SEISMOLOGY AND GEOLOGY ›› 2009, Vol. 31 ›› Issue (2): 207-217.DOI: 10.3969/j.issn.0253-4967.2009.02.001

• Application of new techniques •     Next Articles

THE PLATE SUBDUCTION AND STRESS STATE IN THE PAMIR-HINDU KUSH REGION

SUN Wen-bin1, HE Yue-shi2, CHANG Zheng1, QI Xiao-yan1   

  1. 1. Earthquake Administration of Heilongjiang Province, Harbin 150090, China;
    2. Mudanjiang Seismic Station, Mudanjiang 157009, China
  • Received:2008-05-13 Revised:2008-09-07 Online:2009-03-11 Published:2009-11-27

帕米尔—兴都库什地区板块俯冲及其应力状态

孙文斌1, 和跃时2, 常征1, 齐晓燕1   

  1. 1. 黑龙江省地震局, 哈尔滨, 150090;
    2. 牡丹江地震台, 牡丹江, 157009
  • 作者简介:孙文斌,男,1949生,1975年毕业于长春地质学院物探专业,研究员,主要研究方向为深源地震、俯冲带及地球动力学,电话:0451-82645302,E-mail:sunwb2006@163.com.
  • 基金资助:
    地震科学联合基金(A08131)资助

Abstract: In this paper,the collision configuration between Indian plate and Eurasian plate was studied in detail and the focal mechanism solutions of the earthquakes were analyzed by using the earthquake catalogues from 1973 to 2006 provided by NEIC and focal mechanism solutions from 1978 to 2005 provided by Harvard University.The results indicate that:Eurasian plate was underthrust southwards with a dip of 50?,and the maximum focal depth is 364km;Indian plate collided with Eurasian plate by means of interlayer intercalation.The collision was strong among the Pamir knot,where the seismic activities were enhanced significantly.The focal profile shows a "V-shape" distribution;on the sides of the Pamir knot,the seismic activities decreased apparently along with the decreasing subduction force of the Indian plate.The focal profile indicates that the profile configuration of the northward-subduction of the Indian plate disappeared gradually and the profile configuration of the southeastward-subduction of the Eurasian plate is more perspicuous.The analysis on the distribution pattern of the focal profile suggests that the Indian plate did not penetrate the Eurasian plate.The repeated multi-period and imbricate distribution of earthquake may be the reflection of the process of northward-subduction,detachment,and then re-subduction and re-detachment of the Indian plate.As a result of strong collision and extrusion between Indian plate and Eurasian plate,Pamir-Hindukush region is under a tectonic stress state of near-NS compression.The number of reverse faults accounts for about 70%of the total,the normal faults account for about 11%,and the strike-slip faults,about 19%.The predominant orientation of P axis indicates that the principal compressive stress is oriented near-NS,the dip is near-horizontal,inclining from south to north;and the dip of T axis is near-vertical,similar to the dip of subduction zone.Characteristics of stress field in Pamir-Hindukush show that the active northward-extrusion of Indian plate is the main dynamics of the regional stress field,and the Eurasian plate which dips southward is in a state of passive extrusion.

Key words: focal mechanism solutions, Wadati-Benioff zone, the Pamir-Hindu Kush region

摘要: 利用美国国家地震信息中心(NEIC)提供的1973—2006年地震目录、哈佛大学提供的1978—2005年地震机制解资料,精细地研究了帕米尔—兴都库什地区印度板块与欧亚板块的碰撞形态,分析了地震震源机制特征。研究结果认为:欧亚板块以约50°的倾角向南俯冲,地震最大深度为364km;印度板块以层间插入的方式与欧亚板块碰撞,在帕米尔"结"附近碰撞强烈,地震活动明显增强,震源剖面显示"V"字型分布形态;在帕米尔"结"两侧,随着印度板块俯冲动力减弱,地震活动也明显减弱,地震震源剖面显示,印度板块向北俯冲的剖面形态逐渐消失,欧亚板块向SE俯冲的剖面形态越加清晰,从地震震源剖面分布形态分析,印度板块没有穿过欧亚板块,印度板块向北的反复、多期的叠瓦式地震分布形态,可能反映印度板块向北俯冲→断离、再俯冲→再断离的过程。由于印度板块与欧亚板块间的强烈碰撞挤压作用,帕米尔—兴都库什地区处于以近SN向的挤压构造应力状态,逆断层数量约占70%,正断层数量约占11%,走滑断层数量约占19%。P轴优势方位显示帕米尔—兴都库什地区主压应力近SN向,倾角近水平,呈现由南向北倾斜;T轴倾角近垂直,整体接近俯冲带的倾向。帕米尔—兴都库什地区应力场特征表明,印度板块向北的主动推挤,是形成这一区域应力场的主动力,向南倾的欧亚板块处于一种被动的被挤压状态。

关键词: 震源机制解, Wadati-Benioff带, 帕米尔—兴都库什地区

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