2010玉树M_S7.1地震前后青藏高原东缘绝对重力变化
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摘要
2010年4月14日青海省玉树发生MS7.1地震后,中国地震局及时组织实施了地震科学考察,其中对玉树、西宁、姑咱和西昌等4个绝对重力点进行复测,通过比对前期成果,分别给出了2007年以来(地震前后)3～4期各测点H=1.0m(距墩面高)和H=0.0m(墩面)处的绝对重力变化(观测精度均优于3.0×10-8 m.s-2).结合已有区域地质构造运动、地震活动机制、形变测量成果等,主要结论或认识有:1)地震前后(含同震)玉树、姑咱、西昌绝对重力变化明显呈上升变化,玉树点和姑咱点尤为突出;2)同震模拟结果表明,地震前后玉树点绝对重力变化(H=1.0m)与同震破裂效应基本相当;3)从重力变化角度检核了玉树地震左旋破裂运动对羌塘块体东流运动和川滇菱形块体的南东-南南东运动具有明显激励作用,川滇菱形块体北段尤为强烈,南段可能因南南东向运动遇到中部贡嘎山隆起的阻挡吸收而有所减弱.
After the Yushu MS 7.1 earthquake on April 14 th,2010,an earthquake scientific investigation have been executed immediately by China Earthquake Administration.Four absolute gravity stations including Yushu,Xining,Guzan and Xichang have been surveyed.Comparing with previous results,we provide 3 or 4 periods of absolute gravity observation results before and after the earthquake with the precision better than 3.0×10-8 m·s-2,and the results include two cases which are H=1.0 m(height above earth surface to surveying point) and H=0.0 m(earth surface).Considering the local tectonic movement,seismic activity,deformation measurement results and so on,the main conclusion in this paper include: 1)The absolute gravity changes of Yushu,Guzan and Xichang before and after the earthquake are increasing,especially the Yushu and Guzan stations.2)The coseismic simulation results indicate that it's nearly equivalent between the Yushu absolute gravity changes(H=1.0 m) and coseismic rupture effects.3)On the point of view of gravity changes,the left lateral rupture movement of the Yushu earthquake have obvious invigorative effect to the eastward mass flow of Qiangtang block and the southeast-and-south-south-east movement of the Sichuan-Yunnan rhombic block.It's especially intense in the north part of the Sichuan-Yunnan rhombic block,and weakened in the south part,which may caused by the block off Gongga mountain uplift when moving to the south-south-east.
After the Yushu MS 7.1 earthquake on April 14 th,2010,an earthquake scientific investigation have been executed immediately by China Earthquake Administration.Four absolute gravity stations including Yushu,Xining,Guzan and Xichang have been surveyed.Comparing with previous results,we provide 3 or 4 periods of absolute gravity observation results before and after the earthquake with the precision better than 3.0×10-8 m·s-2,and the results include two cases which are H=1.0 m(height above earth surface to surveying point) and H=0.0 m(earth surface).Considering the local tectonic movement,seismic activity,deformation measurement results and so on,the main conclusion in this paper include: 1)The absolute gravity changes of Yushu,Guzan and Xichang before and after the earthquake are increasing,especially the Yushu and Guzan stations.2)The coseismic simulation results indicate that it's nearly equivalent between the Yushu absolute gravity changes(H=1.0 m) and coseismic rupture effects.3)On the point of view of gravity changes,the left lateral rupture movement of the Yushu earthquake have obvious invigorative effect to the eastward mass flow of Qiangtang block and the southeast-and-south-south-east movement of the Sichuan-Yunnan rhombic block.It's especially intense in the north part of the Sichuan-Yunnan rhombic block,and weakened in the south part,which may caused by the block off Gongga mountain uplift when moving to the south-south-east.
引文
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[9]Wang R J,Lorenzo-Martín F,Roth F.PSGRN/PSCMP-a new code for calculation co-and post-seismic deformation,geoid and gravity changes based on the viscoelastic-gravitational dislocation theory[J].Computers and Geosciences,2006,32(4):527-541.
