利用接收函数频率特征研究莫霍面形态及应用  

Constraining Moho characteristics with frequency-dependence of receiver function and its application

作　　者：宋婷 沈旭章 梅秀苹[1] Song Ting;Shen Xuzhang;Mei Xiuping(Lanzhou Institute of Seismology,China Earthquake Administration,Lanzhou 730000,China;School of Earth Sciences and Engineering,Sun Yat-Sen University,Guangzhou 510275,China)

机构地区：[1]中国地震局兰州地震研究所,中国兰州730000 [2]中山大学地球科学与工程学院,中国广州510275

出　　处：《地震学报》2020年第2期135-150,I0001,共17页Acta Seismologica Sinica

基　　金：国家自然科学基金(41704057,41730212和41874052);国家重点研发计划(2017YFC1500103);甘肃省地震局科技发展基金(2019Q06)联合资助。

摘　　要：基于不同莫霍面模型的全波形理论地震图,计算了不同频率的接收函数,分析对比了不同形态莫霍面在不同频率上的接收函数变化特征。数值试验结果显示,当莫霍面的形态复杂时,高频接收函数上P-S转换波和多次波会出现多峰值特征。之后对不同形态莫霍面的模型在不同频率的接收函数进行了分类总结,据此判别实际观测资料所表征的莫霍面性质。以位于青藏高原东北缘的高台(GTA)地震台为例,分析了该台站不同频率的接收函数。结果表明,该台站下方莫霍面总体为遵循同一变化规律的速度过渡带,但在沿龙首山断裂方向附近速度变化不同于主要变化方式。基于此,通过对观测结构进行拟合构建了该台站下方地壳及莫霍面模型,并结合地质学和岩石学等方面的结果对这种莫霍面形成的原因进行了探讨,进而推断此种莫霍面是由于多种构造因素以及上地幔热物质上涌引起地区壳幔物质的分异与交换所导致。Based on the full-waveform theoretical seismograms of different Moho velocity models,the receiver functions of different frequencies are calculated,and the performances of different Moho morphologies on receiver functions at different frequencies are analyzed and compared.The numerical results show that when the Moho is complex,the P-S converted wave and the multiple wave will have multi-peak characteristics on the high-frequency receiver functions.Receiver functions of different frequencies based on different Moho velocity models are classified and summarized,and the Moho properties revealed by the actual observation data can be discriminated.Taking the seismic station Gaotai(GTA)in the northeastern margin of Tibetan Plateau as an example,this paper analyzed the effects of the receiver functions of different frequencies on the Moho morphology beneath the station.The results show that Moho beneath the station is a velocity transitional zone in which velocity varies in a dominant regular,except for the velocity varies at the azimuth along the Longshoushan fault.Furthermore,we built the Moho velocity model beneath the station by fitting the observation structure.Combining the results of geology and petrology,the causes of this Moho morphology were discussed.It is inferred that various tectonic factors and the upwelling and bottom invasion of the upper mantle thermal materials give rise to the differentiation and exchange of crust-mantle materials in this area,and then the Moho morphology mentioned above is resulted in.

关 键 词：接收函数 频率 莫霍面形态 速度模型 

分 类 号：P315.31[天文地球—地震学]