地震衰减模型的研究进展

Research progress of seismic attenuation models

由于地下介质是非完全弹性的,地震波在地下传播过程中会出现衰减现象.为了正确模拟出该现象,国内外学者提出了许多切实可行的方法.本文通过调研大量的国内外相关文献,对描述衰减的模型进行了归纳总结,将其划分为两个主要类别:基于标准线性固体的近似常Q模型和分数阶常Q模型,并阐述了这两类模型进行波动方程正演模拟的基本原理、发展现状及优缺点,以及高时间精度和空间精度数值模拟技术的进展.在衰减模型中,分数阶常Q模型可以准确高效地描述某些频带内的地震波吸收衰减效应,并且能够解耦地震波传播过程中的振幅衰减和相位畸变.因此,本文对分数阶常Q模型进行了重点介绍,并基于此进行各向同性介质黏弹性波方程正演模拟,模拟冻土层中的地震波传播并分析冻土层对地震记录的影响.最后,对分数阶黏弹性波方程进行总结与展望.

As the underground medium is not completely elastic,seismic waves will experience attenuation during propagation.To accurately simulate this phenomenon,many feasible methods have been proposed by scholars at home and abroad.Through extensive research of domestic and foreign literatures,this paper summarizes and categorizes attenuation models into two main categories:approximate constant Q models based on standard linear solids models and fractional order constant Q models.It also elaborates on the basic principles,current developments,advantages,and disadvantages of these two models for wave equation forward modeling,as well as the progress of high-precision time and space numerical simulation techniques.Among these attenuation models,the fractional order constant Q model can accurately and efficiently describe the absorption and attenuation effects of seismic waves in certain frequency bands,and can decouple the amplitude attenuation and phase distortion during the propagation of seismic waves.Therefore,this paper focuses on the introduction of the fractional-order constant-Q model,and based on this,conducts forward simulation of isotropic viscoelastic wave equation in homogeneous media.It also simulates the propagation of seismic waves in frozen soil layers and analyzes the influence of frozen soil layers on seismic records.Finally,a summary and outlook are provided for the fractional-order viscoelastic wave equation.