[10]Tanaka Y,Okubo S,Machida M,et al.First detection of absolute gravity change caused by earthquake[J].Geophys.Res.Lett.,2001,28(15):2979-2981.
[11]Imanishi Y,Sato T,Higashi T,et al.A network of superconducting gravimeters detects submicrogal coseismic gravity changes[J].Science,2004,306(5695):476-478.
[12]刘超,许力生,陈运泰.2010年4月14日青海玉树地震快速矩张量解[J].地震学报,2010,32(3):366-368.Liu C,Xu L S,Chen Y T.Quick moment tensor solution for14April2010Yushu,Qinghai,earthquake[J].Acta Seismological Sinica(in Chinese),2010,32(3):366-368.
[13]申重阳,李辉,谈洪波.汶川8.0级地震同震重力与形变效应模拟[J].大地测量与地球动力学,2008,28(5):6-12.Shen C Y,Li H,Tan H B.Simulation of coseismic gravity changes and deformation effect to Wenchuan M S8.0earthquake[J].Journal of Geodesy and Geodynamics(in Chinese),2008,28(5):6-12.
[14]谈洪波,申重阳,李辉,等.汶川大地震震后重力变化和形变的黏弹分层模拟[J].地震学报,2009,31(5):491-505.Tan H B,Shen C Y,Li H,et al.Simulation of post-seismic gravity change and deformation of the Wenchuan earthquake based on viscoelsatic layered half-space model[J].Acta Seismologica Sinica(in Chinese),2009,31(5):491-505.
[15]闻学泽,徐锡伟,郑荣章,等.甘孜-玉树断裂的平均滑动速率与近代大地震破裂[J].中国科学D辑:地球科学,2003,33(增):199-208.Wen X Z,Xu X W,Zhen R Z,et al.Average slip rate and recent earthquake rupture on the Ganzi-Yushu fault zone[J].Science in China(Series D:Earth Sciences)(in Chinese),2003,33(Supp.):199-208.
[16]周荣军,闻学泽,蔡长星,等.甘孜-玉树断裂带的近代地震与未来地震趋势估计[J].地震地质,1997,19(2):115-124.Zhou R J,Wen X Z,Cai C X,et al.Recent earthquakes and assessment of seismic tendency on the Ganzi-Yushu fault zone[J].Seismology and Geology(in Chinese),1997,19(2):115-124.
[17]任俊杰,谢富仁,刘冬英,等.2010年玉树地震的构造环境、历史地震活动及其复发周期估计[J].震灾防御技术,2010,5(2):228-233.Ren J J,Xie F R,Liu D Y,et al.Study of tectonics,seismicity and recurrence interval of Yushu2010earthquake,Qinghai province[J].Technology for Earthquake Disaster Prevention(in Chinese),2010,5(2):228-233.
[18]刁桂苓,王晓山,高国英,等.以震源机制类型划分汶川、玉树地震构造块体归属[J].地球物理学报,2010,53(8):1778-1783.Diao G L,Wang X S,Gao G Y,et al.Tectonic block attribution of Wenchuan and Yushu earthquakes distinguished by focal mechanism type[J].Chinese J.Geophys.(in Chinese),2010,53(8):1778-1783.
[19]李瑞浩,黄建梁,李辉,等.唐山地震前后区域重力场变化机制[J].地震学报,1997,19(4):399-407.Li R H,Huang J L,Li H,et al.The mechanism of regional gravity changes before and after the Tangshan earthquake[J].Acta Seismologica Sinica(in Chinese),1997,19(4):399-407.
[20]徐锡伟,闻学泽,郑荣章,等.川滇地区活动块体最新构造变动样式及其动力来源[J].中国科学D辑,2003,33(增):151-162.Xu X W,Wen X Z,Zhen R Z,et al.Active blocks pattern of latest tectonic motion and its dynamics in Sichuan-Yunnan region[J].Science in China(Series D:Earth Sciences)(in Chinese),2003,33(Supp.):151-162.
