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Alsamarraie, Mundher. "SEISMIC REFRACTION METHOD IN THE DETERMINATION OF SITE CHARACTERISTICS." Iraqi Geological Journal 53, no. 2D (2020): 53–63. http://dx.doi.org/10.46717/igj.53.2d.4ms-2020-10-26.
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Preliminary site properties need geophysical methods to determine it, the same as the large use of the seismic refraction method to detect the layers of soil and the depth reaching the bedrock. This study was conducted to find out the subsurface profile characteristics of a backyard field in UTM, Skudai following the principles of this method. The analysis of seismic data processed using ZondST2D software by determining the first arrival time until we get a block model of 2D shape based on the primary propagation of seismic velocity wave’s in soil layers. It was found that the investigated subsurface profile consists of four layers showing the level of weathering grade ranges from 600–4000 m/s based on the classification of rock mass in Malaysia. It was found that weathering rates decreased at higher depth, with the increase of density for the material and dampness reduction of seismic velocity. It was concluded that the survey of seismic refraction in development can be used only for shallow subsurface profiles and far from noise and disturbance.
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Ghanem, Fatima. "Geotechnical Engineering Evaluation of Superficial Deposits Utilizing Seismic Methods at Al al-Bayt University, Jordan." Iraqi Geological Journal 54, no. 1D (2021): 11–28. http://dx.doi.org/10.46717/igj.54.1d.2ms-2021-04-22.
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Integration of seismic refraction tomography and multi-channel analyses shear wave methods were used at Al al-Bayt university campus in Mafraq, NE Jordan to delineate the shallow subsurface layering and determine their geotechnical properties, in addition, to estimate the geotechnical engineering parameters of the superficial deposits for detailed purposes. The P-wave refraction velocities were found to range from 180 to 2300 m/s for the three identified layers which indicating superficial soil deposits with an increasing degree of compaction with depth. The S-wave velocities were found to lie in a narrow velocity range (250 to 600 m/s), which badly resolved the subsurface layering. Moreover, four soil samples were taken from the sites of seismic survey points for density calculations. The average calculated density was found to be 1.85 g/cm3. Two soil samples from nearby seismic profile-1 and seismic profile-4 were tested for geotechnical properties. The results showed that the seismic method is an effective tool to estimate the different elastic moduli; Poisson's ratio, Young's modulus, Bulk modulus, Shear modulus, Lame's constants, and geotechnical engineering parameters; N-value, bearing capacity, material index, concentration index, and stress ratio of the superficial soil deposits. The study recommends conducting a detailed geophysical study before starting any type of geoengineering construction in the area.
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Umor, Mohd Rozi, Mohd Hariri Arifin, and Nora Muda. "The Seismic Refraction Survey to Determine the Depth of Bedrock at the Damansara Area for Horizontal Directional Drilling Method Application." Applied Science and Innovative Research 3, no. 3 (2019): p123. http://dx.doi.org/10.22158/asir.v3n3p123.
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The seismic reflection survey conducted along the road at Damansara to determine the depth of bedrock in order to justify whether HDD method can be utilize to store the fiber optic cable. 10 line seismic survey performed along 1.2 km roadside. The result show that the subsurface profile represent by two layer of earth materials that is topsoil and bedrock granite. Determination between topsoil and granite based on the values of seismic velocity. The boundary between granite and soil interpreted by a velocity value 1,200 m/s. If the velocity values is less than 1,200 m/s, it interpreted as soil or highly weathered rock. Meanwhile the velocity value more than 1,200 m/s is refer as rock and hard to excavate especially using HDD method. The study shows that the general thickness of topsoil along the road in Damansara is around 2.0 to 4.0 m. The minimum thickness of topsoil is 1.0 m and maximum found around 6.0 m. The bedrock observed very shallow and not suitable for HDD method to implement.
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Kurtuluş, Cengiz, Ibrahim Sertcelik, Fadime Sertçelik, Hamdullah Livaoğlu, and Cüneyt Şaş. "Investigation of Soil Characterization in Hatay Province in Turkey by Using Seismic Refraction, Multichannel Analysis of Surface Waves and Microtremor." Earth Sciences Research Journal 24, no. 4 (2021): 473–84. http://dx.doi.org/10.15446/esrj.v24n4.79123.
