Small‐Scale Array Experiments in Seismic‐Wave Gradiometry

2016 ◽  
Vol 87 (5) ◽  
pp. 1091-1103 ◽  
Author(s):  
Lauren M. Barker ◽  
Charles A. Langston
Keyword(s):  
Seismic Wave ◽  
Small Scale ◽  
Wave Gradiometry

The Effects of Measurement Uncertainties in Seismic-Wave Gradiometry

2015 ◽  
Vol 105 (6) ◽  
pp. 3143-3155 ◽  
Author(s):  
Christian Poppeliers ◽  
Elizabeth V. Evans
Keyword(s):  
Seismic Wave ◽  
Measurement Uncertainties ◽  
Wave Gradiometry

Numerical Simulation of Seismic Wave Propagation in Different Media

2014 ◽  
Vol 596 ◽  
pp. 616-619
Author(s):  
Zhi Ren Feng
Keyword(s):  
Numerical Simulation ◽  
Wave Propagation ◽  
Seismic Wave ◽  
Model Simulation ◽  
Homogeneous Medium ◽  
Seismic Wave Propagation ◽  
Seismic Exploration ◽  
Scale Model ◽  
Small Scale ◽  
Simulation Accuracy

Theory of elastic waves layered homogeneous medium or even medium for the study can not meet the actual demand for seismic exploration, especially for fine rock to construct reservoirs for the study, had to consider small-scale heterogeneity of seismic wave propagation effects. In this thesis, multi-scale model of a complex medium, in ensuring the premise to further improve simulation accuracy simulation efficiency issue, the introduction of a variable grid numerical simulation techniques, and were analyzed for different types of grid difference, establish a different media model simulation results verify the validity of simulation and analyzes its efficiency and accuracy problems.

Small-scale physical modeling of seismic-wave propagation using unconsolidated granular media

Geophysics ◽  
2014 ◽  
Vol 79 (6) ◽  
pp. T323-T339 ◽  
Author(s):  
Ludovic Bodet ◽  
Amine Dhemaied ◽  
Roland Martin ◽  
Régis Mourgues ◽  
Fayçal Rejiba ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Seismic Wave ◽  
Physical Modeling ◽  
Granular Media ◽  
Laser Doppler Vibrometer ◽  
Seismic Wave Propagation ◽  
Acoustic Mode ◽  
Physical Models ◽  
Small Scale ◽  
Near Surface

Laboratory physical modeling and laser-based experiments are frequently proposed to tackle theoretical and methodological issues related to seismic prospecting, e.g., when experimental validations of processing or inversion techniques are required. Lasers are mainly used to simulate typical field acquisition setups on homogeneous and consolidated materials assembled into laboratory-scale physical models (PMs) of various earth structures. We suggested the use of granular materials to study seismic-wave propagation in unconsolidated and porous media and target near-surface exploration and hydrogeologic applications. We designed and tested the reproducibility of an experimental procedure to build and probe PMs consisting of micrometric glass beads (GBs). A mechanical source and a laser-Doppler vibrometer were used to record small-scale seismic lines at the surface of three GBs models. When guided surface acoustic mode theory should prevail in such unconsolidated granular packed structure under gravity, we only considered elastic-wave propagation in stratified media to interpret recorded data. Thanks to basic seismic processing and inversion methods (first arrivals and dispersion analyses), we were able to correctly retrieve the gradients of pressure- and shear-wave velocities in our models. A 3D elastic finite difference simulation of the experiment offered, despite significant differences in terms of amplitudes, a supplementary validation of our approximation, as far as elastic properties of the medium were concerned.

scholarly journals Multiscale Method for Seismic Response of Near-Source Sites

2020 ◽  
Vol 2020 ◽  
pp. 1-19
Author(s):  
Shutao Li ◽  
Jingbo Liu ◽  
Zhou Yang ◽  
Xin Bao ◽  
Fei Wang ◽  
...  
Keyword(s):  
Seismic Response ◽  
Seismic Wave ◽  
Free Field ◽  
Multiscale Method ◽  
Small Scale ◽  
Structure Model ◽  
Underground Structures ◽  
Artificial Boundary ◽  
Site Structure ◽  
Source Site

