Application Of Seismic Tomography Research Articles

Stability Assessment of a Bedding Rock Slope Using Q-slope and Seismic Tomography: A Case Study in the Ecuadorian Amazon

Roads are generally affected by slope failures, and these failures can increase when there are weathered materials and high rainfall. These circumstances occur in the sub-Andean zone of Ecuador. This is the region where the study area is located. The stability of a stratified rock slope, which is affecting a section of highway E45, was evaluated. The study slope is exposed to the road, but the upper part is covered by a soil-type material and dense vegetation that makes it challenging to study. We applied the Q-slope method and seismic tomography; these methods used together worked well, because they allowed to correlate and infer information about the quality of the rock mass, even in a fast and economical way. We also performed core drilling with core recovery in the crown of the slope and SPT test. The slope presented two well-differentiated zones; therefore, Q-slope values were calculated for each of these zones. The results show that the slope is unstable. The application of seismic tomography as an input parameter for calculating Q-slope was important because it allowed evaluating the stability where it is impossible to collect geomechanical information, correlate information taken at the foot of the slope, and define the depth of the bedrock.

Application of Cross-Hole Tomography for Assessment of Soil Stabilization by Grout Injection

Currently, the spread of megalopolises poses an ever-increasing necessity for underground space development for the purpose of the arrangement of transport communications, underground parking areas, trade areas, etc. The implementation of such projects entails a significant increase in the risk of accidents and damage to existing buildings within construction activity influence areas. The reduction of the risk of accidents during the construction of underground facilities within urban areas may only become possible with the identification of adverse factors negatively influencing existing buildings or a facility under erection and elaboration (to reduce such negative influence). The application of geophysical methods in complex assessments of the actual state of an encompassing mass significantly increases efficiency and the credibility of geotechnical monitoring. The application of seismic tomography significantly increases the resolution capability of surveys. Existing techniques, e.g., seismic tomography, allow for any depths to be investigated at a high resolution, even given constricted urban conditions. This article covers the practical applications of seismic tomography in qualitative assessments of actions and an efficiency evaluation of the injective stabilization of soil.

Application of seismic tomography for detecting structural faults in a Tertiary Formation

Seismic refraction technique is an increasingly useful geophysical tool for geotechnical studies in civil engineering work including the mapping of different soil formation of subsoil and detection of the bed rock. Additionally, wave velocity is a key parameter which correlates directly with significant geotechnical parameters of soils and rocks. Today, the evolution of the measurement technique in the field and the data processing allows to obtain tomographic images which increases its potential for applications to evaluate structuration of rock mass. This work describes the basic principles of seismic tomography and a case history of an application in civil works used to detect hidden faults in the sedimentary Gatun formation at the north of Panama. The correlation between the seismic profile and geologic profile obtained from boreholes showed very good agreement. Subsequent directed boreholes performed at the site confirmed the position and nature of the faults detected.

Application of seismic tomography for assessment of the railway substructure condition

This article presents results obtained in the research conducted on railway infrastructure in Serbia, which aimed at prediction of substructure condition based on the analysis of track quality. It presents the results of seismic tomography application as non-destructive procedure for assessment of railway substructure condition. Track geometry quality was assessed according to analysis of longitudinal level data, which was recorded during regular track geometry inspections. Track section for application of seismic tomography was chosen on the basis of analysed track geometry data recorded during the regular track geometry inspections in 2006, 2008, 2009, 2012, 2013 and 2014. Tomographic imaging of railway platform on Test Section enabled the creation of two-dimensional finite element model, which was used for determination of propagation speed of seismic P-waves. Seismic tomography on Test Section, which is the part of the international railway line Belgrade–Vrbnica, was performed in 2014. Obtained tomographic image was discussed and compared to track geometry data recorded during the regular track geometry inspections.

