利用远震接收函数反演陕西地震台站下方的地壳厚度
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摘要
文中利用陕西数字地震遥测台网14个遥测子台记录的远震波形资料,用频率域反褶积方法提取接收函数,由H-Kappa叠加方法反演得到各台站下方的地壳厚度和泊松比。在此基础上结合相关地震构造文献,对陕西地区的地壳特征进行了分析,并讨论了陕西地震活动与地壳结构、地质构造之间的关系。研究结果表明:1)陕西地区的地壳总体趋势是东薄西厚,陕西南部和北部地区地壳较厚(≥40km),位于陕西中部的渭河盆地地壳较薄(34～40km);14个台站中,渭河盆地东部与山西交界的华阴台下方地壳厚度最薄(34km),而盆地西北端的陇县台位于六盘山余脉上,地壳厚度最厚(48km)。2)陕西地区泊松比值总体变化不大(0.24～0.29),可能表明这一地区的岩石组成以中度组分为主;以渭河盆地为界,向北靠近地台一侧泊松比值相对较高,向南靠近秦岭山脉一侧则比值相对较低。3)地震活动与地质构造之间存在内在的联系。渭河盆地处于几个构造体系的复合部位,属于强地震的多发区;陕西南部地区的地震活动相对较弱,主要发生在汉中盆地和安康盆地,受陕南几条主要断裂控制;陕西北部地区地质构造相对稳定,地震活动最弱。泊松比反映了地球内部的物质构成,分析认为其与地震活动存在一定的关系,即泊松比较高区域的地震活动性要高于较低的区域。
In this paper,we calculate receiver functions of body wave under the 14 stations in Shaanxi Province from 3-component digital waveform data of teleseismic earthquake events and obtain the thickness and Poisson ratio in crust of this area through H-kappa stacking.Through analysing the characteristics of crustal structure in Shaanxi Province,we discuss the relationship between seismic activity,crustal structure and geological structure in Shaanxi Province.The results show that(1)Crustal thickness in western Shaanxi is thicker than that in the east.Crustal thickness in the south and north of Shaanxi(≥40km)is larger than that in Weihe Basin,middle Shaanxi(about 34～40km).Among 14 stations,the crust beneath Huayin station is the thinnest(34km),which locates on the boundary between eastern Weihe Basin and Shanxi Province,and the biggest thickness(48km)appears beneath Longxian station at the northwestern end of Weihe Basin.(2)Poisson ratio in Shaanxi Province is about 0.24～0.29,which may be related to rock compositions.Poisson ratio in the north of Weihe Basin has higher values than those in the south.(3)There exist some relations between seismic activity and geological structure.The Weihe Basin with frequent earthquakes locates in a compound position of several tectonic systems.The Hanzhong Basin and Ankang Basin in the south of Shaanxi are controlled by several major faults,where the seismicity is relatively low.Seismic activity in northern Shaanxi is the lowest because of stable geological structure.Poisson ratio reflects material composition of earth interior.Our analysis suggests that seismic activity in the region with high Poisson ratio is higher than that with low Poisson ratio.
In this paper,we calculate receiver functions of body wave under the 14 stations in Shaanxi Province from 3-component digital waveform data of teleseismic earthquake events and obtain the thickness and Poisson ratio in crust of this area through H-kappa stacking.Through analysing the characteristics of crustal structure in Shaanxi Province,we discuss the relationship between seismic activity,crustal structure and geological structure in Shaanxi Province.The results show that(1)Crustal thickness in western Shaanxi is thicker than that in the east.Crustal thickness in the south and north of Shaanxi(≥40km)is larger than that in Weihe Basin,middle Shaanxi(about 34～40km).Among 14 stations,the crust beneath Huayin station is the thinnest(34km),which locates on the boundary between eastern Weihe Basin and Shanxi Province,and the biggest thickness(48km)appears beneath Longxian station at the northwestern end of Weihe Basin.(2)Poisson ratio in Shaanxi Province is about 0.24～0.29,which may be related to rock compositions.Poisson ratio in the north of Weihe Basin has higher values than those in the south.(3)There exist some relations between seismic activity and geological structure.The Weihe Basin with frequent earthquakes locates in a compound position of several tectonic systems.The Hanzhong Basin and Ankang Basin in the south of Shaanxi are controlled by several major faults,where the seismicity is relatively low.Seismic activity in northern Shaanxi is the lowest because of stable geological structure.Poisson ratio reflects material composition of earth interior.Our analysis suggests that seismic activity in the region with high Poisson ratio is higher than that with low Poisson ratio.
