Detection of tunnels and boulders using shallow SH-SH reflected seismic waves

2019 ◽  
Vol 38 (6) ◽  
pp. 436-441 ◽  
Author(s):  
André J.-M. Pugin ◽  
Kevin Brewer ◽  
Timothy Cartwright ◽  
Steven L. Sargent
Keyword(s):  
Seismic Waves ◽  
Field Experiments ◽  
Sh Waves ◽  
Additional Advantage ◽  
Seismic Surveys ◽  
Shallow Seismic ◽  
Diffracted Waves ◽  
Seismic Sections ◽  
Ground Penetrating ◽  
Abandoned Coal Mine

We present three case studies on detecting buried glacial boulders, a sewage tunnel, and abandoned coal mine tunnels using shear-wave reflection methods. The seismic signature of such subsurface features is in the form of an isolated diffraction, distinctly recognized on seismic sections obtained from shallow seismic surveys using a transverse horizontal (H2) source and a multichannel landstreamer that consists of H2 geophones. We used H2 impulsive and vibrator sources with varying bandwidth. Based on field experiments with multicomponent recordings, we determined that the H2-H2 source-receiver configuration is the most optimal to generate downgoing horizontally polarized shear (SH) waves and upcoming SH reflected and diffracted waves. A shallow SH-SH image using a microvibe high-frequency sweep exhibits a wavelength between 1 and 2 m, which is comparable to that of a ground-penetrating radar image with the additional advantage of deeper penetration.

scholarly journals Modeling and Imaging of Multiscale Geological Media: Exploding Reflection Revisited

Geosciences ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 476
Author(s):  
Evgeny Landa ◽  
Galina Reshetova ◽  
Vladimir Tcheverda
Keyword(s):  
Seismic Waves ◽  
Fractured Reservoirs ◽  
Single Shot ◽  
Middle Point ◽  
Seismic Surveys ◽  
Geological Interpretation ◽  
Time Migration ◽  
Diffraction Imaging ◽  
Heterogeneous Multiscale ◽  
Seismic Sections

Computation of Common Middle Point seismic sections and their subsequent time migration and diffraction imaging provides very important knowledge about the internal structure of 3D heterogeneous geological media and are key elements for successive geological interpretation. Full-scale numerical simulation, that computes all single shot seismograms, provides a full understanding of how the features of the image reflect the properties of the subsurface prototype. Unfortunately, this kind of simulations of 3D seismic surveys for realistic geological media needs huge computer resources, especially for simulation of seismic waves’ propagation through multiscale media like cavernous fractured reservoirs. Really, we need to combine smooth overburden with microstructure of reservoirs, which forces us to use locally refined grids. However, to resolve realistic statements with huge multi-shot/multi-offset acquisitions it is still not enough to provide reasonable needs of computing resources. Therefore, we propose to model 3D Common Middle Point seismic cubes directly, rather than shot-by-shot simulation with subsequent stacking. To do that we modify the well-known "exploding reflectors principle" for 3D heterogeneous multiscale media by use of the finite-difference technique on the base of grids locally refined in time and space. We develop scalable parallel software, which needs reasonable computational costs to simulate realistic models and acquisition. Numerical results for simulation of Common Middle Points sections and their time migration are presented and discussed.

scholarly journals Control of Volunteer Glyphosate-Resistant Canola in Glyphosate-Resistant Sugar Beet

2015 ◽  
Vol 29 (1) ◽  
pp. 93-100 ◽  
Author(s):  
Vipan Kumar ◽  
Prashant Jha
Keyword(s):  
Sugar Beet ◽  
Field Experiments ◽  
Agricultural Research ◽  
Effective Control ◽  
Additional Advantage ◽  
Leaf Stage ◽  
Beet Root ◽  
Control Volunteer ◽  
Sugar Beet Root ◽  
Herbicide Programs

Occurrence of glyphosate-resistant (GR) canola volunteers in GR sugar beet is a management concern for growers in the Northern Great Plains. Field experiments were conducted at the Southern Agricultural Research Center near Huntley, MT, in 2011 and 2012 to evaluate effective herbicide programs to control volunteer GR canola in GR sugar beet. Single POST application of triflusulfuron methyl alone at the two-leaf stage of sugar beet was more effective at 35 compared with 17.5 g ai ha−1. However, rate differences were not evident when triflusulfuron methyl was applied as a sequential POST (two-leaf followed by [fb] six-leaf stage of sugar beet) program (17.5 fb 17.5 or 35 fb 35 g ha−1). Volunteer GR canola plants in the sequential POST triflusulfuron methyl–containing treatments produced little biomass (11 to 15% of nontreated plots) but a significant amount of seeds (160 to 661 seeds m−2). Ethofumesate (4,200 g ai ha−1) PRE followed by sequential POST triflusulfuron methyl (17.5 or 35 g ha−1) provided effective control (94 to 98% at 30 d after treatment [DAT]), biomass reduction (97%), and seed prevention of volunteer GR canola. There was no additional advantage of adding either desmedipham + phenmedipham + ethofumesate premix (44.7 g ha−1) or ethofumesate (140 g ha−1) to the sequential POST triflusulfuron methyl–only treatments. The sequential POST ethofumesate-only (140 fb 140 g ha−1) treatment provided poor volunteer GR canola control at 30 DAT, and the noncontrolled plants produced 6,361 seeds m−2, which was comparable to the nontreated control (7,593 seeds m−2). Sequential POST triflusulfuron methyl–containing treatments reduced GR sugar beet root and sucrose yields to 18 and 20%, respectively. Consistent with GR canola control, sugar beet root and sucrose yields were highest (95 and 91% of hand-weeded plots, respectively) when the sequential POST triflusulfuron methyl–containing treatments were preceded by ethofumesate (4,200 g ha−1) PRE. Growers should utilize these effective herbicide programs to control volunteer GR canola in GR sugar beet. Because of high canola seed production potential, as evident from this research, control efforts should be aimed at preventing seed bank replenishment of the GR canola volunteers.

