2015年尼泊尔M_S8.1地震的地壳重力均衡背景与地表形变响应特征
详细信息 本馆镜像全文    |  推荐本文 | | 获取馆网全文
摘要
对2015年尼泊尔MS8.1地震的地壳均衡背景及其引起的地表形变特征进行了研究,结果表明:(1)尼泊尔MS8.1地震震中以南的印度板块岩石圈有效弹性厚度大约为9km,加载主要来自地幔;地震以北的拉萨地块岩石圈有效弹性厚度大约为2km,加载主要来自地表.(2)尼泊尔MS8.1地震震中以南地区的地壳均衡异常大约为-100mGal(10-5 m·s-2),但其北部的地壳均衡异常则为300~400mGal,尼泊尔MS8.1地震发生在地壳均衡负异常向正异常过渡的高梯度带上.(3)尼泊尔MS8.1地震使震中周围地区的地壳整体向南运动,最大水平位移超过1.5m,分布在震中东南.震中以北的同震垂向位移总体为负值,最大下降幅度超过0.5m,同震重力变化总体为正值,最大超过60μGal(10-8 m·s-2);震中以南的垂向位移总体为正值,最大升幅超过0.7m,同震重力变化总体为负值,最大降幅超过-120μGal.(4)尼泊尔MS8.1地震使"世界屋脊"喜马拉雅山脉产生沉降,最大同震降幅超过120mm,震后松弛效应将使"世界屋脊"持续缓慢下降.该强震使世界最高峰珠穆朗玛峰降低了2~3mm,有可能被GPS、InSAR等现代大地测量工具检测到.
We studied the gravitational isostasy background and the surface deformation response characteristics of the 2015 Nepal MS8.1earthquake.The results showed that:(1)the lithosphere effective elastic thickness of Indian block,an area south to the epicenter of 2015 Nepal MS8.1earthquake,is about 9 km,and the load comes mainly from the mantle. However,the lithosphere effective elastic thickness of Lhasa block,an area north to the great earthquake,is about 2km,and the load comes mainly from the tomography.(2)The gravitational isostasyanomalies are about-100 mGal(10-5 m·s-2)at area south to the Nepal MS8.1earthquake,while at area north to the earthquake,the values become 300~400 mGal.The Nepal MS8.1earthquake occurred at a high gradient belt where the isostasy varies from negative anomalies to positive anomalies.(3)Due to the Nepal MS8.1earthquake,the earth surface around the epicenter moved southward as a whole.The maximum of the co-seismic horizontal displacements is above 1.5m,located at the area southeast to the epicenter.At the area north to the epicenter,the co-seismic vertical displacements are negative and the maximum exceeds-0.5m,the gravity changes are positive and the maximum is above 60μGal(10-8 m·s-2).However,the values at the area south to the epicenter are vice versa.The maximum co-seismic vertical displacements and gravity changes are 0.7mand-120μGal respectively.(4)The Nepal MS8.1earthquake made the roof of the world,the Himalayas,decease as a whole,and the maximum decrease magnitude is more than 120 mm.It is expected the Himalayas will continue to decrease because of the relaxation effects of the mantle.The Nepal MS8.1earthquake made Mt.Everest decrease about2~3mm,which may be detectable by modern measuring tool such as GPS and InSAR.
引文
Bai Z M,Zhang S F,Braitenberg C.2013.Crustal density structurefrom 3Dgravity modeling beneath Himalaya and Lhasa blocks,Tibet.J.Asian Earth Sci.,78:301-317.
    Bollinger L,Sapkota S N,Tapponnier P,et al.2014.Estimatingthe return times of great Himalayan earthquakes in easternNepal:Evidence from the Patu and Bardibas strands of the MainFrountal Thrust.J.Geophys.Res.,119:7123-7163.
    Chen S,Wang Q S,Zhu Y Q,et al.2011.Temporal and spatialfeatures of isostasy anomaly using gravitational admittance modelat eastern margin of Tibetan Plateau.Chinese J.Geophys.(inChinese),54(1):22-34.
    Dziewonski A M,Anderson D L.1981.Preliminary reference earthmodel.Phys.Earth Planet.Inter.,25(4):297-356.
    Fielding E J,McKenzie D.2012.Lithospheric flexure in the SichuanBasin and Longmen Shan at the eastern edge of Tibet.Geophys.Res.Lett.,39(9):doi:10.1029/2012GL051680.
    Fu G Y,Sun W K.2012.Overall design and specific structures ofthe computing codes for coseismic deformations on a layeredspherical earth.Earthquake(in Chinese),32(2):73-87.
    Fu Y T,Li J L,Zhou H,et al.2000.Comments on the effectiveelastic thickness of continental lithosphere.Geological Review(in Chinese),46(2):149-159.
