Elastic Full Waveform Tomography (FWT) aims to reduce the misfit between recorded and modelled data, deduce a very detailed model of elastic material parameters in underground. The choice be inverted affects convergence quality reconstructed subsurface model. Using Cross-Triangle-Squares (CTS) three parametrizations, Lamé m1 = [λ, μ, ρ], seismic velocities m2 [Vp, Vs, ρ] impedances m3 [Ip, Is, for far-offset reflection acquisition geometries with explosive point sources free-surface...

We describe the application of rotated staggered‐grid (RSG) finite‐difference technique to wave equations for anisotropic and viscoelastic media. The RSG uses operators, leading a distribution modeling parameters in an elementary cell where all components one physical property are located only at single position. This can be advantageous propagation media or complex media, including high‐contrast discontinuities, because no averaging elastic moduli is needed. applied both displacement‐stress...

Heterogeneous finite-difference (FD) modeling assumes that the boundary conditions of elastic wavefield between material discontinuities are implicitly fulfilled by distribution parameters on numerical grid. It is widely applied to weak contrasts geologic formations inside earth. We test accuracy at free surface The for Rayleigh waves using conventional standard staggered-grid (SSG) and rotated staggered grid (RSG) investigated. tests reveal one cannot rely dispersion discretization...

Full-waveform inversion (FWI) of Rayleigh waves is attractive for shallow geotechnical investigations due to the high sensitivity S-wave velocity structure subsurface. In shallow-seismic field data, effects anelastic damping are significant. Dissipation results in a low-pass effect as well frequency-dependent decay with offset. We found this by comparing recorded waveforms elastic and viscoelastic wave simulation. The must be considered FWI waves. using simulation propagation failed...

The S-wave velocity of the shallow subsurface can be inferred from shallow-seismic Rayleigh waves. Traditionally, dispersion curves waves are inverted to obtain (local) as a function depth. Two-dimensional elastic full-waveform inversion (FWI) has potential also infer lateral variations. We have developed novel workflow for application 2D FWI recorded surface During preprocessing, we apply line-source simulation (spreading correction) and perform an priori estimation attenuation iterative...

Reliable models of in‐situ shear‐wave velocities shallow‐water marine sediments are important for geotechnical applications, lithological sediment characterization, and seismic exploration studies. We infer the 2D velocity structure from lateral variation Scholte‐wave dispersion. Scholte waves recorded in a common receiver gather generated by an air gun towed behind ship away single stationary ocean‐bottom seismometer. An offset window moves along to pick up local wavefield. A slant stack...

During the Quaternary, Rhine Glacier formed several overdeepened valleys, including Tannwald Basin (ICDP site 5068_1, Germany) about 45 km North of Lake Constance. These structures form sedimentary climate archives and thus help to understand dynamics in Alps.To obtain very high-resolution images sediment, seismic crosshole data was acquired using a high-frequency borehole source that predominantly generates SH-waves. The excited meter at 78 143 m depth, wavefield recorded depth 105 134 an...

We determine the 3-D in situ shear-wave velocities of shallow-water marine sediments by extending method surface wave tomography to Scholte-wave records acquired shallow waters. Scholte waves are excited air-gun shots water column and recorded at seafloor ocean-bottom seismometers as well buried geophones. Our new comprises three steps: (1) local phase-slowness values from slowness-frequency spectra calculated a wavefield transformation common-receiver gathers. Areal maps for each frequency...

Full waveform tomography (FWT) is a powerful velocity building method to exploit the full richness of seismic waveforms in complex media. Most applications today neglect frequency-dependent amplitude decrease and phase dispersion caused by intrinsic attenuation. In this study, we present numerical investigation influence attenuation on recovered model. Based generalized standard linear solid as rheological model, incorporate into 2-D time-domain acoustic FWT scheme. Attenuation considered...