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In this study, shallow seismic surveys, including seismic refraction, Multichannel Analysis of Surface Waves (MASW), Refraction Microtremor (ReMi), and Microtremor measurements were conducted to estimate site characterization at 26 strong-motion stations of AFAD (Disaster and Emergency Management Presidency) in the province of Hatay, situated in one of the most seismically active regions in southern Turkey. The Horizontal to vertical spectral ratio (HVSR) technique was applied, using smoothed Fourier spectra derived from a long duration series to determine dominant frequency values at different amplification levels. Shear wave velocity up to 30 m of the ground was detected with MASW analysis. In the ReMi analysis, up to 80 m was reached with a corresponding average of 650 m/s shear wave velocity. The shear wave velocities estimated by the MASW method up to 30 m were compared with those found by the ReMi method, and they were observed to be very compatible. The province of Hatay was classified according to Vs30 based NEHRP Provisions, Eurocode-8, the Turkish Building Earthquake Regulation (TBDY-2018), and Rodriguez-Marek et al. (2001). The shear-wave velocity (Vs30), Horizontal to Vertical ratio’s (H/V) peak amplitude, dominant period, and site class of each site were determined. The H/V peak amplitudes range between 1.9 and 7.6, while the predominant periods vary from 0.23 sec to 2.94sec in the study area. These results are investigated to explain the consistency of site classification schemes.
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Mohamad, Habib M., B. Kasbi, M. Baba, Z. Adnan, S. Hardianshah, and S. Ismail. "Investigating Peat Soil Stratigraphy and Marine Clay Formation Using the Geophysical Method in Padas Valley, Northern Borneo." Applied and Environmental Soil Science 2021 (May 18, 2021): 1–12. http://dx.doi.org/10.1155/2021/6681704.
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A geophysical survey including electrical resistivity tomography (ERT), induced polarization (IP), and seismic refraction (SR) was carried out to estimate peatland thickness in Beaufort District, Eastern Malaysia. Peatlands are important natural carbon storage and play a key role in the global carbon cycle. The ERT and IP studies were performed along three profiles over different peat thicknesses using Schlumberger configuration. The SR survey was carried out using vertical geophones along the same profiles. The peat soil material was characterized by low seismic velocity and high resistivity. Our results show that ERT and IP methods were able to clearly detect the interface between the peat soil and marine clay underneath. These layers differ greatly in geoelectrical characteristics showing clear contrast, thus enabling the delineation of peat soil stratigraphy, while the SR image obtained was not able to determine the base of the peat soil layer as the stiffness difference on the transition layer was very small. Overall, it was concluded that the ERT and IP method offer a useful alternative in delineating the peat soil stratigraphy. The combined application of ERT and IP method with the conventional boring method meets the demand for large volume peat stratigraphy mapping, which, moreover, has various ecological conditions and undulating strata.
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Demanet, Donat, François Renardy, Kris Vanneste, Denis Jongmans, Thierry Camelbeeck, and Mustapha Meghraoui. "The use of geophysical prospecting for imaging active faults in the Roer Graben, Belgium." GEOPHYSICS 66, no. 1 (2001): 78–89. http://dx.doi.org/10.1190/1.1444925.
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As part of a paleoseismological investigation along the Bree fault scarp (western border of the Roer Graben), various geophysical methods [electrical profiling, electromagnetic (EM) profiling, refraction seismic tests, electrical tomography, ground‐penetrating radar (GPR), and high‐resolution reflection seismic profiles] were used to locate and image an active fault zone in a depth range between a few decimeters to a few tens of meters. These geophysical investigations, in parallel with geomorphological and geological analyses, helped in the decision to locate trench excavations exposing the fault surfaces. The results could then be checked with the observations in four trenches excavated across the scarp. Geophysical methods pointed out anomalies at all sites of the fault position. The contrast of physical properties (electrical resistivity and permittivity, seismic velocity) observed between the two fault blocks is a result of a differences in the lithology of the juxtaposed soil layers and of a change in the water table depth across the fault. Extremely fast techniques like electrical and EM profiling or seismic refraction profiles localized the fault position within an accuracy of a few meters. In a second step, more detailed methods (electrical tomography and GPR) more precisely imaged the fault zone and revealed some structures that were observed in the trenches. Finally, one high‐resolution reflection seismic profile imaged the displacement of the fault at depths as large as 120 m and filled the gap between classical seismic reflection profiles and the shallow geophysical techniques. Like all geophysical surveys, the quality of the data is strongly dependent on the geologic environment and on the contrast of the physical properties between the juxtaposed formations. The combined use of various geophysical techniques is thus recommended for fault mapping, particularly for a preliminary investigation when the geological context is poorly defined.
