2003年2月24日新疆巴楚-伽师6.8级地震发震构造
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摘要
2003年2月24日发生在新疆塔里木盆地的巴楚-伽师6.8级地震可能是1997—1998年伽师强震群的继续,但其震源机制解、破裂过程与1997—1998年的强震群有一定的差别。从地震重新定位的结果看,巴楚-伽师6.8级地震与塔西南坳陷东侧麦盖提斜坡带上发育的一组NWW向隐伏逆断层有关,地震宏观考察①所发现的与构造变形有关的地裂缝也与这一隐伏断层带的位置相吻合,等震线形态与隐伏断层带的走向一致,极震区的形态与断层的破裂方向基本一致。这些均表明这次地震是盆地内一条近EW向北倾逆断层自NW向SE由深至浅破裂的结果。
The M_ S 6.8 Bachu-Jiashi earthquake of Feb.24, 2003 occurred in the western Tarim Basin and is possibly the continuation of the Jiashi strong earthquake swarms in 1997—1998. However, its focal mechanism and rupture process are different from that of the Jiashi strong earthquake swarms, according to our preliminary study on its seismic tectonics with geomorphologic information from satellite images, the deep structures from the petroleum seismic exploration, the macro damage and isoseismic features from field investigation, the relocation of the epicenters of the aftershocks, and the regional seismic tectonics from both deep and surface tectonics. The occurrence of the M_ S 6.8 Bachu-Jiashi earthquake is closely related with the revealed reverse fault on the Maigaiti slope belt between the Bachu uplift and Kashi depression in western Tarim Basin. The sites of the ground fissures found in the field fit with the revealed reverse fault. Isoseismal features are also corresponding to the rupture direction of the fault. These evidences indicate that the M_ S 6.8 Bachu-Jiashi earthquake is the result of the southward rupturing from deep to shallow along a north-dipping reverse fault in Tarim Basin. This reverse fault is possibly the result of the propagation of the thrust fault-fold system named Kalpintag thrust belt in the front of Tianshan.
The M_ S 6.8 Bachu-Jiashi earthquake of Feb.24, 2003 occurred in the western Tarim Basin and is possibly the continuation of the Jiashi strong earthquake swarms in 1997—1998. However, its focal mechanism and rupture process are different from that of the Jiashi strong earthquake swarms, according to our preliminary study on its seismic tectonics with geomorphologic information from satellite images, the deep structures from the petroleum seismic exploration, the macro damage and isoseismic features from field investigation, the relocation of the epicenters of the aftershocks, and the regional seismic tectonics from both deep and surface tectonics. The occurrence of the M_ S 6.8 Bachu-Jiashi earthquake is closely related with the revealed reverse fault on the Maigaiti slope belt between the Bachu uplift and Kashi depression in western Tarim Basin. The sites of the ground fissures found in the field fit with the revealed reverse fault. Isoseismal features are also corresponding to the rupture direction of the fault. These evidences indicate that the M_ S 6.8 Bachu-Jiashi earthquake is the result of the southward rupturing from deep to shallow along a north-dipping reverse fault in Tarim Basin. This reverse fault is possibly the result of the propagation of the thrust fault-fold system named Kalpintag thrust belt in the front of Tianshan.
引文
[1]巴楚-伽师地震现场应急工作队,2003,新疆巴楚-伽师6.8级地震现场工作报告。
[1]同205页[1]。
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王卫民,李丽,赵连锋,等.2005.2003年2月24日新疆伽师MS6.5级地震震源破裂过程研究[J].地球物理学报,48(2):343—351.WANGWei-min,LILi,ZHAOLian-feng,etal.2005.RuptureprocessofJiashi,Xinjiangearthquake(MS6.5)ofFeb.24,2003[J].ChineseJournalofGeophysics,48(2):343—351(inChinese).
赵翠萍,夏爱国.2003.新疆巴楚-伽师6.8级地震序列震源特征的初步研究[J].内陆地震,17(2):182—189.ZHAOCui-ping,XIAAi-guo.2003.PrimarystudyonthesourcefeatureofBachu-JiashiMS6.8earthquakeseries[J].InlandEarthquake,17(2):182—189(inChinese).