ABSTRACT Three‐dimensional elastic full‐waveform inversion aims to reconstruct material properties of 3D structures in the subsurface with high resolution. Here we present an implementation based on adjoint‐state method. The code is optimized regarding runtime and storage costs by using a time‐frequency approach. gradient computed from monochromatic frequency‐domain particle‐velocity wavefields calculated time‐domain velocity‐stress finite‐difference scheme. was applied data complex random...

Ultrasonic echo testing is a more and frequently used technique in civil engineering to investigate concrete building elements, measure thickness as well locate characterise built-in components or inhomogeneities. Currently the Synthetic Aperture Focusing Technique (SAFT), which closely related Kirchhoff migration, most cases for imaging. However, this method known have difficulties image steeply dipping interfaces lower boundaries of tubes, voids similar objects. We transferred processing...

For safe tunnel excavation, it is important to predict lithologic and structural heterogeneities ahead of construction. Conventional seismic prediction systems utilize body waves (P- S-waves) that are directly generated at the walls or near cutter head boring machine (TBM). We propose a new strategy has been discovered by 3D elastic finite-difference (FD) modeling: Rayleigh arriving front face converted into high-amplitude S-waves propagating further ahead. Reflected backscattered back which...

ABSTRACT In order to keep up with the economic and safety demands of modern tunnel construction projects, especially in urban areas, there is a need detect threats real time while advancing. Tunnel prediction methods accompanying drilling process can help correlate update priori information on expected geological structures their actual spatial location or even existence ahead face. We recently presented seismic approach using surface waves, which has already proven its potential during...

Full-waveform inversion (FWI) of shallow-seismic surface waves is able to reconstruct lateral variations subsurface elastic properties. Line-source simulation for point-source data required when applying algorithms 2-D adjoint FWI recorded field data. The equivalent line-source response can be obtained by convolving the waveforms with |$\sqrt{t^{-1}}$| (t: traveltime), which produces a phase shift π/4. Subsequently an amplitude correction must applied. In this work we recommend scale...

Abstract In 2010 a reflection seismic survey was carried out on the Alpine glacier Colle Gnifetti. The processed and depth-converted data could be compared to nearby ice core, drilled almost bed. Comparisons showed that depth of P-wave bed too shallow, while SH-wave fitted ice-core length well. We are now able explain major part these differences using existing crystal orientations at calculate anisotropic velocities for P- SH-waves usually picked stacking compare them with zero-offset...

Full-waveform inversion (FWI) of surface waves can provide a valuable contribution to near-surface investigations, since they are mainly sensitive the S-wave velocity and hold high signal-to-noise ratio. We investigate performance individual 2-D elastic FWI Rayleigh Love as well feasibility simultaneous joint both wave types. apply these three methods synthetic data field data. In reconstruction tests we compare type inversions explore benefits inversion. perform similarly well, given that...

SUMMARY In near-surface surveys, shallow-seismic and ground-penetrating radar (GPR) full-waveform inversions (FWIs) have received increasing attention because of their ability to reconstruct high-resolution subsurface models. However, they different sensitivities the same targets thus may yield conflicting geophysical parameter To solve this issue, we developed an indirect joint petrophysical inversion (JPI) integrating multi-offset GPR data. These data are used porosity saturation whereby...

SUMMARY 2-D full-waveform inversion (FWI) of shallow-seismic wavefields has recently become a novel way to reconstruct S-wave velocity models the shallow subsurface with high vertical and lateral resolution. In most applications, seismic wave attenuation is ignored or considered as passive modelling parameter only. this study, we explore feasibility performance multiparameter viscoelastic FWI in which velocities P S waves, respectively, mass density are inverted simultaneously. Synthetic...

SUMMARY Full-waveform inversion (FWI) of ground-penetrating radar (GPR) data has received particular attention in the past decade because it can provide high-resolution subsurface models dielectric permittivity and electrical conductivity. In most GPR FWIs, these two parameters are regarded as frequency independent, which may lead to false estimates if they strongly depend on frequency, such shallow weathered zones. this study, we develop frequency-dependent FWI solve problem. Using τ-method...