Use Of Shallow Seismic Surveys In The Exploration Of Nearshore Placers Off Maharashtra Coast, India

1988 ◽  
Author(s):  
V.G. Rajamanickam ◽  
V.M. Ramanna ◽  
A.R. Gujar
Keyword(s):  
Seismic Surveys ◽  
Shallow Seismic

Shallow seismic surveys across the Ulsan fault near a province boundary in Korea

2003 ◽  
Author(s):  
K. Y. Kim ◽  
S. Y. Lee ◽  
D. H. Kim ◽  
H. C. Shin ◽  
Y. J. Kim ◽  
...  
Keyword(s):  
Seismic Surveys ◽  
Shallow Seismic

scholarly journals Separation of diffracted waves via SVD filter

2020 ◽  
Vol 17 (5) ◽  
pp. 1259-1271
Author(s):  
Hong-Yan Shen ◽  
Qin Li ◽  
Yue-Ying Yan ◽  
Xin-Xin Li ◽  
Jing Zhao
Keyword(s):  
Seismic Waves ◽  
Original Data ◽  
Identification Accuracy ◽  
Reflected Waves ◽  
Wave Separation ◽  
Imaging Results ◽  
Diffracted Waves ◽  
Fast Processing ◽  
The Difference ◽  
Value Decomposition

Abstract Diffracted seismic waves may be used to help identify and track geologically heterogeneous bodies or zones. However, the energy of diffracted waves is weaker than that of reflections. Therefore, the extraction of diffracted waves is the basis for the effective utilization of diffracted waves. Based on the difference in travel times between diffracted and reflected waves, we developed a method for separating the diffracted waves via singular value decomposition filters and presented an effective processing flowchart for diffracted wave separation and imaging. The research results show that the horizontally coherent difference between the reflected and diffracted waves can be further improved using normal move-out (NMO) correction. Then, a band-rank or high-rank approximation is used to suppress the reflected waves with better transverse coherence. Following, separation of reflected and diffracted waves is achieved after the filtered data are transformed into the original data domain by inverse NMO. Synthetic and field examples show that our proposed method has the advantages of fewer constraints, fast processing speed and complete extraction of diffracted waves. And the diffracted wave imaging results can effectively improve the identification accuracy of geological heterogeneous bodies or zones.

Antiplane Scattering of SH Waves by a Trapezoidal Valley with a Circular-Arc Alluvium in an Elastic Half Space

2015 ◽  
Vol 09 (03) ◽  
pp. 1550008 ◽  
Author(s):  
Chao Zhang ◽  
Qijian Liu ◽  
Peng Deng
Keyword(s):  
Seismic Waves ◽  
Mixed Boundary ◽  
Mixed Boundary Conditions ◽  
Expansion Method ◽  
Physical Region ◽  
Addition Theorem ◽  
Elastic Half Space ◽  
Response Analysis ◽  
Sh Waves ◽  
Finite Set

Both lithologic and topographic irregularities may trigger significant scattering phenomenon of seismic waves. In this study, a series solution is presented for the analysis of scattering of SH waves induced by a trapezoidal valley during earthquakes. An appropriate region matching technique is utilized to divide the physical region into four computational subregions. The wave motions of each subregion are obtained as an infinite series of wave functions with unknown coefficients in the respective cylindrical coordinates through wave function expansion method. The Graf's addition theorem is applied to transform the wave potentials of each subregion into the global coordinate. The mixed boundary conditions are solved by truncating the obtained infinite equations into a finite set. The effects of geometrical topographies and sedimentary properties on the amplification are analyzed and discussed in terms of steady-state and transient response analysis.

Experimental studies of potential improvements in the forest regeneration capabilities of "seed-containing aerial darts"

2000 ◽  
Vol 76 (3) ◽  
pp. 406-418 ◽  
Author(s):  
A. D. Wood
Keyword(s):  
Forest Regeneration ◽  
Field Experiments ◽  
Experimental Studies ◽  
Burned Areas ◽  
Spaced Seeds ◽  
Potential Applicability ◽  
Simulated Field ◽  
Ground Penetrating ◽  
Configuration Changes ◽  
Aerial Seeding

An evolving forest regeneration technique, based on the use of a "seed-containing aerial dart" (SCAD), provides for the delivery of seeds by helicopter through the distribution of darts, which serve as ground-penetrating containers for individual seeds. While many biological and technological aspects of this aerial sowing technique have been previously documented, the hitherto unpublished results of some growth experiments, carried out over a five-year period, are believed to offer the key to any future development. These simulated field experiments, although small in scale, demonstrate means for greatly improving the prospects for regeneration using aerial darts. Such means include dart configuration changes to provide for axially spaced seeds and the addition of slow-release fertilizer, when not in direct contact with seeds within the growth medium. Darts sown in the fall on mechanically undisturbed ground are shown not to be subject to frost heaving and lead to much earlier germination and faster growth than occurs with spring sowing. The presence of a surface layer of organic material is shown to be extremely beneficial in promoting vigorous seedling growth. The results confirm the potential applicability of the technique to sites, such as recently burned areas, with these characteristics, where acceptable regeneration performance is not an unrealistic objective. Key words: reforestation, regeneration, aerial reforestation, aerial seeding, aerial sowing, aerial darts, seeded darts, seed-containing darts, seed-containing aerial darts, helicopter seeding, helicopter sowing

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