The traditional source-site-structure model for the calculation of seismic response of underground structures at near-source sites is restricted by the grid scale and the size of the structure. As a result, an excessive number of elements in the model make the numerical solving process difficult. To solve problems such as an inefficient computation and challenging nonlinear simulation, a multiscale analysis method for the calculation of the seismic response of underground structures at near-source sites is developed. The generalized free-field seismic response of the near-source region is obtained by establishing a large-scale calculation model of the source site and is used to simulate the fracture mechanism of faults and the process of seismic wave propagation. Then, using the method of seismic wave input based on artificial boundary substructures, the free-field motion of the wave is transformed into the equivalent seismic load, which is the seismic wave input data for the small-scale region of interest. Finally, with the help of local elements with special shapes to realize the grid transition of different scales, a small-scale model with reasonable soil-underground structure interaction is established, and the seismic response of the overall model can be effectively solved. The calculation and analysis of the seismic response of underground structures in irregular terrain are carried out. Compared with the results obtained directly from the source-site-structure model, the multiscale method has satisfactory accuracy and meets the needs of engineering design. Since the number of elements is fewer and the calculation time is much shorter than those required by the traditional model, the advantages in computational efficiency of the new method are highlighted. In addition, the reflected waves are too weak to have a considerable impact on structures because of the great energy loss at the reflection interface, which further proves the feasibility of the closed artificial boundary substructure method.

Multiwavelet Seismic-Wave Gradiometry

2011 ◽  
Vol 101 (5) ◽  
pp. 2108-2121 ◽  
Author(s):  
C. Poppeliers
Keyword(s):  
Seismic Wave ◽  
Wave Gradiometry

Three-Dimensional Seismic-Wave Gradiometry for Scalar Waves

2013 ◽  
Vol 103 (4) ◽  
pp. 2151-2160 ◽  
Author(s):  
C. Poppeliers ◽  
P. Punosevac ◽  
T. Bell
Keyword(s):  
Seismic Wave ◽  
Three Dimensional ◽  
Scalar Waves ◽  
Wave Gradiometry

Vertical seismic wave gradiometry: Application at the San Andreas Fault Observatory at Depth

Geophysics ◽  
2016 ◽  
Vol 81 (3) ◽  
pp. D233-D243 ◽  
Author(s):  
Charles A. Langston ◽  
Mehari Melak Ayele
Keyword(s):  
Seismic Wave ◽  
San Andreas Fault ◽  
Seismic Profile ◽  
Spatial Gradient ◽  
Velocity Models ◽  
Anelastic Attenuation ◽  
Wave Inversion ◽  
Full Wave ◽  
San Andreas ◽  
Wave Gradiometry

We have developed vertical seismic wave gradiometry (VSWG) to estimate velocity, impedance, and attenuation structure in the vicinity of boreholes using borehole array waveforms of check-shot explosions near the borehole head. We have extended wave gradiometry (WG) theory from a purely local relation of the wavefield and wavefield spatial gradient to one that incorporated the ray ansatz over the length of the borehole for a traveling wave in a vertically inhomogeneous medium. We checked the ray assumption against acoustic full-wave synthetic seismograms, and it was found to yield robust measures of the medium velocity. Anelastic attenuation and impedance structure trade off, but in cases of high anelastic attenuation, realistic bounds can be placed on the seismic impedance that effectively constrains the average attenuation. We have applied these methods to data collected at the San Andreas Fault Observatory at Depth borehole in central California in 2005, and we found that the WG velocity estimate agreed well with the borehole acoustic log and previously determined vertical seismic profile results based on traveltime analysis except at the bottom of the hole, where refraction on a near-vertical fault affected the data. The average [Formula: see text] is approximately 20 in the frequency band of 10–30 Hz, and it is required to yield realistic values of impedance in the local medium. Application of VSWG yields appropriate, smoothed velocity models that can be used as an end product or as a starting model for full-wave inversion.

The Study of the Difference Methods with Variable Grids Seismic Wave Numerical Simulation in Multi-Scale Complex Media

2014 ◽  
Vol 1055 ◽  
pp. 254-258
Author(s):  
Jie Zhang ◽  
Fan Shun Meng ◽  
Yang Sen Li
Keyword(s):  
Numerical Simulation ◽  
Finite Difference ◽  
Finite Difference Method ◽  
Wave Field ◽  
Seismic Wave ◽  
Computational Efficiency ◽  
Difference Method ◽  
Staggered Grid ◽  
Small Scale ◽  
Simulation Accuracy

In the process of seismic wave field numerical simulation using finite difference method, the simulation accuracy and computational efficiency is one of the keys to the problem which is especially important to the numerical simulation of small scale geological body which velocity changes violently. In order to describe the local structure of medium subtly and guarantee the efficiency of the simulation, this article introduces the variable grid finite difference method to the staggered grid high-order finite difference numerical simulation on the basic of the traditional staggered grid finite difference algorithm to improve the staggered grid spatial algorithm and avoid the reduction of the simulation accuracy and computational efficiency caused by the interpolation factor. The results show that the variable staggered grid numerical simulation of finite difference algorithm can accurately depict the space variation of underground medium physical properties to further enhance the adaptability of numerical simulation of complex medium, it also can provide reliable basis for wave field imaging and the combined interpretation of p-wave and s-wave.

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