宁夏及邻区地壳上地幔结构特征分析  

Analysis of Crust and Upper Mantle Structure in Ningxia and its Adjacent Area

作　　者：谢晓峰[1] 王伟涛[2] 崔瑾[1] 吕俊强[1] 姚琳[1] 

机构地区：[1]宁夏回族自治区地震局,宁夏银川750001 [2]中国地震局地球物理研究所,北京100081

出　　处：《地震工程学报》2014年第2期309-313,337,共6页China Earthquake Engineering Journal

基　　金：中国地震局科技星火计划(XH12052);国家自然科学基金(41104027);大地测量与地球动力学国家重点实验室开放基金(SKLGED2014-5-8-E)

摘　　要：介绍了宁夏及邻区1970年以来多种地球物理探测研究成果,揭示了该地区不同活动构造单元的深部地壳构造背景。分析表明,活动块体相互作用、地壳深部断裂、地壳低速体、速度结构的差异和岩性的不同、上地幔顶部隆起、莫霍界面较大的起伏以及复杂的壳幔过渡带等构造特征与该区域强震的形成和发生有较为密切的关系。最后讨论了该区域强震发生的机理。Ningxia and its neighboring area are located in three blocks including the Erdos block, Alashan block and the Qinghai--Xizang block. There are many active faults in this area, such as the Haiyuan fault, the eastern piedmont fault of Helanshan, the Huanghe fault, and the Liupans- han fault. Because of the special stress environment in this area, all earthquakes of magnitude greater than 8 and most of those 5 to 7.9 occurred along the boundaries of the three active tectonics blocks. Researchers began exploration in this district in the 1960s and have used many methods such as wide-angle reflection and refraction seismic exploration, electrical prospecting, shallow seismic exploration, the gravity method, Global Positioning System （ GPS）, geodetic deformation survey,seismic array,and surveying and prospecting of active faults. Many valuable results have been obtained by using the various types of study methods. This paper summarizes the results of 40 years of such studies in this area by geoscientific researchers. The active block hypothesis states that strong earthquakes occur in such areas that the position wave velocity changes from high to low or the placement of the upper low-velocity body changes. Distribution of the geotem- perature field in this area shows that many strong earthquakes occur in the position of high temperature and anomalous temperature gradient. The differential movement of block interaction is very strong. The results of wide-angle reflection and refraction seismic exploration also indicate the occurrence of the upper Moho uplift phenomenon in the strong seismic focus,in which super- heated materials likely rise and melt rock as the hot mantle rock ascends in this area. By examining approximately 40 years of research in this area,including the deep seismic sounding profile, high gravity and magnetic anomalies, and inversion of seismic array data, we conclude that the Alashan and Erdos blocks are relatively stable and that the earthquake activity is weak, whereas the earthquake activity o

关 键 词：宁夏及邻区 活动构造块体 地壳结构 强震 

分 类 号：P315.24[天文地球—地震学]