波场梯度法研究进展

Recent progress on wave gradiometry method

波场梯度法是一种基于密集台阵记录的地震波形的地震数据处理方法,适用于多种地震信号/震相,比如P波、S波、Rayleigh波、Love波和环境噪声等.由于充分考虑了波场的时空变化,可以获得更多的地震波传播参数或介质参数,比如应力、旋度、地震波速度、方位角、几何扩散、辐射模式、方位各向异性和Q值等.自2007年波场梯度法的原理提出以来,该方法在河湾河谷的强地面运动研究、断层探测、月壳浅层结构成像、地球浅地表或地壳地幔速度结构和方位各向异性反演等方面得到较好的应用.基于不同的信号处理方法,波场梯度法也发展出不同的研究分支,比如基于傅里叶变换、小波变换或希尔伯特变换的波场梯度研究;基于不同参考坐标系、不同台网类型或不同震相/信号源也可以将波场梯度法划分为不同的研究方向.本文主要从方法原理、研究进展和方法比较对波场梯度法进行详细地描述,同时对其发展趋势进行简单地讨论.

Wave gradiometry method is a data processing technique based on dense seismic arrays and is suitable for a variety of seismic signals/phases such as P-waves,S-waves,Rayleigh waves,Love waves,and ambient noise.Since both temporal and spatial differences within the wave field are fully considered by this method,more seismic wave propagation parameters and medium physical properties can be obtained;these include stress,rotation,seismic velocity,azimuth,geometrical spreading,radiation pattern,azimuthal anisotropy,and Q value.Since its introduction in 2007,wave gradiometry has been widely used to study strong ground motion in river valleys,shallow lunar crust,fault systems and the inversions of the velocity and anisotropy models of shallow Earth,crust,or mantle.Based on different signal processing techniques,wave gradiometry method has been developed into different branches such as the wave gradiometry analyses based on Fourier transform,wavelet transform and Hilbert transform.These methods have branched into further research based on different reference coordinate systems,network types,or seismic phases/signal sources.In this paper,the methodology,recent progress,developmental trend,and method comparisons of wave gradiometry are described in detail.