基于远震接收函数计算三河—平谷地震区地壳厚度与泊松比

Calculation of crustal thickness and Poisson’s ratio in Sanhe-Pinggu earthquake area based on teleseismic receiver functions

利用防灾科技学院地震遥测台网2017年1月至2021年12月远震波形记录,通过H-κ叠加方法反演估算得到三河-平谷地震区下方莫霍面深度和地壳平均泊松比。结果表明:三河-平谷地震区莫霍面深度在31.7-41.1 km之间,起伏较大,整体向东下倾;研究区域泊松比变化存在横向不均匀性,泊松比介于0.240-0.303,平均值0.276 4,略高于全球大陆和中国内地地壳泊松比平均值。根据反演结果推测,三河-平谷地震区在华北地区地壳伸展背景下,受区域内断裂带影响,可能发生过岩浆底侵,幔源物质进入地壳,在造成莫霍面抬升的同时升高了泊松比。

Using the teleseismic waveform recorded by the Seismic Network of Institute of Disaster Prevention from January 2017 to December 2021,the Moho depth and average Poisson’s ratio of crust beneath the Sanhe-Pinggu earthquake area are inversed by the H-κstacking method.The results show that the Moho depth in the Sanhe-Pinggu earthquake area is between 31.7 and 41.1 km,with large fluctuations and downward tilt to the east as a whole.The variation of Poisson’s ratio in the area has lateral heterogeneity,ranging from 0.240-0.303,with an average value of 0.2764,slightly higher than the average value of Poisson’s ratio in the crust of the global continent and Chinese mainland.According to the inversion results,it can be inferred that under the background of crustal extension in North China,affected by the fault zone in the region,the Sanhe-Pinggu earthquake area may have experienced magmatic underplating,with mantle-derived materials entering the crust,which increased the Poisson’s ratio while raising the Moho surface.