[21]谭锡斌,徐锡伟,李元希,等.贡嘎山快速隆升的磷灰石裂变径迹证据及其隆升机制讨论[J].地球物理学报,2010,53(8):1859-1867.Tan X B,Xu X W,Lee Y H,et al.Apatite fission track evidence for rapid uplift of the Gongga Mountain and discussion of its mechanism[J].Chinese J.Geophys.(inChinese),2010,53(8):1859-1867.
[22]尹福光.攀西裂谷内陆盆地自由热对流应力分析及盆地沉降[J].沉积与特提斯地质,2003,23(4):80-83.Yin F G.Free thermal convection and subsidence of the Panxi intracontinental rift basin[J].Sedimentary Geology and Tethyan Geology(in Chinese),2003,23(4):80-83.
[23]何斌,徐义刚,肖龙,等.攀西裂谷存在吗[J]?地质论评,2003,49(6):572-582.He B,Xu Y G,Xiao L,et al.Does the Panzhihua-Xichang rift exit[J]?Geological Review(in Chinese),2003,49(6):572-582.
[24]Wang Q,Zhang P Z,Freymueller J T,et al.Present-day crustal deformation in China constrained by Global Positioning System measurements[J].Science,2001,294(5542):574-577.
[25]Zhang P Z,Shen Z K,Wang M,et al.Continuous deformation of the Tibetan Plateau from global positioning system data[J].Geology,2004,32(9):809-812.
[26]Gan W J,Zhang P Z,Shen Z K,et al.Present-day crustal motion within the Tibetan Plateau inferred from GPS measurements[J].J.Geophys.Res.,2007,112:B08416.
[27]张培震,邓起东,张国民,等.中国大陆的强震活动与活动地块[J].中国科学(D辑),2003,33(增):12-20.Zhang P Z,Deng Q D,Zhang G M,et al.Strong earthquakes and active blocks in the Chinese continent[J].Science in China(Series D:Earth Sciences)(in Chinese),2003,33(Supp.):12-20.
[28]王阎昭,王恩宁,沈正康,等.基于GPS资料约束反演川滇地区主要断裂现今活动速率[J].中国科学(D辑),2008,38(5):582-597.Wang Y Z,Wang E N,Shen Z K,et al.Constrained inversion of major faults at present-day rates by GPS data in the Sichuan and Yunnan region[J].Science in China(Series D:Earth Sciences)(in Chinese),2008,38(5):582-597.
[29]王庆良,崔笃信,王文萍,等.川西地区现今垂直地壳运动研究[J].中国科学D辑,2008,38(5):598-610.Wang Q L,Cui D X,Wang W P,et al.Study of current vertical crustal movement in west Sichun[J].Science in China(Series D:Earth Science)(in Chinese),2008,38(5):598-610.
[2]王勇,张为民,詹金刚,等.重复绝对重力测量观测的滇西地区和拉萨点的重力变化及其意义[J].地球物理学报,2004,47(1):95-100.Wang Y,Zhang W M,Zhan J G,et al.Gravity change detected by repeated absolute gravity measurements in the western Yunnan and Lhasa,China and its implication[J].Chinese J.Geophys.(in Chinese),2004,47(1):95-100.
[3]Sun W K,Wang Q,Li H,et al.Gravity and GPS measurements reveal mass loss beneath the Tibetan Plateau:Geodetic evidence of increasing crustal thickness[J].Geophysical Research Letters,2009,36:L02303,doi:10.1029/2008GL036512.
[4]李辉,申重阳,孙少安,等.中国大陆近期重力场动态变化图像[J].大地测量与地球动力学,2009,29(3):1-10.Li H,Shen C Y,Sun S A,et al.Dynamic gravity change of recent years in China continent[J].Journal of Geodesy and Geodynamics(in Chinese),2009,29(3):1-10.