引文
安张辉,周民都,吴庆举,等.2004.接收函数方法研究进展[J].西北地震学报,26(4):362—364.AN Zhang-hui,ZHOU Min-dou,WU Qing-ju,et al.2004.New progress in research of receiver function method[J].Northwestern Seismological Journal,26(4):362—364(in Chinese).
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贺传松,王椿镛,吴庆举.2003.接收函数方法及其新的进展[J].地球物理学进展,18(2):224—228.HE Chuan-song,WANG Chun-yong,WU Qing-ju.2003.The receiver function method and its newprogress[J].Pro-gress in Geophysics,18(2):224—228(in Chinese).
姜家兰,黄长林.1986.陕西地区地壳厚度初探[J].西北地震学报,8(4):43—51.JIANG Jia-lan,HUANG Chang-lin.1986.A preliminary study on the crustal thickness in Shaanxi region[J].North-western Seismological Journal,8(4):43—51(in Chinese).
孔繁宗.1991.陕西新构造活动概要[J].中国区域地质,10(1):10—16.KONG Fan-zong.1991.Abrief account of the neotectonic activity in Shaanxi[J].Regional Geology of China,10(1):10—16(in Chinese).
李华,王良书,李成,等.2008.大别造山带西段宽频带数字地震台阵观测与地壳上地幔结构[J].中国科学(D辑),38(7):862—871.LI Hua,WANG Liang-shu,LI Cheng,et al.2008.Structure of the crust and uppermost mantle from broadband seismicarray in the western Dabie Mountains,east central China[J].Science in China(Ser D),38(7):862—871(inChinese).
李永华,吴庆举,田小波,等.2009.用接收函数方法研究云南及其邻区地壳上地幔结构[J].地球物理学报,52(1):67—80.LI Yong-hua,WU Qing-ju,TIAN Xiao-bo,et al.2009.Crustal structure in the Yunnan region determined by modelingreceiver functions[J].Chinese Journal of Geophysics,52(1):67—80(in Chinese).
楼海,王椿镛,吕智勇,等.2008.2008年汶川MS8.0级地震的深部构造环境:远震P波接收函数和布格重力异常的联合解释[J].中国科学(D辑),38(10):1207—1220.LOU Hai,WANG Chun-yong,L Zhi-yong,et al.2008.Deep tectonic setting of the2008WenchuanMS8.0earth-quake in southwestern China-Joint analysis of teleseismic P-wave receiver functions and Bouguer gravity anomalies[J].Science in China(Ser D),38(10):1207—1220(in Chinese).
陕西省地震局.2005.陕西省地震监测志[M].北京:地震出版社.Earthquake Administration of Shaanxi Province.2005.Seismic Monitoring Records of Shaanxi Province[M].Seismo-logical Press,Beijing(in Chinese).
宋立胜.1989.陕西省志:地震志[M].北京:地震出版社.SONG Li-sheng.1989.Shaanxi Provincial Annals:Earthquake[M].Seismological Press,Beijing(in Chinese).
田宝峰,李娟,王卫民,等.2008.华北太行山区地壳各向异性的接收函数证据[J].地球物理学报,51(5):1459—1467.TIAN Bao-feng,LI Juan,WANG Wei-min,et al.2008.Crust anisotropy of Taihangshan mountain range in North Chinainferred from receiver functions[J].Chinese Journal of Geophysics,51(5):1459—1467(in Chinese).
