShuangxu,JiangZaisen,ZhangXi,etal.Currenttec tonicdeformationandseismogeniccharacteristicsalongthenortheastmarginofQinghaiTibetblock[J].ActaSeismolog icaSinica,2002,24(1):27-34.(inChinese)
4 牛安福,张晶,高福旺.地壳持续加速变形与地震关系的研究[J].大地测量与地球动力学,2002,22(1):29～33.
4 NiuAnfu,ZhangJingandGaoFuwang.Studyonthecon tinuouslyaccelerateddeformationandtherelationshipwithearthquakes[J].JournalofGeodesyandGeodynamics,2002,22(1):29-33.(inChinese)
5 张希,江在森,陈文胜,等.川滇地区应变强度比动态图像分析[J],高原地震,1999,11(3):15～21.
5 ZhangXi,JiangZaisen,ChenWensheng,etal.AnalysisofdynamicpicturesofstrainstrengthratioinSichuanYunnanarea[J].PlateauEarthquakes,1999,11(3):15-21.(inChinese)
6 张希,江在森,陈文胜,等.我国西部近期应变强度比动态演化特征[J].地震研究,2001,24(2):115～120.
6 ZhangXi,JiangZaisen,ChenWensheng,etal.DynamicevolutioncharacteristicsofstrainstrengthratiointheWestofChina[J].JournalofSeismologicalResearch,2001,24(2):115-120.(inChinese)
7 张希,江在森,王双绪,等.断层形变的应变强度比动态图像与震例综合研究[J].地壳形变与地震,2001,21(2):37～42.
7 ZhangXi,JiangZaisen,WangShuangxu,etal.Comprehen sivestudyondynamicpatternsofstrainstrengthratiooffaultdeformationandseismicexamples[J].CrustalDefor mationandEarthquake,2001,21(2):37-42.(inChinese)
8 张希,江在森,王琪,等.川滇地区地壳水平运动特征与强震关系研究[J].大地测量与地球动力学,2003,23(3):35～41.
8 ZhangXi,JiangZaisen,WangQi,etal.Recentcrustalmo tionfeaturesofSichuanYunnanandtheirrelationshiptostrongearthquakes[J].JournalofGeodesyandGeodynam ics,2003,23(3):35-41.(inChinese)
9 张希,江在森,王琪,等.1999～2001年青藏块体东北缘地壳水平运动的非震反位错模型及变形分析[J].地震学报,2003,25(4):374～381.
9 ZhangXi,JiangZaisen,WangQi,etal.Aseismicnegativedislocationmodelanddeformationanalysisofcrustalhorizon talmovementduring1999-2001inthenortheastmarginofQinghaiTibetblock[J].ActaSeismologicaSinica,2003,25(4):374-381.(inChinese)
10 张希,王双绪,崔笃信,等.民乐山丹地震的区域构造变形背景与中短期前兆[J].中国地震,2004,20(3).
10 ZhangXi,WangShuangxu,CuiDuxin,etal.Regionaltec tonicbackgroundandmedium short termprecursorsofMinleShandanearthquakes[J].EarthquakeResearchinChina,2004,20(3).(inChinese)
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