利用接收函数研究河北及邻区地壳厚度与泊松比分布特征

Crustal Thickness and Poisson's Ratio of Hebei and Adjacent Areas from Teleseisimic Receiver Functions

本文收集了河北及邻区174个宽频带地震仪2007年1月至2011年12月记录到的全球范围内体波震级6.0以上、共488个远震波形资料。利用H-k叠加搜索方法得到河北及邻区143个台站下方接收函数、地壳厚度和泊松比值分布特征。结果表明,河北及邻区地壳厚度具有明显的分块特征并与区域构造背景有较好的相关性,泊松比值在0.25上下变化,与全球的泊松比估计值相当。河北及邻区地壳厚度以太行山山脉为界呈现出东薄西厚的特征并与地表地形起伏呈正相关;山西地震带南北地壳厚度存在明显差异,大同、宁武及安泽盆地地区泊松比值超过0.3;张—渤地震带的地壳厚度自东向西逐渐增厚,泊松比值则表现为相对较强的横向变化。华北平原带的薄地壳和低泊松比值特征可能与华北克拉通拆沉作用相关联。

We collect waveforms of teleseismic events which occurred from January 2007 to October 2011 from 174 broadband seismic stations deployed in Hebei province and adjacent areas and use H-k stacking method to calculate the average crustal thickness and Poisson＇s ratios in the study area. In order to obtain reliable receiver functions, the broadband seismograms of 488 teleseismic earthquakes occurred in the epicentral distance range from 30 degree to 90 degree with magnitudes larger than Mb6.0 were collected. The results show that the crustal thickness exhibit conspicuous lateral heterogeneity and correlate well to the regional geological？ tectonic features. Poissoffs ratio is equated with global model＇s es timates which fluctuate at about 0.25. Crustal thickness correlates positively to the topography and the Taihang mountain range is the transition zone of thick and thin crustal thickness. Crustal thickness in the north and south of Shanxi Earthquake Zone exists obvious difference and Poisson＇s ratios in Tatong, Ningwu and Anze basins are greater than 0.3. Crustal thickness in the Zhangbo Earthquake Zone decreases from west to north and its Poisson＇s ratio has conspicuous lateral heterogeneity. The Huabei basin＇s thin crust and low Poisson＇s ratio may correlate with the North China craton delamination.