王椿镛,楼海,吕智勇,等.2008.青藏高原东部地壳上地幔S波速度结构:下地壳流的深部环境[J].中国科学(D辑),38(1):22—32.WANG Chun-yong,LOU Hai,L Zhi-yong,et al.2008.S-wave crustal and upper mantle s velocity structure in theeastern Tibetan Plateau-deep environment of lower crustal flow[J].Science in China(Ser D),38(1):22—32(in Chinese).
王小平,宋秀青,秦浩文.2005.接收函数方法应用的现状及其发展[J].地球物理学进展,20(2):545—549.WANG Xiao-ping,SONG Xiu-qing,QIN Hao-wen.2005.The development and status of the receiver function applica-tion[J].Progress in Geophysics,20(2):545—549(in Chinese).
王卫东.2002.泾阳4.8级地震的构造背景[J].西北地震学报,24(2):145—149.WANG Wei-dong.2002.Tectonic background of JingyangMS4.8earthquake[J].Northwestern Seismological Jour-nal,24(2):145—149(in Chinese).
许卫卫,郑天愉.2002.接收函数方法及研究进展[J].地球物理学进展,17(4):605—613.XU Wei-wei,ZHENG Tian-yu.2002.The receiver function method and its progress[J].Progress in Geophysics,17(4):605—613(in Chinese).
张学民,刁桂苓,王为民,等.2005.陕西省数字地震台下方壳幔速度结构研究[J].华北地震科学,23(2):1—9.ZHANG Xue-min,DIAO Gui-ling,WANG Wei-min,et al.2005.Study on the velocity structure of crust and upper-mantle beneath the digital seismic stations in Shaanxi Province[J].North China Earthquake Sciences,23(2):1—9(in Chinese).
Langston C A.1979.Structure under Mount Rainer,Washington,inferred from teleseismic body waves[J].Journal ofGeophysical Research,84(B9):4749—4762.
Zhu L,Kanamori H.2000.Moho depth variation in southern California from teleseismic receiver functions[J].Jour-nal of Geophysical Research,105(B2):2969—2980.
冯希杰,杜文和,袁志祥,等.2004.陕西石泉2003年4月24日ML4.9地震及其烈度衰减[J].西北地震学报,26(4):365—367.FENG Xi-jie,DUWen-he,YUAN Zhi-xiang,et al.2004.ShiquanML4.9earthquake in Shaanxi Province on April24,2003,and its intensity attenuation[J].Northwestern Seismological Journal,26(4):365—367(in Chinese).
贺传松,王椿镛,吴庆举.2003.接收函数方法及其新的进展[J].地球物理学进展,18(2):224—228.HE Chuan-song,WANG Chun-yong,WU Qing-ju.2003.The receiver function method and its newprogress[J].Pro-gress in Geophysics,18(2):224—228(in Chinese).
姜家兰,黄长林.1986.陕西地区地壳厚度初探[J].西北地震学报,8(4):43—51.JIANG Jia-lan,HUANG Chang-lin.1986.A preliminary study on the crustal thickness in Shaanxi region[J].North-western Seismological Journal,8(4):43—51(in Chinese).
孔繁宗.1991.陕西新构造活动概要[J].中国区域地质,10(1):10—16.KONG Fan-zong.1991.Abrief account of the neotectonic activity in Shaanxi[J].Regional Geology of China,10(1):10—16(in Chinese).
李华,王良书,李成,等.2008.大别造山带西段宽频带数字地震台阵观测与地壳上地幔结构[J].中国科学(D辑),38(7):862—871.LI Hua,WANG Liang-shu,LI Cheng,et al.2008.Structure of the crust and uppermost mantle from broadband seismicarray in the western Dabie Mountains,east central China[J].Science in China(Ser D),38(7):862—871(inChinese).
