【摘要】 利用71个远震的波形资料,用接收函数方法提取了布设在长白山—镜泊湖火山区的34个宽频带流动数字地震台站的接收函数,通过对接收函数反演,获得了台站下方的S波速度结构.研究结果表明,沈阳—敦化一线莫霍面深度32～33km ,向西地壳厚度加厚,到长春附近地壳厚度约为36km .在天池火山口莫霍面深度为达38km ,而镜泊湖火山口森林的莫霍面深度约为39km .总体看研究区的地壳厚度是南浅北深.长白山天池火山口附近地下10km左右有一明显的低速层存在;镜泊湖火山口森林附近30km也可能有低速体存在;研究发现莫霍面上S波速度梯度在火山口附近和远离火山口有明显区别.在火山口附近其莫霍面的S波速度梯度比非火山口地区的S波速度梯度明显小,说明火山口下与一般的地壳莫霍面结构有差别.研究发现沈阳—敦化一线两侧的莫霍面深度有较大变化,其位置与地表的敦化—密山断裂基本一致,说明敦化—密山断裂是研究区的一条非常重要的地质构造带.更多还原

【Abstract】 We have obtained 34 receiver functions from 71 teleseismic waveforms recorded by 34 stations that were installed in Changbaishan-Jingpohu volcanic area. Through inversing receiver function of 34 seismic stations, we obtain S wave velocity structures beneath the stations. The results revealed that the Moho depth is about 32～33km along Shenyang-Dunhua direction and becomes deeper toward its west side. In Changchun area, the Moho thickness reaches about 36km,and under the crater of Changbai-Tianchi volcano the depth of Moho reaches about 38km, while beneath Jinpohu volcanic area, Moho depth is about 39km. Overall, the crust of studied area is thick in north and thin in south. We found an anomalous layer with obvious low S wave velocity beneath Changbai-Tianchi crater at about 10km depth. Beneath Jingpohu volcanic area there is also possibly a low S-wave velocity anomalous body at about 30km depth. The results show that the S-wave velocity gradients at Moho are obviously different near and far from the crater. The gradient near crater is clearly smaller than that in areas without volcano, which suggests that Moho structures beneath volcano are different from general Moho structures in other areas. The crust thickness at two sides of Shenyang-Dunhua direction has a comparatively great change and its location is almost same as Dunhua-Mishan fault at near surface. Therefore, Dunha-Mishan fault is a very important geological structure zone in the studied area.更多还原