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Moradi, Shirin, Thomas Heinze, Jasmin Budler, Thanushika Gunatilake, Andreas Kemna, and Johan Alexander Huisman. "Combining Site Characterization, Monitoring and Hydromechanical Modeling for Assessing Slope Stability." Land 10, no. 4 (2021): 423. http://dx.doi.org/10.3390/land10040423.
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Rainfall-induced landslides are a disastrous natural hazard causing loss of life and significant damage to infrastructure, farmland and housing. Hydromechanical models are one way to assess the slope stability and to predict critical combinations of groundwater levels, soil water content and precipitation. However, hydromechanical models for slope stability evaluation require knowledge about mechanical and hydraulic parameters of the soils, lithostratigraphy and morphology. In this work, we present a multi-method approach of site characterization and investigation in combination with a hydromechanical model for a landslide-prone hillslope near Bonn, Germany. The field investigation was used to construct a three-dimensional slope model with major geological units derived from drilling and refraction seismic surveys. Mechanical and hydraulic soil parameters were obtained from previously published values for the study site based on laboratory analysis. Water dynamics were monitored through geoelectrical monitoring, a soil water content sensor network and groundwater stations. Historical data were used for calibration and validation of the hydromechanical model. The well-constrained model was then used to calculate potentially hazardous precipitation events to derive critical thresholds for monitored variables, such as soil water content and precipitation. This work introduces a potential workflow to improve numerical slope stability analysis through multiple data sources from field investigations and outlines the usage of such a system with respect to a site-specific early-warning system.
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Mreyen, A.-S., L. Cauchie, M. Micu, A. Onaca, and H.-B. Havenith. "Multiple geophysical investigations to characterize massive slope failure deposits: application to the Balta rockslide, Carpathians." Geophysical Journal International 225, no. 2 (2021): 1032–47. http://dx.doi.org/10.1093/gji/ggab028.
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SUMMARYOrigins of ancient rockslides in seismic regions can be controversial and must not necessarily be seismic. Certain slope morphologies hint at a possible coseismic development, though further analyses are required to better comprehend their failure history, such as modelling the slope in its pre-failure state and failure development in static and dynamic conditions. To this effect, a geophysical characterization of the landslide body is crucial to estimate the possible failure history of the slope. The Balta rockslide analysed in this paper is located in the seismic region of Vrancea-Buzau, Romanian Carpathian Mountains and presents a deep detachment scarp as well as a massive body of landslide deposits. We applied several geophysical techniques on the landslide body, as well as on the mountain crest above the detachment scarp, in order to characterize the fractured rock material as well as the dimension of failure. Electrical resistivity measurements revealed a possible trend of increasing fragmentation of rockslide material towards the valley bottom, accompanied by increasing soil moisture. Several seismic refraction surveys were performed on the deposits and analysed in form of P-wave refraction tomographies as well as surface waves, allowing to quantify elastic parameters of rock. In addition, a seismic array was installed close to the detachment scarp to analyse the surface wave dispersion properties from seismic ambient noise; the latter was analysed together with a colocated active surface wave analysis survey. Single-station ambient noise measurements completed all over the slope and deposits were used to further reveal impedance contrasts of the fragmented material over in situ rock, representing an important parameter to estimate the depth of the shearing horizon at several locations of the study area. The combined methods allowed the detection of a profound contrast of 70–90 m, supposedly associated with the maximum landslide material thickness. The entirety of geophysical results was used as basis to build up a geomodel of the rockslide, allowing to estimate the geometry and volume of the failed mass, that is, approximately 28.5–33.5 million m3.
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Nogueira, Pedro Vencovsky, Marcelo Peres Rocha, Welitom Rodrigues Borges, Eduardo Xavier Seimetz, and Márcio Maciel Cavalcanti. "COMPARISON BETWEEN RESULTS OF SEISMIC REFRACTION AND STANDARD PENETRATION TEST (SPT) TO STUDY SHALLOW GEOLOGICAL SUBSURFACE IN AN URBAN AREA OF BRASÍLIA, BRAZIL." Revista Brasileira de Geofísica 32, no. 4 (2014): 673. http://dx.doi.org/10.22564/rbgf.v32i4.536.