周仕勇,许忠淮.2000.由震源谱推断1997年新疆伽强震群破裂特征[J].地震学报,22(2):113—124.ZHOUShi-yong,XUZhong-huai.2000.Fracturecharacteristicsofthe1997Jiashi,Xinjiang,China,earthquakeswarminferredfromsourcespectrum[J].ActaSeismologicaSinica,22(2):113—124(inChinese).
周仕勇,徐忠淮,陈晓非.2001.1997年伽师强震群生成机理研究[J].自然科学进展,11(9):999—1004.ZHOUShi-yong,XUZhong-huai,CHENXiao-fei.2001.Studyonseismogenicprocessofthe1997Jiashistrongearth-quakeswarms[J].ProgressinNaturalScience,11(9):999—1004(inChinese).
[1]同205页[1]。
高国英,聂晓红,夏爱国.2004.2003年伽师6.8级地震序列特征和震源机制的初步研究[J].中国地震,20(2):179—186.GAOGuo-ying,NIEXiao-hong,XIAAi-guo.2004.PreliminarystudyoncharacteristicsoftheJiashiearthquakese-quencewithMS6.8anditsFocalmechanismsolutionsin2003[J].EarthquakeResearchinChina,20(2):179—186(inChinese).
郭飙,刘启元,陈久辉,等.2002.新疆伽师强震区余震序列的地震台阵定位[J].地震地质,24(2):199—207.GUOBiao,LIUQi-yuan,CHENJiu-hui,etal.2002.Relocationofearthquakesequencesusingjointhypocenterdetermi-nationmethod:portableseismicarraystudyinJiashiregion,Xinjiang[J].SeismologyandGeology,24(2):199—207(inChinese).
李松林,张先康,MooneyWD,等.2002.伽师地震区地壳细结构及发震断层的初步研究[J].地球物理学报,45(1):76—82.LISong-lin,ZHANGXian-kang,MooneyWD,etal.2002.ApreliminarystudyonfinestructuresofJiashiearthquakeregionandearthquakegeneratingfault[J].ChineseJournalofGeophysics,45(1):76—82(inChinese).
苏迺秦.2003.新疆伽师强震群强震主破裂面走向初探[J].西北地震学报,25(3):269—274.SUNai-qin.2003.PreliminarystudyonstrikeofmainrupturesurfaceofJiashistrongearthquakeswarm[J].NortwesternSeismologicalJournal,25(3):269—274(inChinese).
王卫民,李丽,赵连锋,等.2005.2003年2月24日新疆伽师MS6.5级地震震源破裂过程研究[J].地球物理学报,48(2):343—351.WANGWei-min,LILi,ZHAOLian-feng,etal.2005.RuptureprocessofJiashi,Xinjiangearthquake(MS6.5)ofFeb.24,2003[J].ChineseJournalofGeophysics,48(2):343—351(inChinese).
赵翠萍,夏爱国.2003.新疆巴楚-伽师6.8级地震序列震源特征的初步研究[J].内陆地震,17(2):182—189.ZHAOCui-ping,XIAAi-guo.2003.PrimarystudyonthesourcefeatureofBachu-JiashiMS6.8earthquakeseries[J].InlandEarthquake,17(2):182—189(inChinese).
周仕勇,许忠淮.2000.由震源谱推断1997年新疆伽强震群破裂特征[J].地震学报,22(2):113—124.ZHOUShi-yong,XUZhong-huai.2000.Fracturecharacteristicsofthe1997Jiashi,Xinjiang,China,earthquakeswarminferredfromsourcespectrum[J].ActaSeismologicaSinica,22(2):113—124(inChinese).
周仕勇,徐忠淮,陈晓非.2001.1997年伽师强震群生成机理研究[J].自然科学进展,11(9):999—1004.ZHOUShi-yong,XUZhong-huai,CHENXiao-fei.2001.Studyonseismogenicprocessofthe1997Jiashistrongearth-quakeswarms[J].ProgressinNaturalScience,11(9):999—1004(inChinese).
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