基于热重力改正的接收函数与重力联合估计技术及福建地区的应用  

Joint estimation by receiver function and gravity data based on thermal gravity correction and its application in Fujian province,China

作　　者：唐晗晗 郭良辉 李永华[4,5] TANG HanHan;GUO LiangHui;LI YongHua(Key Laboratory of Intraplate Volcanoes and Earthquakes(China University of Geosciences,Beijing),Ministry of Education,Beijing 100083,China;Chinese Academy of Geological Sciences,Beijing 100037,China;State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences,Beijing 100083,China;Institute of Geophysics,China Earthquake Administration,Beijing 100081,China;Key Laboratory of Earthquake Source Physics,China Earthquake Administration,Beijing 100081,China)

机构地区：[1]陆内火山与地震教育部重点实验室(中国地质大学,北京),北京100083 [2]中国地质科学院,北京100037 [3]地质过程与矿产资源国家重点实验室(中国地质大学),北京100083 [4]中国地震局地球物理研究所,北京100081 [5]中国地震局震源物理重点实验室,北京100081

出　　处：《地球物理学报》2024年第7期2668-2682,共15页Chinese Journal of Geophysics

基　　金：国家自然科学基金项目(41974101,U1839210,41874097,41774098)联合资助。

摘　　要：接收函数与重力联合估计技术是获取台站下方地壳厚度和波速比参数的一种有效手段,重力数据的引入可改善传统接收函数H-κ叠加法在壳内多次波信号不清晰时估计不准的问题.在大地热流较高的地区,热重力扰动成为布格重力异常的不可忽略的重要组成部分,此时常规接收函数与重力联合估计技术并不适用.本文给出基于热重力改正的接收函数与重力联合估计技术,通过热重力改正削弱热异常对重力数据的影响,同时采用接收函数Ps震相与重力数据的联合约束算法,避免多次波不清晰而引入误差的问题,实现高热流背景地区地壳厚度和波速比的有效估计.模型测试验证了本文技术的有效性和稳健性,给出了启动热重力改正的阈值(-10 mGal).典型高热流背景的福建地区实际数据应用结果表明,福建地区地壳向沿海地区减薄(约28 km),闽西和闽东南地区泊松比偏高(>0.26),暗示其下方存在地壳减薄的同时伴随着幔源物质的底侵.The joint estimation by receiver function and gravity data is an effective method to obtain crustal thickness and VP/VS ratio beneath the seismic station.The introduction of gravity data could improve estimation accuracy compare to the traditional receiver function H-κstacking method,especially in the case of unclear crustal multiple waves.In areas of high geothermal,thermal gravity disturbance is an important component of the Bouguer gravity anomaly so that it cannot be neglected.At this point,the traditional joint estimation by receiver function and gravity data is no longer applicable.In this paper,an improved joint estimation based on thermal gravity correction is proposed to weaken the effect of thermal gravity disturbance.Furthermore,we combine Ps phase of receiver functions with gravity data to avoid errors introduced by unclear multiples.These improvements enable us to accurately estimate the crustal structure in the area of high geothermal.Synthetic tests verified the feasibility and robustness of this techniques,and provided the threshold of-10 mGal for initiating thermal gravity correction.The real data application in Fujian province,a typical area with high heat flow background,reveals that the crust thins toward coast area(about 28 km).High crustal Poisson's ratios(>0.26)in western and southeastern Fujian indicate that crust thinning may be accompanied by underplating from mantle materials.

关 键 词：热重力 接收函数与重力联合估计 福建地区 地壳厚度 波速比 

分 类 号：P315[天文地球—地震学]