Seismic tomography: A window into deep Earth

The goal of this paper is to provide an overview of the current state of the art in seismic tomography, and trace its origins from pioneering work in the early 1970s to its present status as the pre-eminent tool for imaging the Earth's interior at a variety of scales. Due to length limitations, we cannot hope to cover every aspect of this diverse topic or include mathematical derivations of the underlying principles; rather, we will provide a largely descriptive coverage of the methodology that is targeted at readers not intimately familiar with the topic. The relative merits of local versus global parameterization, ray tracing versus wavefront tracking, backprojection versus gradient based inversion and synthetic testing versus model covariance are explored. A variety of key application areas are also discussed, including body wave traveltime tomography, surface wave tomography, attenuation tomography and ambient noise tomography. Established and emerging trends, many of which are driven by the ongoing rapid increases in available computing power, will also be examined, including finite frequency tomography, full waveform tomography and joint tomography using multiple datasets. Several practical applications of seismic tomography, including body wave traveltime, attenuation and surface waveform, are presented in order to reinforce prior discussion of theory.

Application of seismic tomography for detecting potential seepage paths in Bakhtyari Dam, Iran

Bakhtyari Dam and Hydropower Plant Project is one of the largest hydroelectric projects in Iran. This dam is located in Lorestan, in southern Iran, on the Bakhtyari river, which is a headstream of the Dez River. Previous gallery surveying showed that some open joints were present in the abutments. These joints may act as a good conduit for seepage. Five galleries were used to carry out seismic tomography in the right and left abutments (GR1, GR2 and GR3, GL2–GL3, totally 765 m). The objective of the tomography was to detect these weak zones susceptible for seepage. Velocity images obtained by P-wave travel time tomography indicated that in the level of GR2 gallery upward there is a large zone of low velocity. But the rock mass quality seems better in the left abutment. In spite of unfavorable condition in R 23 block (GR2–GR3), the P-wave velocity between GR2 and GR1 galleries is in the range of undisturbed limestone. Despite the presence of these weak zones, the placement of the dam is where the rock mass quality is good, and the design of the grout curtain could help to bypass the reservoir water away from these seepage paths.

Exploring a prehistoric site for remains of human structures by three‐dimensional seismic tomography

AbstractSeismic tomography is applied in the exploration of the subsurface of a prehistoric site for remains of human structures. Prehistoric sites are important for accessing information on human history in times of limited written evidence. Knowledge of the subsurface character and pattern of possible structural remains can be of great help in excavation design and assessment. A case history of the application of seismic tomography at Palamari prehistoric site, Skyros Island, Aegean Sea, Greece, is presented. Energy sources and recorders are placed on the ground surface. Travel time data are analysed and processed with three‐dimensional tomographic inversion software. Seismic velocity images of the subsurface are constructed. Modelling of the subsurface is used to improve the interpretation and assist in the evaluation of the significance and reliability of the results. Velocity variations are known to correlate well with the lithological character of the earth materials, thus providing important structural and lithological information of the subsurface. The results show a good correlation, in terms of location, geometry and dimensions, with expected and excavated real dimensions and pattern of the foundation and near‐surface structure. Copyright © 2005 John Wiley & Sons, Ltd.

An application of seismic tomography to basin focusing of seismic waves and Northridge earthquake damage

Damage during the 1994 Northridge earthquake was anomalously concentrated in Santa Monica, California. Aftershock studies suggest that the basin substructure caused localized amplification of seismic waves by focusing the energy. However, the geometry and velocities of the geological structure are uncertain, relying on extrapolation from widely separated boreholes. We present results of a tomographic study which includes inverting over 30,000 travel times from a seismic array experiment on a 194 station array and a 10‐km‐long Vibroseis survey. We find that the damage zone is located above a subbasin several kilometers deep where low‐velocity sediments of the northeastern Los Angeles basin are separated from higher‐velocity rocks of the Santa Monica Mountains by the steeply dipping Santa Monica‐Potrero Canyon fault zone. Three‐dimensional ray tracing through this structure shows that focusing of rays from the Northridge earthquake epicenter occurs in the region where damage was greatest and where aftershock amplitudes are magnified. We also find that near‐surface P velocities, while low in the Santa Monica basin, do not correlate with the zone of damage. In a related study [Baher et al., 2002], site effects determined from coda waves are better correlated with damage, suggesting that compliant site effects were also important in localizing the damage distribution. We conclude that the anomalous damage was caused by a combination of site and basin focusing effects. Such geometries may be quite common in earthquake zones worldwide where similar results have been observed.

