P波极性揭示的甘东南地区构造应力场特征
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摘要
通过分析甘东南宽频带流动台阵以及周边固定台站2010年11月1日-2011年11月30日记录的大量近震资料,对区域地震进行了重新定位。根据P波极性数据推断了甘东南地区主应力轴方向,给出了0.25°×0.25°的构造应力场方向。结果显示,甘东南地区最大主压应力轴表现出旋转特性。最大主压应力轴由北部的NEE向逐渐向南部偏转为近EW向和SEE向。结合该区域其它结果讨论了本区域应力场的成因机制。
To determine the crustal stress field based on the basis of earthquake waves,we analyze data from fixed seismic stations in Gansu and surrounding provinces and the broadband portable seismic array in southeast Gansu province,where three blocks converge to create complex tectonic conditions.Two methods used to directly obtain such stress fields include those based on focal mechanism data and p-wave first motion data.In order effectively use small and microscale earthquake data,the latter method is used in our study.On the basis of near earthquake observation data recorded from November 1,2010,to November 30,2011,we use Zhang's Method to relocate earthquakes occurring in this area.As a result,2 379 earthquakes and 12 129 p-wave polarity data are obtained through which the directions of principal stress axes are inferred.The inversion method and program are provided by Wan.Our study assumes a relative stress value of 0.5.We calculate only the 2-D stress field because most earthquakes have occurred in the research area at depths of 5~20 km;the average depth of 12 km was chosen as the calculating depth.The direction of tectonic stress field in a 0.25° × 0.25° grid in this area is presented for the first time.The orientation of P,B,and T axis azimuths are obtained by 1° × 1° × 1° grid searching.We treat these azimuths as stress flied directions when the contradictory ratio is the smallest.Results show that the maximum compressive stress axis strikes are presented in a radiated pattern;that is,they strike east-west from NEE in northern part to SEE in the east.These findings are similar to that reported in previous research,through which we can infer that the Qinghai-Tibet plateau moving to the northeast encountered the stable Ordos block and the South China block moving to the southeast;thus,the material moved southeast.The earthquakes occurring in this region were fewer and smaller than those west of 104° E;therefore,the stress field inversion result is primarily obtained from smoothing the results of surrounding areas.However,further analysis is necessary to explain why the principal compressive stress axes are steeper here;such research will be the focus of our next investigation.Maximum principal compressive stress axes are steep on the southwestern margin of the Ordos block likely because the material moved east along the West Qinling fault;therefore,the stress environment is tensional.Because the broadband portable seismic array in the southeast area of Gansu province covers density,the constraint mechanism and inversion results are reliable.Detailed characteristics and a relatively reliable direction of the tectonic stress field in southeast Gansu province are obtained in this research.We expect that our results are significant to geological background explanation and earthquake prediction research.
引文
[1]Aki K.Earthquake Generating Stress in Japan for the Years1961to 1963 Obtained by Smoothing First Motion Patterns[J].Bull.Earthq.Res.Inst.,1966,44:447-471.
    [2]李钦祖,王泽皋,贾云年,等.由单台小地震资料所得两个区域的应力场[J].地球物理学报,1973,16:49-61.LI Chin-tsu,WANG Tse-kao,CHIA Yun-nian,et al.StressField Obtained for Two Regions from Weak Earthquake DataRecorded at a Single Seismic Station[J].Acta Geophysica Sini-ca,1973,16:49-61.
    [3]许忠淮,刘玉芬,张郢珍.京津唐张地区地震应力场的方向特征[J].地震学报,1979,1(2):121-132.XU Zhong-huai,LIU Yuv-fen,ZHANG Ying-zhen.On theCharacteristic of Direction of the Earthquake Stress Field A-round the Beijing Area[J].Acta Seismological Sinica,1979,1(2):121-132.
    [4]Xu Z H,Wang S Y,Huang Y R,et al.Tectonic Stress Fieldof China Inferred from a Large Number of Small Earthquakes[J].J Geophys Res,1992,97(B8):11827-11877.