李永华,吴庆举,田小波,等.2009.用接收函数方法研究云南及其邻区地壳上地幔结构[J].地球物理学报,52(1):67—80.LI Yong-hua,WU Qing-ju,TIAN Xiao-bo,et al.2009.Crustal structure in the Yunnan region determined by modelingreceiver functions[J].Chinese Journal of Geophysics,52(1):67—80(in Chinese).
楼海,王椿镛,吕智勇,等.2008.2008年汶川MS8.0级地震的深部构造环境:远震P波接收函数和布格重力异常的联合解释[J].中国科学(D辑),38(10):1207—1220.LOU Hai,WANG Chun-yong,L Zhi-yong,et al.2008.Deep tectonic setting of the2008WenchuanMS8.0earth-quake in southwestern China-Joint analysis of teleseismic P-wave receiver functions and Bouguer gravity anomalies[J].Science in China(Ser D),38(10):1207—1220(in Chinese).
陕西省地震局.2005.陕西省地震监测志[M].北京:地震出版社.Earthquake Administration of Shaanxi Province.2005.Seismic Monitoring Records of Shaanxi Province[M].Seismo-logical Press,Beijing(in Chinese).
宋立胜.1989.陕西省志:地震志[M].北京:地震出版社.SONG Li-sheng.1989.Shaanxi Provincial Annals:Earthquake[M].Seismological Press,Beijing(in Chinese).
田宝峰,李娟,王卫民,等.2008.华北太行山区地壳各向异性的接收函数证据[J].地球物理学报,51(5):1459—1467.TIAN Bao-feng,LI Juan,WANG Wei-min,et al.2008.Crust anisotropy of Taihangshan mountain range in North Chinainferred from receiver functions[J].Chinese Journal of Geophysics,51(5):1459—1467(in Chinese).
王椿镛,楼海,吕智勇,等.2008.青藏高原东部地壳上地幔S波速度结构:下地壳流的深部环境[J].中国科学(D辑),38(1):22—32.WANG Chun-yong,LOU Hai,L Zhi-yong,et al.2008.S-wave crustal and upper mantle s velocity structure in theeastern Tibetan Plateau-deep environment of lower crustal flow[J].Science in China(Ser D),38(1):22—32(in Chinese).
王小平,宋秀青,秦浩文.2005.接收函数方法应用的现状及其发展[J].地球物理学进展,20(2):545—549.WANG Xiao-ping,SONG Xiu-qing,QIN Hao-wen.2005.The development and status of the receiver function applica-tion[J].Progress in Geophysics,20(2):545—549(in Chinese).
王卫东.2002.泾阳4.8级地震的构造背景[J].西北地震学报,24(2):145—149.WANG Wei-dong.2002.Tectonic background of JingyangMS4.8earthquake[J].Northwestern Seismological Jour-nal,24(2):145—149(in Chinese).
许卫卫,郑天愉.2002.接收函数方法及研究进展[J].地球物理学进展,17(4):605—613.XU Wei-wei,ZHENG Tian-yu.2002.The receiver function method and its progress[J].Progress in Geophysics,17(4):605—613(in Chinese).
张学民,刁桂苓,王为民,等.2005.陕西省数字地震台下方壳幔速度结构研究[J].华北地震科学,23(2):1—9.ZHANG Xue-min,DIAO Gui-ling,WANG Wei-min,et al.2005.Study on the velocity structure of crust and upper-mantle beneath the digital seismic stations in Shaanxi Province[J].North China Earthquake Sciences,23(2):1—9(in Chinese).
Langston C A.1979.Structure under Mount Rainer,Washington,inferred from teleseismic body waves[J].Journal ofGeophysical Research,84(B9):4749—4762.
Zhu L,Kanamori H.2000.Moho depth variation in southern California from teleseismic receiver functions[J].Jour-nal of Geophysical Research,105(B2):2969—2980.
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