【摘要】 泊松比是了解地球内部介质的一个重要参数,在地震学上可以通过P波和S波速度的比值来确定.但是传统人工地震测深采用的炸药等爆破源产生的S波较弱,难以用来研究泊松比结构.对2006年河北省遵化市上关湖水库大容量气枪试验产生的地震数据进行研究,发现气枪震源能够有效地产生S波.根据偏振分析,认为S波主要是气枪产生的P波在水库底部固液界面转换产生的.波形拟合能够充分利用波形和走时信息,是研究地下结构的一种有效的方法.对气枪产生的S波进行波形拟合,获得了燕山隆起带南部地区地壳的S波速度模型,并对比修正后的P波速度模型,进一步得到了该地区的泊松比结构.研究表明:1)该地区的地壳厚度约为33km.2)该地区地壳整体泊松比值偏低,上(0～14km)中(14～28km)下(28～33km)地壳以及上地幔顶部(33km附近)的泊松比平均值分别为0.25,0.25,0.27,0.27.上地壳和中地壳可能以长英质的酸性岩石为主,下地壳和上地幔顶部可能以铁镁质的基性岩石和中性岩石为主.3)该地区上下地壳各存在一个低速层,它们可能主要是流体作用的结果.更多还原

【Abstract】 The Poisson’s ratio,an important parameter to understand the interior of the earth,can be determined uniquely from the ratio of P to S seismic wave velocity.But traditional seismic sources used in deep seismic sounding such as dynamite can not generate high energy S waves.We analysis the seismic data generated by airgun experiments taken in Shangguan water reservoir in 2006,find that,airguns in a water reservoir can generate high energy S waves,and the S waves are converted waves at the water-solid interface from P waves generated by the airgun source.The one-dimensional Poisson’s ratio model of southern Yanshan uplift were got from S and P wave velocity models,which were derived by comparison of calculated synthetic seismograms with the recorded seismic data generated by airguns in Shangguan water reservoir.Our research indicate that: 1) The crustal thickness of the study area is 33 km.2) Poisson’s ratio of the crust in the study area is lower than the average of the global.Poisson’s ratio in the upper crust(0~14 km),middle crust(14~28 km),lower crust(28~33 km) and upper mantle(about 33 km) is 0.25,0.25,0.27,0.27,indicate that the composition of the upper and middle crust is felsic rocks,the composition of the lower crust and the upper mantle are mafic and intermediate rocks.3) The low velocity zones mainly caused by fluid both exist in the upper and lower crust in the study area.更多还原