    Hu M Z,Li J C,Li H,et al.2015.The lithosphere effective elasticthickness and its tectonic implications in the NorthwesternPacific.Chinese.J.Geophys.(in Chinese),58(2):542-555.
    Ji C,Wald D J,Helmberger D V.2002.Source description of the1999 Hector Mine,California,earthquake;Part I:Waveletdomain inversion theory and resolution analysis.Bull.Seism.Soc.Am.,92(4):1192-1207.
    McKenzie D.2003.Estimating Tein the presence of internal loads.J.Geophys.Res.,108(B9):doi:10.1029/2002JB001766.
    Okada Y.1985.Surface deformation due to shear and tensile faultsin a half-space.Bull.Seism.Soc.Am.,75(4):1135-1154.
    Shi Y L,Cao J L.2008.Effective viscosity of China continentallithosphere.Earth Science Frontiers(in Chinese),15(3):82-95.
    Steketee J A.1958.On Volterra′s dislocations in a semi-infiniteelastic medium.Can.J.Phys.,36(2):192-205.
    Sun W,Okubo S,Vanicek P.1996.Global displacements caused bypoint dislocations in a realistic earth model.J.Geophys.Res.,101(B4):8561-8577.
    Sun W K,Okubo S,Fu G Y,et al.2009.General formulations ofglobal co-seismic deformations caused by an arbitrary dislocationin a spherically symmetric earth model-applicable to deformedearth surface and space-fixed point.Geophys.J.Int.,177(3):817-833.
    Tanaka T,Okuno J,Okubo S.2006.A new method for thecomputation of global viscoelastic post-seismic deformation in arealistic earth model(I)—vertical displacement and gravityvariation.Geophys.J.Int.,164(2):273-289.
    Tanaka T,Okuno J,Okubo S.2007.A new method for thecomputation of global viscoelastic post-seismic deformation in arealistic earth model(II)—horizontal displacement.Geophys.J.Int.,170(3):1031-1052.
    Thomson D J.1982.Spectrum estimation and harmonic analysis.Proceedings of the IEEE,70(9):1055-1096.
    Wang Q,You X Y,Wang W Y,et al.1998.GPS measurement andcurrent crustal movement across the Himalaya.Crustal Deformationand Earthquake(in Chinese),18(3):43-50.
    Watts A B.2001.Isostasy and Flexure of the Lithosphere.Cambridge:Cambridge University Press.
    Yang T,Fu R S,Huang J S.2012.On the inversion of effectiveelastic thickness of the lithosphere with Moho relief andtopography data.Chinese J.Geophys.(in Chinese),55(11):[22]3671-3680.
    Zhang B,Cheng H H,Shi Y L.2015.Calculation of the co-seismiceffect of MS8.1earthquake,Apirl 25,2015,Nepal.ChineseJournal Geophysics,58(5):1794-1803,doi:10.6038/cjg20150529.
    Zhang G Q,Fu G Y,Zhou X,et al.2015.Retrieve post-seismicgravity changes induced by Sumatra earthquake(Mw9.3)basedon the viscoelastic dislocation theory.Chinese J.Geophys.(inChinese),58(5):1654-1665.
    陈石,王谦身,祝意青等.2011.青藏高原东缘重力导纳模型均衡异常时空特征.地球物理学报,54(1):22-34.
    付广裕,孙文科.2012.球体位错理论计算程序的总体设计与具体实现.地震,32(2):73-87.
    付永涛,李继亮,周辉等.2000.大陆岩石圈有效弹性厚度研究综述.地质论评,46(2):149-159.
    胡敏章,李建成,李辉等.2015.西北太平洋岩石圈有效弹性厚度及其构造意义.地球物理学报,58(2):542-555.
    石耀霖,曹建玲.2008.中国大陆岩石圈等效粘滞系数的计算和讨论.地学前缘,15(3):82-95.
    王琪,游新兆,王文颖等.1998.跨喜马拉雅的GPS观测与地壳形变.地壳形变与地震,18(3):43-50.
    杨亭,傅容珊,黄金水.2012.利用Moho面起伏及地表地形数据反演岩石圈有效弹性厚度的莫霍地形导纳法(MDDF).地球物理学报,55(11):3671-3680.
    张贝,程惠红,石耀霖.2015.2015年4月25日尼泊尔MS8.1大地震的同震效应.地球物理学报,58(5):1794-1803,doi:10.6038/cjg20150529.
    张国庆,付广裕,周新等.2015.利用震后黏弹性位错理论研究苏门答腊地震(Mw9.3)的震后重力变化.地球物理学报,58(5):1654-1665.

版权所有:© 2023 中国地质图书馆 中国地质调查局地学文献中心