We derive two sets of new wave equations involving the fractional time derivatives or Laplacians for simulating seismic propagation in viscoelastic anisotropic (VA) media based on Kjartansson's constant-Q model. The approximate Laplacian equation is developed under assumptions small velocity anisotropy parameter |$\delta$| and attenuation |${\delta _Q}$| (or weak anisotropy). Both formulas have advantages simple form can accurately describe (i.e. frequency-independent quality factor)...

Abstract Near-surface site characterization is of great significance in the fields geotechnical engineering and resource exploration. In this paper, we propose a near-surface method based on joint iterative analysis first-arrival surface-wave data (JIAFS). The proposed combines advantages traveltime tomography (FATT) multichannel surface waves (MASW). First, 1D S-wave velocity ( $$v_{{\text{S}}}$$ <mml:math...

SUMMARY Compared with surface waves, guided waves are rarely applied in near-surface investigation. The main reason may lie the complexity of their dispersion curves. Besides, study and understanding wave characteristics now also inadequate not deep enough. In this paper, we derived complete theoretical curves P–SV-wave pure P-wave systems layered media based on transmission matrix method obtained relative displacement amplitude coefficients at free as a function frequency phase velocity for...

Various surface-wave exploration methods have become increasingly important tools in investigating the properties of subsurface structures. Inversion experimental dispersion curves is generally an indispensable component these methods. Accurate and reliable calculation partial derivatives with respect to parameters layers critical success approaches if linearized inversion strategies are adopted. Here we present open-source MATLAB package, named SWPD (Surface Wave Partial Derivative), for...

Abstract In exploration and earthquake seismology, most sources used in subsurface structure imaging rock property estimation are fixed certain positions. Continuously moving seismic sources, such as vehicles the metro, one kind of important passive ambient noise research. Commonly, data acquisition processing for based on assumption simple point dispersion curve inversion is applied to constrain near-surface velocity. This workflow neglects Doppler effects. Considering continuously...

Summary The surface-wave modal inversion is generally the final step in various exploration methods. most widely used strategies are iterative-linear methods, which usually only invert S-wave velocities while keep other parameters, including thickness of each layer, as known a priori. Though easy implementation and fast computation, these make establishment an appropriate initial model time-consuming process, especially when priori information unavailable. We propose strategy that...

It is a convenient and effective way to infer near-surface S-wave velocity (VS) structures by using seismic surface waves. In spite of many successful applications on the geotechnical or engineering scale, surface-wave analysis inversion methods are still not widely used in oil exploration. Particularly, there few researches reported three-dimensional (3D) VS structure modelling with wave this exploration scale. paper, we proposed data processing scheme for 3D modelling, applied it field...

Accurate seismic wave simulation requires to consider the Earth's viscosity and anisotropy characteristics. In exploration, attenuation is generally assumed almost linear with frequency (therefore Q independent frequency). The Kjartansson's model can accurately describe constant-Q characteristics compared other approximate by superposition of elastic stokes mechanism. this study, we present a new viscoelastic anisotropic constitutive relation derive corresponding time-domain 2-D, 3-C...

Surface waves are widely used in the study of underground structures at various scales because their dispersion characteristics layered media. Whether natural seismology or engineering seismology, surface wave analysis methods have matured and developed for respective fields. However, oil gas exploration, many data processors still tend to consider as noise that needs be removed. To make more people pay attention application utilize carrying near information this paper takes processing LH...

Abstract The surface-wave analysis method is widely adopted to build a near-surface shear-wave velocity structure. Reliable dispersion imaging results form the basis for subsequent picking and inversion of curves. In this paper, we present high-resolution (CSFK) seismic surface waves based on chirplet transform (CT). CT introduces concept chirp rate, which could focus energy well in time-frequency domain. First, each trace time-distance domain transformed by CT. Thus, common frequency...

Automatic picking of seismic velocity can be performed using k-means clustering. In simple clustering, the number clusters needs to predetermined, while result is affected by initial value each cluster center. this study, we present an unsupervised weighted clustering velocity-picking method that picks centers energy instead geometric clusters. This works on semblance spectrum and requires function three user-defined thresholds limit search area. The their times are obtained according a...

The staggered grid finite difference (SGFD) method has been widely utilised in seismic forward modelling. accuracy of modelling results a great influence on the subsequent imaging and inversion. Numerical dispersion is one inherent problems SGFD method. To suppress dispersion, we here introduce truncated window function method, which can get optimised operators after truncating spatial convolution series pseudo-spectral empirical criteria functions are main lobe width that should be as...

ABSTRACT In recent years, surface‐wave analysis method has been developed rapidly in many fields. Multichannel of surface waves can provide near‐surface one‐dimensional shear‐wave velocity profiles. Because linearized inversion dispersion curves relies heavily on the choice initial model, setting an inappropriate model lead to poor results, or even failure inversion. However, it is difficult establish a reasonable without priori information, which unavailable most cases. To cope with this...

Summary In petroleum exploration, Rayleigh waves, the primary kind of surface are often removed as noise. While in engineering however, dispersion characteristics waves have been used to invert near parameters since 1960s. And widely-used multichannel analysis wave (MASW) method is a typical approach estimate S-wave velocity and quality factor by extracting curves. Two horizontally-layered media models established this paper order study applicability MASW exploration. High precision...

Summary Love waves is dispersion surface that result from multiple reflections of SH waves. The characteristic independent P-wave velocity, in other words, a function frequency and just three earth properties: S-wave density, thickness layer. This merit can be used near velocity inversion to get more reliable than Rayleigh In this study, we deduced the SH-wave staggered grid finite difference schemes with ADE CFS-PML absorbing boundary condition research propagation characteristics...

本文基于Kjartansson常 Q 模型理论，推导了常 衰减介质中黏声波和黏弹性波的速度-应力方程，并采用基于二项式窗函数的优化交错网格有限差分方法进行了数值模拟，同时引入不分裂的复频移卷积完全匹配层(CPML)吸收边界条件，以消除边界反射.使用基于自适应时间步长记忆方法的中心差分近似时间分数阶导数，与常用的短时记忆方法相比，提高了波动方程的离散化精度和计算效率.通过对比均匀模型下声波的数值解与解析解，验证了算法的精确性，并进一步分析了不同品质因子下地震波的频散及衰减特征.对BP盐丘模型的数值模拟结果可以较好地反映本文数值方法对复杂介质的适应性及频散压制效果.

The coefficients of traditional variable staggered grid (VSG) finite difference are obtained by Taylor-series expansion (TE). However, the numerical dispersion is serious in large wave number range. We propose a combined optimal coefficient (CODC) method based on combining TE and sampling approximation for VSG modeling, which could effectively suppress dispersion. Dispersion analyses shows that CODC can satisfy relation larger Finally, example demonstrates improve accuracy simulation...

At present, various main and passive sources Rayleigh wave exploration methods are developing rapidly play an increasingly important role in near surface exploration. dispersion curve is the key point to obtain a reliable near-surface S-wave velocity profile. As with many other geophysical inversion problems, problem highly nonlinear global optimization problem. In order alleviate risk of falling into local optimal solution, this paper first introduces emerging search methods, shuffle...

The inversion of surface wave dispersion curves could provide near-surface 1D shear-wave velocity (VS) profiles. However, linearized methods depend heavily on the choice initial models. A multiscale method is devised for (MS-SWI). key idea MS-SWI introduction mergence and division processes layers. Through entire inversion, this operation makes inverted subsurface model automatically optimized at different scales, finally we obtain reasonable layered model. MSSWI reduces difficulty setting...