New advances of seismic tomography and its applications to subduction zones and earthquake fault zones: A review

Abstract There have been significant advances in the theory and applications of seismic tomography in the last decade. These include the refinements in the model parameterization, 3‐D ray tracing, inversion algorithm, resolution and error analyses, joint use of local, regional and teleseismic data, and the addition of converted and reflected waves in the tomographic inversion. Applications of the new generation tomographic methods to subduction zones have resulted in unprecedentedly clear images of the subducting oceanic lithosphere and magma chambers in the mantle wedge beneath active arc volcanoes, indicating that geodynamic systems associated with the arc magmatism and back‐arc spreading are related to deep processes, such as the convective circulation in the mantle wedge and deep dehydration reactions in the subducting slab. High‐resolution tomographic imagings of earthquake fault zones in Japan and California show that rupture nucleation and earthquake generating processes are closely related to the heterogeneities of crustal materials and inelastic processes in the fault zones, such as the migration of fluids. Evidence also shows that arc magmatism and slab dehydration may also contribute to the generation of large crustal earthquakes in subduction regions.

Large-Scale Sparse Singular Value Computations

We present four numerical methods for computing the singular value decomposition (SVD) of large sparse matrices on a multiprocessor architecture. We emphasize Lanczos and subspace iteration-based methods for determining several of the largest singular triplets (singular values and corresponding left- and right-singular vectors) for sparse matrices arising from two practical applications: information retrieval and seismic reflection tomography. The target architectures for our implementations are the CRAY-2S/4–128 and Alliant FX/80. The sparse SVD problem is well motivated by recent information-retrieval techniques in which dominant singular values and their corresponding singular vectors of large sparse term-document matrices are desired, and by nonlinear inverse problems from seismic tomography applications which require approximate pseudo-inverses of large sparse Jacobian matrices. This research may help advance the development of future out-of-core sparse SVD methods, which can be used, for example, to handle extremely large sparse matrices 0 × (106) rows or columns associated with extremely large databases in query-based information-retrieval applications.

Cross borehole seismic tomography applications to mineral development : Davis, R W; Heinrichs, W E Min EngngV43, N8, Aug 1991. P1051–1056

Cross borehole seismic tomography (CBST) is a geophysical technique that allows definition of the distribution of some physical rock property between two boreholes. The method is similar to the computer-assisted tomography (CAT) scans used by the medical industry. This paper describes the method, its applications and the developing trends in its use that interest the mining industry. The idea of using tomography in connection with geophysical methods for measuring rock properties between boreholes has been around for three or four decades. Until the advent of high-speed, large-capacity computers, the necessary calculations were too formidable for production use. Another factor in the development of the technique has been the refinement of a mathematical base to meet the needs of the medical industry. The geophysical applications have benefited from this refinement.

Application of seismic tomography to the rock mass modelling : Ferrero, A M; Del Greco, O; Giani,G P; Ranieri, G; Stragiotti, L Proc International Conference on Mechanics of Jointed and Faulted Rock, Vienna, 18–20 April 1990P129–136. Publ Rotterdam: A A Balkema, 1990

Application of seismic tomography to the rock mass modelling : Ferrero, A M; Del Greco, O; Giani,G P; Ranieri, G; Stragiotti, L Proc International Conference on Mechanics of Jointed and Faulted Rock, Vienna, 18–20 April 1990P129–136. Publ Rotterdam: A A Balkema, 1990

Application of seismic tomography to the evaluation of rock mass properties : Inazaki, T; Jinbo, S; Takahashi, Y; Watanabe, F Proc 2nd International Symposium on Field Measurements in Geomechanics, Kobe, 6–9 April 1987V1, P347–356. Publ Rotterdam: A A Balkema, 1988

Application of seismic tomography to the evaluation of rock mass properties : Inazaki, T; Jinbo, S; Takahashi, Y; Watanabe, F Proc 2nd International Symposium on Field Measurements in Geomechanics, Kobe, 6–9 April 1987V1, P347–356. Publ Rotterdam: A A Balkema, 1988