[5]邢乐林,李辉,何志堂,等.成都基准台绝对重力复测结果分析[J].大地测量与地球动力学,2010,28(6):38-42.Xing L L,Li H,He Z T,et al.Analysis of repeat absolute gravity surveying results at Chengdu earthquake station[J].Journal of Geodesy and Geodynamics(in Chinese),2008,28(6):38-42.
[6]陈立春,王虎,冉勇康,等.玉树MS7.1级地震地表破裂与历史大地震[J].科学通报,2010,50(13):1200-1205.Chen L C,Wang H,Ran Y K,et al.The M S7.1Yushu earthquake surface ruptures and historical earthquake[J].Chinese Sci.Bull.(in Chinese),2010,50(13):1200-1205.
[7]Okubo S.Gravity and potential changes due to shear and tensile faults in a half-space[J].JGR,1992,97(B5):7134-7144.
[8]Sun W K,Okubo S.Surface potential and gravity changes due to internal dislocations in a spherical Earth-I.Theory for a point dislocation[J].Geophys.J.Int.,1993,114(3):569-592.
[9]Wang R J,Lorenzo-Martín F,Roth F.PSGRN/PSCMP-a new code for calculation co-and post-seismic deformation,geoid and gravity changes based on the viscoelastic-gravitational dislocation theory[J].Computers and Geosciences,2006,32(4):527-541.
[10]Tanaka Y,Okubo S,Machida M,et al.First detection of absolute gravity change caused by earthquake[J].Geophys.Res.Lett.,2001,28(15):2979-2981.
[11]Imanishi Y,Sato T,Higashi T,et al.A network of superconducting gravimeters detects submicrogal coseismic gravity changes[J].Science,2004,306(5695):476-478.
[12]刘超,许力生,陈运泰.2010年4月14日青海玉树地震快速矩张量解[J].地震学报,2010,32(3):366-368.Liu C,Xu L S,Chen Y T.Quick moment tensor solution for14April2010Yushu,Qinghai,earthquake[J].Acta Seismological Sinica(in Chinese),2010,32(3):366-368.
[13]申重阳,李辉,谈洪波.汶川8.0级地震同震重力与形变效应模拟[J].大地测量与地球动力学,2008,28(5):6-12.Shen C Y,Li H,Tan H B.Simulation of coseismic gravity changes and deformation effect to Wenchuan M S8.0earthquake[J].Journal of Geodesy and Geodynamics(in Chinese),2008,28(5):6-12.
[14]谈洪波,申重阳,李辉,等.汶川大地震震后重力变化和形变的黏弹分层模拟[J].地震学报,2009,31(5):491-505.Tan H B,Shen C Y,Li H,et al.Simulation of post-seismic gravity change and deformation of the Wenchuan earthquake based on viscoelsatic layered half-space model[J].Acta Seismologica Sinica(in Chinese),2009,31(5):491-505.
[15]闻学泽,徐锡伟,郑荣章,等.甘孜-玉树断裂的平均滑动速率与近代大地震破裂[J].中国科学D辑:地球科学,2003,33(增):199-208.Wen X Z,Xu X W,Zhen R Z,et al.Average slip rate and recent earthquake rupture on the Ganzi-Yushu fault zone[J].Science in China(Series D:Earth Sciences)(in Chinese),2003,33(Supp.):199-208.
[16]周荣军,闻学泽,蔡长星,等.甘孜-玉树断裂带的近代地震与未来地震趋势估计[J].地震地质,1997,19(2):115-124.Zhou R J,Wen X Z,Cai C X,et al.Recent earthquakes and assessment of seismic tendency on the Ganzi-Yushu fault zone[J].Seismology and Geology(in Chinese),1997,19(2):115-124.
[17]任俊杰,谢富仁,刘冬英,等.2010年玉树地震的构造环境、历史地震活动及其复发周期估计[J].震灾防御技术,2010,5(2):228-233.Ren J J,Xie F R,Liu D Y,et al.Study of tectonics,seismicity and recurrence interval of Yushu2010earthquake,Qinghai province[J].Technology for Earthquake Disaster Prevention(in Chinese),2010,5(2):228-233.
