Three-dimensional imaging of shear wave velocity in the uppermost 30 m of the soil column in Anchorage, Alaska

Badal, José; Dutta, Utpal; Serón, Francisco J.; Biswas, N. N.

doi:10.1111/j.1365-246x.2004.02327.x

Cited by 16 publications

(12 citation statements)

References 32 publications

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“…The procedure results in the generation of three-dimensional models and velocity distribution in various slices. This interpolation has earlier been applied with success to large regions like the Iberian Peninsula (Badal et al, 1996;Corchete et al, 1995), but also to small zones (Badal et al, 2000;Chourak et al, 2001Chourak et al, , 2003Badal et al, 2004). The method can adequately extract the highly heterogeneous, near-surface structure.…”

Section: -D Visualizationmentioning

confidence: 94%

“…The theoretical development of the method and the flowchart of the algorithm can be found in Corchete et al (1995), Sabadell et al (1997) and Sero´n et al (1999). Recently Sero´n et al (2001) and Badal et al (2004) have given brief descriptions of the mathematical content of the method and details on its implementation. Although the method is fairly general and applicable to any class of mapping, we shall restrict our treatment to structured grids, i.e.…”

Section: -D Visualizationmentioning

confidence: 98%

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Shallow Seismic Velocity Structure of the Betic Cordillera (Southern Spain) from Modelling of Rayleigh Wave Dispersion

et al. 2005

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A detailed dispersion analysis of Rayleigh waves generated by local earthquakes and occasionally by blasts that occurred in southern Spain, was undertaken to obtain the shear-wave velocity structure of the region at shallow depth. Our database includes seismograms generated by 35 seismic events that were recorded by 15 single-component short-period stations from 1990 to 1995. All these events have focal depths less than 10 km and body-wave magnitudes between 3.0 and 4.0, and they were all recorded at distances between 40 and 300 km from the epicentre. We analysed a total of 90 source-station Rayleigh-wave paths. The collected data were processed by standard digital filtering techniques to obtain Rayleigh-wave group-velocity dispersion measurements. The path-averaged group velocities vary from 1.12 to 2.25 km/s within the 1.0-6.0 s period interval. Then, using a stochastic inversion approach we obtained 1-D shearwave velocity-depth models across the study area, which were resolved to a depth of circa 5 km. The inverted shear-wave velocities range approximately between 1.0 and 3.8 km/s with a standard deviation range of 0.05-0.16 km/s, and show significant variations from region to region. These results were combined to produce 3-D images via volumetric modelling and data visualization. We present images that show different shear velocity patterns for the Betic Cordillera. Looking at the velocity distribution at various depths and at vertical sections, we discuss of the study area in terms of subsurface structure and S-wave velocity distribution (low velocity channels, basement depth, etc.) at very shallow depths (0-5 km). Our results characterize the region sufficiently and lead to a correlation of shear-wave velocity with the different geological units features.

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Section: -D Visualizationmentioning

confidence: 94%

Section: -D Visualizationmentioning

confidence: 98%

Shallow Seismic Velocity Structure of the Betic Cordillera (Southern Spain) from Modelling of Rayleigh Wave Dispersion

et al. 2005

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“…This coupling method disappears if the near‐surface shear wave speed ( V S ) drops below the atmospheric sound speed (Figure 6). Near‐surface V S below that of the speed of sound in air are not uncommon and are often found in regions where the primary surface cover is composed of loose or unconsolidated soil [e.g., Nunziata et al , 2004; Badal et al , 2004; Kanli et al , 2006]. This suggests that the overall paucity of observations of precursory Rayleigh waves may stem from a general prevalence of unconsolidated overburden in the near surface.…”

Section: Precursory Seismic Wavesmentioning

confidence: 99%

Seismic observations of meteors: Coupling theory and observations

Edwards

Eaton

Brown

2008

Reviews of Geophysics

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[1] Over the last century, seismic instruments have recorded, with increasing frequency, the ground motion produced by meteorically generated shock waves striking the Earth's surface. In this review, the history of meteorrelated seismic signals is discussed, along with documented waveform characteristics, source mechanisms, air-ground coupling phenomena, and kinematic methods of determining meteor trajectories and event locations. Uncertainties in the mechanics of air-ground coupling, however, have left methods of measuring meteor source energy underdeveloped.To date, coupling of acoustic waves directly with the Earth's surface represents the bulk of the observed meteor-related seismic signals, while precursory and impact-related seismic waves remain an observational rarity. With proliferation of infrasound and seismic monitoring systems, new opportunities exist to explore the relationship between Earth's atmosphere and surface. Continued study of meteor seismology will lead to new methods to constrain energies, sizes, and fluxes for moderately (cm to m) sized meteoroids on Earth and potentially on Mars.

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“…), earthquake location (Kennett and Engdahl ; Piromallo and Morelli ), and seismic tomography (Morelli and Dziewonski ; Hole ; Badal et al . ; Rawlinson and Sambridge ; Taillandier et al . ; Huang and Bellefleur ).…”

Section: Introductionmentioning

confidence: 99%

An upwind fast sweeping scheme for calculating seismic wave first‐arrival travel times for models with an irregular free surface

Lan

Chen

2017

Geophysical Prospecting

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The topography‐dependent eikonal equation formulated in a curvilinear coordinate system has recently been established and revealed as being effective in calculating first‐arrival travel times of seismic waves in an Earth model with an irregular free surface. The Lax–Friedrichs sweeping scheme, widely used in previous studies as for approximating the topography‐dependent eikonal equation viscosity solutions, is more dissipative and needs a much higher number of iterations to converge. Furthermore, the required number of iterations grows with the grid refinement and results in heavy computation in dense grids, which hampers the application of the Lax–Friedrichs sweeping scheme to seismic wave travel‐time calculation and high‐resolution imaging. In this paper, we introduce a new upwind fast sweeping solver by discretising the Legendre transform of the numerical Hamiltonian of the topography‐dependent eikonal equation using an explicit formula. The minimisation related to the Legendre transform in the sweeping scheme is solved analytically, which proved to be much more efficient than the Lax–Friedrichs algorithm in solving the topography‐dependent eikonal equation. Several numerical experiments demonstrate that the new upwind fast sweeping method converges and achieves much better accuracy after a finite number of iterations, independently of the mesh size, which makes it an efficient and robust tool for calculating travel times in the presence of a non‐flat free surface.

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Three-dimensional imaging of shear wave velocity in the uppermost 30 m of the soil column in Anchorage, Alaska

Cited by 16 publications

References 32 publications

Shallow Seismic Velocity Structure of the Betic Cordillera (Southern Spain) from Modelling of Rayleigh Wave Dispersion

Shallow Seismic Velocity Structure of the Betic Cordillera (Southern Spain) from Modelling of Rayleigh Wave Dispersion

Seismic observations of meteors: Coupling theory and observations

An upwind fast sweeping scheme for calculating seismic wave first‐arrival travel times for models with an irregular free surface

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