渭河断陷盆地及邻近地区地震活动的深部背景  

Seismicity and deep backgrounds of the Weihe fault depression and its adjacent areas

作　　者：王卫东[1] 张永志[1] 王平[2] 杜长娥[2] 

机构地区：[1]长安大学地质工程与测绘工程学院,陕西西安710054 [2]陕西省地震局,陕西西安710068

出　　处：《地球科学与环境学报》2004年第3期57-60,共4页Journal of Earth Sciences and Environment

基　　金：陕西省科学技术委员会项目(95K12G9);陕西省地震局九五项目

摘　　要：　利用西安数字地震遥测台网记录的数字地震资料,采用P初动半周期方法,得到了渭河断陷盆地及邻近地区的Q值分布,探讨了该区域地震活动性与地壳内速度分布、Q值分布及地质构造的关系。结果表明:①Q值分布有两个地区存在较强烈地横向不均匀性,其一是淳化、耀县高Q值区和相邻的西安、富平低Q值区,其二是陕晋交界处的韩城高Q值区和相邻的澄城低Q值区,它们都位于不同构造单元交界、差异运动显著、新老地层交错的地区;②历史强震震中主要分布在Q值分布高、低值间的过渡带上;③Q值分布与20km深度P波速度分布有较好地一致性。上述结果表明,该区域的地震活动性有深部构造背景,与区域速度场、介质品质因子分布密切相关。In this paper,by using the seismic data recorded from Xi'an digital telemetry seismic network and the method of half period of first P arrivals ,Q value distribution of Weihe fault depression basin and its adjacent area is determined. The relationship between seismicity and Q value distribution, velocity distribution and geological structures in this region is then discussed. The results show that: (1) there are two strong lateral inhomogeneous regions of Q value distribution, one is Chunhua-Yaoxian region with high Q value and its adjacent Xi'an-Fuping region and Huaxian region with low Q value, the other is Hancheng region on the boundary between Shaanxi and Shanxi Provinces with high Q value and its adjacent Chengcheng region with low Q value. These two regions are located in a region where different tectonic units meet, and differential movement is significant and different rock strata are interceded;(2)the historical strong earthquakes occurred mainly in the transitional belt between the regions with high and low Q values; (3) the distribution of Q value is comparatively consistent with the image of P-wave velocity distribution at depth h=20 km in the studied area.The above results indicate that the seismicity in this region has deep geological background and is closely related to the distribution of Q value and the image of P-wave velocity distribution of the region.

关 键 词：地震活动 渭河断陷 速度分布 介质品质因子 

分 类 号：P315.2[天文地球—地震学] P315.5[天文地球—固体地球物理学]