Abstract: In this paper,we calculate receiver functions of body wave under the 14 stations in Shaanxi Province from 3-component digital waveform data of teleseismic earthquake events and obtain the thickness and Poisson ratio in crust of this area through H-kappa stacking.Through analysing the characteristics of crustal structure in Shaanxi Province,we discuss the relationship between seismic activity,crustal structure and geological structure in Shaanxi Province.The results show that(1)Crustal thickness in western Shaanxi is thicker than that in the east.Crustal thickness in the south and north of Shaanxi(≥40km)is larger than that in Weihe Basin,middle Shaanxi(about 34～40km).Among 14 stations,the crust beneath Huayin station is the thinnest(34km),which locates on the boundary between eastern Weihe Basin and Shanxi Province,and the biggest thickness(48km)appears beneath Longxian station at the northwestern end of Weihe Basin.(2)Poisson ratio in Shaanxi Province is about 0.24～0.29,which may be related to rock compositions.Poisson ratio in the north of Weihe Basin has higher values than those in the south.(3)There exist some relations between seismic activity and geological structure.The Weihe Basin with frequent earthquakes locates in a compound position of several tectonic systems.The Hanzhong Basin and Ankang Basin in the south of Shaanxi are controlled by several major faults,where the seismicity is relatively low.Seismic activity in northern Shaanxi is the lowest because of stable geological structure.Poisson ratio reflects material composition of earth interior.Our analysis suggests that seismic activity in the region with high Poisson ratio is higher than that with low Poisson ratio.

Key words: receiver function, crustal structure, seismic activity, Shaanxi

摘要： 文中利用陕西数字地震遥测台网14个遥测子台记录的远震波形资料,用频率域反褶积方法提取接收函数,由H-Kappa叠加方法反演得到各台站下方的地壳厚度和泊松比。在此基础上结合相关地震构造文献,对陕西地区的地壳特征进行了分析,并讨论了陕西地震活动与地壳结构、地质构造之间的关系。研究结果表明:1)陕西地区的地壳总体趋势是东薄西厚,陕西南部和北部地区地壳较厚(≥40km),位于陕西中部的渭河盆地地壳较薄(34～40km);14个台站中,渭河盆地东部与山西交界的华阴台下方地壳厚度最薄(34km),而盆地西北端的陇县台位于六盘山余脉上,地壳厚度最厚(48km)。2)陕西地区泊松比值总体变化不大(0.24～0.29),可能表明这一地区的岩石组成以中度组分为主;以渭河盆地为界,向北靠近地台一侧泊松比值相对较高,向南靠近秦岭山脉一侧则比值相对较低。3)地震活动与地质构造之间存在内在的联系。渭河盆地处于几个构造体系的复合部位,属于强地震的多发区;陕西南部地区的地震活动相对较弱,主要发生在汉中盆地和安康盆地,受陕南几条主要断裂控制;陕西北部地区地质构造相对稳定,地震活动最弱。泊松比反映了地球内部的物质构成,分析认为其与地震活动存在一定的关系,即泊松比较高区域的地震活动性要高于较低的区域。

关键词: 接收函数, 地壳结构, 地震活动, 陕西