基于远震P波接收函数研究江苏地区地壳厚度和泊松比

Crustal Thickness and Ratio of Poisson in Jiangsu Areaby Teleseismic Receiver Function

根据江苏数字地震台网32个宽频带地震台站记录的远震波形资料,使用时间域反褶积的方法提取P波接收函数,由H-K叠加搜索方法反演得到各台站下方的地壳厚度和泊松比。结果表明:①江苏地区地壳厚度整体呈现自东向西增厚趋势,具有明显的空间分布特征,与该区地质构造背景有较好的对应。主要表现为:苏鲁造山带地区地壳厚度高于其周边地区;华北板块的地壳厚度变化比较平缓,主要为32~33 km;下扬子板块地区的地壳厚度变化较大,为27~34 km,位于该区中东部大陆边缘地区的台站下方平均地壳厚度约为28 km。②研究区泊松比为0.22~0.28,受高压和超高压变质岩带影响,苏鲁造山带及周边地区的泊松比较高;下扬子板块的茅东断裂及周边地区的泊松比变化明显,呈高低相间分布,且泊松比高值区及变化明显区与地震活动性具有一定的关系。

In this paper,we calculate P-wave receiver functions by time domain deconvolution method under the 32 stations in Jiangsu Province from three component digital waveform data of teleseismic earthquake events and obtain the thickness and average poisson s ratio in the crust of this area by H-K stacking.The results show that:①The crustal thickness in Jiangsu area has a thickening trend from east to west and obvious spatial distribution characteristics,which has a good correspondence with the geological tectonic setting,The first one is the crustal thickness in the Sulu orogenic belt area is higher than that in the surrounding area;the second one is the crustal thickness in the North China plate is relatively flat,mainly between 32 km and 33 km;and the last one is the crustal thickness in the Lower Yangtze plate area varies greatly between 27 km and 34 km and the average crust thickness in the central and eastern continental margins of this area is about 28 km.②The poisson s ratio in the study area is between 0.22 and 0.28.Because of the high-pressure and ultra-high-pressure metamorphic rocks,the poisson s ratio located below the Sulu orogenic belt and the surrounding area is higher.The poisson s ratio changes significantly and shows a high and low phase distribution in the Maodong fault and its surrounding area which is located in the lower Yangtze block,and the higher poisson s ratio area and the changing poisson s ratio area have a certain relationship with the seismic activity.