SEISMOLOGY AND GEOLOGY ›› 2014, Vol. 36 ›› Issue (4): 1145-1156.DOI: 10.3969/j.issn.0253-4967.2014.04.017

• CONTENTS • Previous Articles     Next Articles

CRUSTAL DENSITY STRUCTURE OF YUNNAN LUDIAN MS6.5 EARTHQUAKE AREA

YANG Guang-liang1,2,3, SHEN Chong-yang2,3, TAN Hong-bo2,3, WANG Jia-pei2,3, WU Gui-ju2,3   

  1. 1. Key Laboratory of Computational Geodynamics, Chinese Academy of Sciences, Beijing 100049, China;
    2. Key Laboratory of Earthquake Geodesy, Institute of Seismology, CEA, Wuhan 430071, China;
    3. Wuhan Base of Institute of Crustal Dynamics, China Earthquake Administration, Wuhan 430071, China
  • Received:2014-12-01 Online:2014-12-30 Published:2015-01-07

云南鲁甸MS6.5地震震区地壳密度结构特征

杨光亮1,2,3, 申重阳2,3, 谈洪波2,3, 王嘉沛2,3, 吴桂桔2,3   

  1. 1. 中国科学院计算地球动力学重点实验室, 北京 100049;
    2. 中国地震局地壳应力研究所武汉科技创新基地, 武汉 430071;
    3. 地震大地测量重点实验室, 武汉 430071
  • 通讯作者: 申重阳,研究员,主要从事重力与地球动力学研究,E-mail:scy907@163.com
  • 作者简介:杨光亮,男,1980年生,中国科学院大学博士后、湖北省地震局副研究员,主要从事重力与地球动力学研究,E-mail:vforyang@gmail.com.
  • 基金资助:

    国家自然科学基金(41204014,41274141)、国家重点基础研究发展规划计划(2013CB733304)、中国地震局行业重大专项(201308011)和中国地震局"云南鲁甸6.5级地震专题研究"项目共同资助.

Abstract:

In this paper, based on three gravity profiles in Yunnan Ludian MS6.5 earthquake and adjacent area, we obtained Bouguer gravity anomaly, residual density correlation image and crustal stratification structure along the profiles. The study shows a saddle-shaped distribution of Bouguer gravity anomalies along the Huili-Ludian-Zhaotong, Panzhihua-Menggu-Dajing and Shekuai-Tangdan-Huize profile, with the values ranging -278~-197×10~5ms-2, -273~-200×10~5ms-2, -280~-254×10~5ms-2, respectively; the local low values locate in the Xiaojiang fault zone, the amplitude difference decreases gradually from the north to the south; the density in the Xiaojiang fault zone is lower than that of the sides, the low density zone extends to the middle and lower crust, and the material density in the east is lower than that in the west; positive and negative density anomalies overlap, indicating a poor stability of the lower crust. The Ludian earthquake occurred in this region. Layered crustal structure shows the undulation of Moho surface, with uplift beneath the Xiaojiang fault zone as the center and change of the maximum depth of Moho from 50km up to 41km from north to south. This reflects the position of Xiaojiang Fault in the regional geological structure as block boundary of Sichuan-Yunnan block and South China block.

Key words: Ludian earthquake, gravity profile, Bouguer anomaly, crustal structure

摘要:

基于云南鲁甸MS6.5地震震区的3条 "工" 字形剖面的重力与GPS观测数据, 获得了沿剖面的布格重力异常、剩余密度相关成像和地壳密度分层结构.研究表明, 会理—鲁甸—昭通、攀枝花—蒙姑—大井、舍块—汤丹—会泽剖面布格重力变化范围分别为-278~-197×10-5ms-2、-273~-200×10-5ms-2、-280~-254×10-5ms-2, 均呈"鞍"形分布, 其局部低值均位于小江断裂带附近, 且幅度差自北向南逐渐减小.小江断裂带内物质密度低于两侧, 低密度体扩展至中下地壳, 且其东侧物质密度低于西侧, 密度异常体呈正负交迭, 地壳稳定性低, 鲁甸震区处于该区域内.地壳分层结构显示莫霍面以小江断裂带为中心向上抬升, 莫霍面最大深度自北向南从50km抬升至41km, 反映了小江断裂带在区域地质构造中的地位——川滇块体与华南块体的分界线.

关键词: 鲁甸地震, 重力剖面, 布格异常, 地壳结构

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