Dynamic smoothing in cross‐well tomography

Németh, Tamás; Qin, Fuhao; Nørmark, Egon

doi:10.1190/1.1822331

Cited by 8 publications

(11 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Plotting travel time reciprocity to determine if the first arrival time from shot A to receiver B equals that from shot B to receiver A, helped to identify mispicked first arrivals that were subsequently repicked to minimize errors. A two‐dimensional (2‐D) refraction tomographic method inverted these arrivals to reconstruct the subsurface velocity distribution [ Nemeth et al , 1997; Morey and Schuster , 1999].…”

Section: Seismic Tomographymentioning

confidence: 99%

“…A small perturbation to the velocity field is usually the basis for tomographic methods due to the linearization of the problem. This study uses a nonlinear tomographic method with a multigrid smoothing filter that has been successfully tested on synthetic models of colluvial wedges with velocity contrasts of up to 100% [ Nemeth et al , 1997; Morey and Schuster , 1999; Buddensiek , 2004; Sheng , 2004]. The inversion steps include: (1) the ray tracing integral is linearized, (2) the travel time for each ray path is computed by a finite difference solution to the eikonal equation [ Qin et al , 1992], (3) the velocity model is solved for, and (4) a new ray tracing integral is determined based on the new velocity model by measuring the sum of the squared travel time differences between the observed and computed times.…”

Section: Seismic Tomographymentioning

confidence: 99%

See 1 more Smart Citation

Tomographic imaging of late Quaternary faulting, Oquirrh Mountains, Utah

Mattson

2004

J. Geophys. Res.

View full text Add to dashboard Cite

[1] Seismic tomography can be used to image colluvial material in the subsurface by inverting first arrival travel times for velocity. Colluvial material deposited at the base of a fault-scarp free face often appears as a low-velocity zone (LVZ) on a tomogram because it is generally less compacted and cemented than the surrounding alluvium. A tomogram generated from a forward model of a synthetic velocity structure successfully images two LVZs stacked in the hanging wall of a normal fault. The Mercur fan, Oquirrh Mountains, Utah, provides an opportunity to look for stacked LVZs in a distributed fault zone. Three tomographic images across fault scarps on an intermediate age alluvial fan can be used to identify two stacked low-velocity zones. Interpretation of a fourth tomogram is less conclusive. These two low-velocity zones are interpreted as colluvial packages separated by higher-velocity alluvial material and suggest that tectonic activity is interspersed with pulses of fan building.

show abstract

Section: Seismic Tomographymentioning

confidence: 99%

Section: Seismic Tomographymentioning

confidence: 99%

Tomographic imaging of late Quaternary faulting, Oquirrh Mountains, Utah

Mattson

2004

J. Geophys. Res.

View full text Add to dashboard Cite

show abstract

“…Additional forward modellings are required for the line search. The initial velocity model c 0 ( x ) is the traveltime tomogram inverted by picked first arrivals (Nemeth, Normark and Qin ), and equation () is iteratively applied until the misfit functional E satisfies a stopping criterion…”

Section: Theorymentioning

confidence: 99%

An application of multiscale early arrival waveform inversion to shallow seismic data

Han

Hanafy

2013

Near Surface Geophysics

View full text Add to dashboard Cite

We estimate the near surface velocity distribution by applying multiscale early arrival waveform inversion (MEWI) to shallow seismic land data. This data set is collected at Wadi Qudaid in western Saudi Arabia with the purpose of characterizing the shallow subsurface for its water storage and reuse potential. To enhance the accuracy of MEWI, we correct for the attenuation effects with an estimated factor Q, and also extract a natural source wavelet from the data. We then applied MEWI to invert the processed data for tomograms on different scales starting from a traveltime tomogram as our initial velocity model. Results suggest that, compared to traveltime tomography, MEWI can generate a more highly resolved velocity tomogram from shallow seismic data by inverting its low‐frequency components on coarse grids and its high‐frequency components on fine grids. The estimated water table in the MEWI tomogram is generally consistent with, but 9% deeper than, the traveltime tomo gram, showing that the water storage in this wadi might be less than expected from the traveltime tomogram. We believe that the more accurate MEWI tomogram will make an economically important difference in assessing the storage potential of this wadi and wadis throughout the world.

show abstract

“…By defined the ray as a line connecting the nodes arranged on the edges of the cell the first-arrival travel times (defined as the fastest travel time of all ray paths) and ray paths are calculated by the ray tracing method based on Huygen's principle [26]. Also in this case the starting model is updated by the SIRT (for more information see [27][28][29]). For seismic refraction tomography data processing and interpretation the software Reflexw 6.0, developed by Sandmeier [22] was used.…”

Section: D Seismic Tomography Surveymentioning

confidence: 99%

2D and 3D seismic measurements to evaluate thecollapse risk of an important prehistoric cave insoft carbonate rock

Leucci

Giorgi

2015

Open Geosciences

View full text Add to dashboard Cite

Abstract:The southern part of the Apulia region (the Salento peninsula) has been the site of at least fifteen collapse events due to sinkholes in the last twenty years. The majority of these occurred in "soft" carbonate rocks (calcarenites). Man-made and/or natural cavities are sometimes assets of historical and archaeological significance. This paper provides a methodology for the evaluation of sinkhole hazard in "soft" carbonate rocks, combining seismic and mine engineering methods. A case study of a natural cavity which is called Grotta delle Veneri is illustrated. For this example the approach was: i) 2D and 3D seismic methods to study the physical-mechanical characteristics of the rock mass that constitutes the roof of the cave; and ii) scaled span empirical analysis in order to evaluate the instability of the crown pillar's caves.

show abstract

Dynamic smoothing in cross‐well tomography

Cited by 8 publications

References 0 publications

Tomographic imaging of late Quaternary faulting, Oquirrh Mountains, Utah

Tomographic imaging of late Quaternary faulting, Oquirrh Mountains, Utah

An application of multiscale early arrival waveform inversion to shallow seismic data

2D and 3D seismic measurements to evaluate thecollapse risk of an important prehistoric cave insoft carbonate rock

Contact Info

Product

Resources

About