    [5]许忠淮,汪素云,黄雨蕊,等.由大量地震的资料推断我国大陆构造应力场[J].地球物理学报,1989,32(6):636-647.XU Zhong-huai,WANG Su-yun,HUANG Yu-rui,et al.TheTectonic Stress Field of Chinese Continent Deduced from aGreat Number of Earthquakes[J].Acta Geophysica Sinica,1989,32(6):636-647.
    [6]袁道阳,张培震,刘百篪,等.青藏高原东北缘晚第四纪活动构造的几何图像与构造转换[J].地质学报,2004,78(2):270-278.YUAN Dao-yang,ZHANG Pei-zhen,LIU Bai-chi,et al.Geo-metrical Imagery and Tectonic Transformation of Late Quater-nary Active Tectonics in Northeastern Margin of Qinghai-Xi-zang Plateau[J].Acta Geologica Sinica,2004,78(2):270-278.
    [7]邓起东,张培震,冉永康,等.中国活动构造基本特征[J].中国科学(D辑),2002,32(12):1020-1031.DENG Qi-dong,ZHANG Pei-zhen,RAN Yong-kang,et al.Basic Characteristics of Active Tectonics of China[J].Sciencein China(Ser D),2002,32(12):1020-1031.
    [8]刘小凤,梅秀苹,冯建刚,等.青藏高原北部地区地震基本活动状态定量评价[J].西北地震学报,2011,33(2):130-136.LIU Xiao-feng,MEI Xiu-ping,FENG Jiang-gang,et al.Quantitative Estimating Basic State of Seismicity in NorthernRegion of Qinghai-Xizang Plateau[J].Northwestern Seismo-logical Journal,2011,33(2):130-136.
    [9]万永革,吴逸民,盛书中,等.P波极性数据所揭示的台湾地区三维应力结构的初步结果[J].地球物理学报,2011,54(11):281-218.WAN Yong-ge,WU Yih-min,SHENG Shu-zhong,et al.Pre-liminary Result of Taiwan 3-D Stress Field from P Wave Polar-ity Data[J].Chinese J.Geophysics,2011,54(11):2810-2818.
    [10]惠少兴,张元生,李顺成.t-D地震定位方法研究[J].西北地震学报,2012,34(1):10-13.HUI Shao-xing,ZHANG Yuan-sheng,LI Shun-cheng.Study on t-D Earthquake Location Method[J].NorthwesternSeismological Journal,2012,34(1):10-13.
    [11]沈正康,王敏,甘卫军,等.中国大陆现今构造应变率场及其动力学成因研究[J].地学前缘,2003,10(特刊):93-100.SHEN Zheng-kang,WANG Min,GAN Wei-jun,et al.Con-temporary Tectonic Strain Rate Field of Chinese Continentand Its Geodynamic Implication[J].Earth Science Frontiers,2003,10(Suppl):93-100.
    [12]江在森,马宗晋,张希,等,GPS初步结果揭示的中国大陆水平应变场与构造变形[J].地球物理学报,2003,16(3):352-358.JIANG Zai-sen,MA Zong-jin,ZHANG Xi,et al.HorizontalStrain Field and Tectonic Deformation of China Mainland Re-vealed by Preliminary GPS Result[J].Chinese J.Geophys-ics,2003,16(3):352-358.
    [13]江在森,马宗晋,张希,等.青藏块体东北缘水平应变场与构造变形分析[J].地震地质,2001,23(3):337-345.JIANG Zai-sen,MA Zong-jin,ZHANG Xi,et al.Analysisof Recent Horizontal Crustal Strain Field and Tectonic De-formation in the Northeast Margin of Qinghai-Tibet Block[J].Seismology and geology,2001,23(3):337-345.