[18]刁桂苓,王晓山,高国英,等.以震源机制类型划分汶川、玉树地震构造块体归属[J].地球物理学报,2010,53(8):1778-1783.Diao G L,Wang X S,Gao G Y,et al.Tectonic block attribution of Wenchuan and Yushu earthquakes distinguished by focal mechanism type[J].Chinese J.Geophys.(in Chinese),2010,53(8):1778-1783.
[19]李瑞浩,黄建梁,李辉,等.唐山地震前后区域重力场变化机制[J].地震学报,1997,19(4):399-407.Li R H,Huang J L,Li H,et al.The mechanism of regional gravity changes before and after the Tangshan earthquake[J].Acta Seismologica Sinica(in Chinese),1997,19(4):399-407.
[20]徐锡伟,闻学泽,郑荣章,等.川滇地区活动块体最新构造变动样式及其动力来源[J].中国科学D辑,2003,33(增):151-162.Xu X W,Wen X Z,Zhen R Z,et al.Active blocks pattern of latest tectonic motion and its dynamics in Sichuan-Yunnan region[J].Science in China(Series D:Earth Sciences)(in Chinese),2003,33(Supp.):151-162.
[21]谭锡斌,徐锡伟,李元希,等.贡嘎山快速隆升的磷灰石裂变径迹证据及其隆升机制讨论[J].地球物理学报,2010,53(8):1859-1867.Tan X B,Xu X W,Lee Y H,et al.Apatite fission track evidence for rapid uplift of the Gongga Mountain and discussion of its mechanism[J].Chinese J.Geophys.(inChinese),2010,53(8):1859-1867.
[22]尹福光.攀西裂谷内陆盆地自由热对流应力分析及盆地沉降[J].沉积与特提斯地质,2003,23(4):80-83.Yin F G.Free thermal convection and subsidence of the Panxi intracontinental rift basin[J].Sedimentary Geology and Tethyan Geology(in Chinese),2003,23(4):80-83.
[23]何斌,徐义刚,肖龙,等.攀西裂谷存在吗[J]?地质论评,2003,49(6):572-582.He B,Xu Y G,Xiao L,et al.Does the Panzhihua-Xichang rift exit[J]?Geological Review(in Chinese),2003,49(6):572-582.
[24]Wang Q,Zhang P Z,Freymueller J T,et al.Present-day crustal deformation in China constrained by Global Positioning System measurements[J].Science,2001,294(5542):574-577.
[25]Zhang P Z,Shen Z K,Wang M,et al.Continuous deformation of the Tibetan Plateau from global positioning system data[J].Geology,2004,32(9):809-812.
[26]Gan W J,Zhang P Z,Shen Z K,et al.Present-day crustal motion within the Tibetan Plateau inferred from GPS measurements[J].J.Geophys.Res.,2007,112:B08416.
[27]张培震,邓起东,张国民,等.中国大陆的强震活动与活动地块[J].中国科学(D辑),2003,33(增):12-20.Zhang P Z,Deng Q D,Zhang G M,et al.Strong earthquakes and active blocks in the Chinese continent[J].Science in China(Series D:Earth Sciences)(in Chinese),2003,33(Supp.):12-20.
[28]王阎昭,王恩宁,沈正康,等.基于GPS资料约束反演川滇地区主要断裂现今活动速率[J].中国科学(D辑),2008,38(5):582-597.Wang Y Z,Wang E N,Shen Z K,et al.Constrained inversion of major faults at present-day rates by GPS data in the Sichuan and Yunnan region[J].Science in China(Series D:Earth Sciences)(in Chinese),2008,38(5):582-597.
[29]王庆良,崔笃信,王文萍,等.川西地区现今垂直地壳运动研究[J].中国科学D辑,2008,38(5):598-610.Wang Q L,Cui D X,Wang W P,et al.Study of current vertical crustal movement in west Sichun[J].Science in China(Series D:Earth Science)(in Chinese),2008,38(5):598-610.
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