依舒断裂带北段莫霍面特征与泊松比

Moho characteristics and Poisson’s ratio in the northern segment of the Yishu fault zone

伊舒断裂带北段是黑龙江省地震跟踪监测重点区域之一,具有较强的地震活动性,为主要历史强震发生区域。利用该区域4个固定地震台记录到的远震地震事件资料,采用频率域反褶积方法,提取远震P波接收函数,再利用H—κ叠加方法计算台站下方莫霍面深度和泊松比。结果表明:受太平洋板块俯冲作用的影响,块体间相互挤压,双鸭山地震台下方莫霍面发生了错断,并且一侧莫霍面叠置在另外一侧上方,鹤岗地震台西侧莫霍面上方存在1个速度间断面;区域内泊松比值较高,为0.266—0.277,反映了上地幔铁镁物质上涌到下地壳中。

The northern segment of the Yishu fault zone is one of the key areas of earthquake monitoring in Heilongjiang Province.It has strong seismicity and is the main historical strong earthquake occurrence area.In this paper,P-wave receiver functions are computed from seismograms of teleseismic events recorded at four fixed seismic stations in the area using the frequency domain deconvolution method,and then the Moho depth and Poisson’s ratio are calculated by the H-kappa superposition method.Results show dislocation and superposition of the Moho beneath the Shuangyashan Seismic Station,and there is a velocity discontinuity above the Moho in the west of Hegang station;Poisson’s ratio ranges from 0.266 to 0.277 in the study area,which reflects the upwelling of iron and magnesium materials from the upper mantle into the lower crust.