SEISMOLOGY AND EGOLOGY ›› 2002, Vol. 24 ›› Issue (4): 565-570.

• Brief Report • Previous Articles     Next Articles

SHALLOW SEISMIC EXLORATION OF THE ACTIVE LIUWU-DAFOSI FAULT IN THE VICINITY OF LHASA CITY

MA Wen-tao1, LING Hong1, CAO Zhong-quan2, CHU Bao-gui1, ZHANG Lan-feng 1   

  1. 1. Institute of Geology, China Seismological Bureau, Beijing 100029, China;
    2. Seismological Bureau of the Xizang Autonomous Region, Lhasa 650000, China
  • Received:2002-03-07 Revised:2002-08-29 Online:2002-12-03 Published:2009-10-26

拉萨市附近刘吾大佛寺间断裂的浅层地震勘探

马文涛1, 凌宏1, 曹忠权2, 储宝贵1, 张兰凤1   

  1. 1. 中国地震局地质研究所, 北京, 100029;
    2. 西藏自治区地震局, 拉萨, 850000
  • 作者简介:马文涛,男,1958年3月生,1982年毕业于云南大学地球物理专业,1996年在中国地震局地质研究所获构造物理学博士学位,副研究员,现主要研究方向为地震学和地球物理学及其在活动构造中的运用和地震动力学模型,电话:010-62009416,E-mail:wentaoma@sina.com.cn.
  • 基金资助:
    国家发展计划委员会高新技术项目(2001977);国家重点基础研究发展规划项目(G1998040701);西藏自治区地震局共同资助.

Abstract: This paper demonstrates the results of shallow seismic exploration of the Liuwu-Dafosi Fault in the vicinity of Lhasa City. On spot map, the segment of the fault in mountainous area can be identified distinctly, but the segment in river valley is unidentified. Shallow seismic exploration reveals that the fault dissects Tertiary or Quaternary strata. Geological interpretation of shallow seismic reflection profile reveals a velocity structure of five layers. Layer 1 to layer 4 have a velocity ranging from 0.8km/s to 2.0km/s or 2.8km/s, and can be assigned to Tertiary or Quaternary strata. Layer 5 has a velocity ranging from 3.0km/s to 4.0km/s, which is supposed to be granite bedrock according to its scattered distribution in CDP stacked section and geological evidence. The Liuwu-Dafosi Fault can be identified at 320m distance of the shallow seismic reflection profile located to the southwest of the Lhasa City. The fault is dipping northeast at an angle of 80?, the highest point of which is at 100m depth. It is determined that the fault is an active reverse fault.

Key words: shallow seismic exploration, active fault, Lhasa City

摘要: 简要介绍了在青藏高原拉萨市附近刘吾-大佛寺间断裂的浅层地震勘探工作,并进行了初步的地质解释.结果表明,刘吾-大佛寺间断裂所在区域的速度模型为5层结构.第1层至第4层的介质深度从0m变化到20m,P波速度800~2 000或2 800m/s,介质为第四纪或第三纪覆盖层;第5层的介质P波速度在3 000~4 000m/s以上,其CDP图像分布零散、没有形成较强的反射界面,推测该区域为花岗岩类的基岩区.根据反射波组的连贯性、间断性及位置,判定在浅层地震勘探剖面320m处存在着刘吾-大佛寺间断裂,它是1条逆断层,倾向NE,倾角80°左右,其上端点出现在深约100m处.

关键词: 浅层地震勘探, 活断层, 拉萨地区

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