    [14]许忠淮,汪素云,高阿甲.地震活动反应的青藏高原东北地区现代构造运动特征[J].地震学报,2000,22(5):472-481.XU Zhong-huai,WANG Su-yun,GAO A-jia.Present-dayTectonic Movement in the Northeastern Margin of the Qing-hai-Xizang(Tibetan)Plateau as Revealed by EarthquakeActivity[J].Acta Seismological Sinica,2000,22(5):472-481.
    [15]Yongge WAN.Contemporary Tectonic Stress Field in China[J].Earthq.Sci.,2010,23:377-386.
    [16]徐纪人,赵志新,石川有三.中国大陆地壳应力场与构造运动区域特征研究[J].地球物理学报,2008,51(3):770-781.XU Ji-ren,ZHAO Zhi-xin,Ishikawa Yuzo.Regional Charac-teristics of Crustal Stress Field and Tectonic Motions in andAround Chinese Mainland[J].Chinese J.Geophysics,2008,51(3):770-781.
    [17]常利君,王椿镛,丁志峰,等.青藏高原东北缘上地幔各向异性研究[J].地球物理学报,2008,51(2):431-437.CHANG Li-jun,WANG Chun-yong,DING Zhi-feng,et al.Seismic Anisotropy of Upper Mantle in the NortheasternMargin of the Tibetan Plateau[J].Chinese J.Geophysics,2008,51(2):431-437.
    [18]张辉,高原,石玉涛,等.基于地壳介质各向异性分析青藏高原东北缘构造应力特征[J].地球物理学报,2012,55(1):95-104.ZHANG Hui,GAO Yuan,SHI Yu-tao,et al.TectonicStress Analysis Based on the Crustal Seismic Anisotropy inthe Northeastern Margin of Tibetan plateau[J].Chinese J.Geophysics,2012,55(1):95-104.
    [19]张辉,王熠熙,冯建刚.甘东南地区地壳介质各向异性特征[J].西北地震学报,2011,32(2):112-116.ZHANG Hui,WANG Yi-xi,FENG Jian-gang.Seismic Ani-sotropy in the Crust in Southeastern Area of Gansu Province[J].Northwestern Seismological Journal,2011,32(2):112-116.
    [20]张培震,王琪,马宗晋.中国大陆现今构造运动的GPS速度场和活动地块[J].地学前缘,2002,9(2):430-441.ZHANG Pei-zhen,WANG Qi,MA Zong-jin.GPS VelocityField and Active Crustal Blocks of Contemporary TectonicDeformation in Continental China[J].Earth Science Fron-tiers,2002,9(2):430-441.
    [21]万永革,盛书中,许雅儒,等.不同应力状态和摩擦系数对综合P波辐射花样影响的模拟研究[J].地球物理学报,2011,54(4):994-1001.WAN Yong-ge,SHENG Shu-zhong,HSU Ya-ju,et al.Effect of Stress Ratio and Friction Coefficient on Composite PWave Radiation Patterns[J].Chinese J.Geophysics,2011,54(4):994-1001.
    [22]葛伟鹏,袁道阳,张元生,等.三维地壳结构数据库设计及模型构建——以青藏高原东北缘地震层析成像数据为例[J].西北地震学报,2011,33(1):26-32.GE Wei-peng,YUAN Dao-yang,ZHANG Yuan-sheng,etal.Database Design and Modeling of 3DCrustal Structure:Based on the Seismic Tomographic Data in the NortheastMargin of Tibetan Plateau[J].Northwestern SeismologicalJournal,2011,33(1):26-32.
    [23]周民都,王椿镛,曾融生.青藏高原东北缘地壳上地幔速度结构的地震层析成像研究[J].西北地震学报,2012,34(3):224-233.ZHOU Min-du,WANG Chun-rong,ZENG Rong-sheng.Seismic Tomography of the Velocity Structure of the Crustand Upper Mantle in Northeastern Margin of the Qinghai-Tibet Plateau[J].Northwestern Seismological Journal,2012,34(3):224-233.

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