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ABSTRACT. The most common procedure for an engineering project/construction is the use of direct survey, borehole and Standard Penetration Test (SPT). Thisprovides punctual information of the geology at the site, and many boreholes are necessary along the construction site, representing a significant amount of the budgetfor the construction and to help develop a better geological understand/map of the site. The use of geophysical methods allows to study the subsurface by indirectmeans, with low cost, and enable to cover large areas if compared to direct surveys. Geophysical methods are increasingly being used in engineering works, however, inBrazil the use in engineering projects is still scarce. In this work was used shallow seismic refraction method to study the shallow subsurface in an area along the futuretrack of the subway system of Bras´ılia, Brazil. The refraction results (P-wave) were compared with previous existing data from Standard Penetration Test (SPT), and soilprofile description. The seismic was used to study the subsurface geology, and SPT data were used to compare the seismic results. We observed a good correlationfor the depths obtained through each method, mostly in the north portion of the line, when the SPT was near the line, indicating that its results are influenced by thesame mechanical parameters, related to soil strength. Our results motivate the use of seismic refraction as a tool to optimize the direct investigation methods for bettergeotechnical characterization of the medium.Keywords: shallow seismic refraction, standard penetration test (SPT), geotechnical study. RESUMO. O procedimento inicial mais comum em um projeto de engenharia é o uso de pesquisa direta, por meio de sondagens e Índice de Resistência à Penetração (SPT, em inglês). Estas ferramentas fornecem informações pontuais acerca da geologia local, sendo necessárias diversas sondagens para desenvolver um bom entendimento geológico/geotécnico da região, fazendo com que as sondagens representem uma quantidade significativa do orçamento da obra de engenharia. O usode métodos geofísicos permite estudar a subsuperfície por meio indireto, com baixo custo, e possibilita cobrir grandes áreas, quando comparado ao uso exclusivo desondagens diretas. Métodos geofísicos estão sendo cada vez mais utilizados em obras de engenharia, no entanto, o seu uso em projetos de engenharia no Brasil aindaé escasso. Neste trabalho foi utilizado o método de sísmica de refração rasa para estudar a subsuperfície em uma área ao longo do futuro trecho do sistema de metrô de Brasília, Brasil. Os resultados de refração (onda P) foram comparados com os dados pré-existentes de SPT e descrição do solo. A sísmica foi empregada para estudara geologia da subsuperfície, os dados SPT foram utilizados para comparar com os resultados sísmicos. Observou-se uma boa correlação para as profundezas obtidas através de cada método, principalmente na porção norte da linha, região em que o SPT está mais próximo da linha, indicando que os seus resultados são influenciados pelos mesmos parâmetros mecânicos, relacionados com a resistência do solo. Nossos resultados motivam o uso de refração sísmica como uma ferramenta para aperfeiçoar os métodos de investigação direta, com objetivo de gerar uma melhor caracterização geotécnica do meio.Palavras-chave: sísmica de refração rasa, índice de resistência à penetração, estudo geotécnico.
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Groves, Paul, Giovanni Cascante, Dave Dundas, and P. K. Chatterji. "Use of geophysical methods for soil profile evaluation." Canadian Geotechnical Journal 48, no. 9 (2011): 1364–77. http://dx.doi.org/10.1139/t11-044.
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A geophysical investigation was performed to evaluate the effectiveness of three geophysical methods (electrical resistivity imaging (ERI), seismic refraction (SR), and multiple-channel analysis of surface waves (MASW)) for geotechnical site characterization in swamps and environmentally sensitive wetland areas. The geophysical test results were verified against the results from borehole and cone penetrometer test logs. The ERI results were best for determining the depth to the glacial till. However, the resolution of the ERI survey was not sufficient to accurately predict the upper lithologies. The electrode spacing (4 m) was instead selected to reliably predict the depth to the till, which in this case varied between 4.6 and 10.7 m. The SR results overestimated the depth to the till because of the presence of a stiffness reversal. The MASW results predicted the depth to the refusal till layer less accurately than the ERI method. However, this method was able to detect the three distinct layers above the till, even though the layer thicknesses were consistently underestimated. The complementary use of geophysical techniques was a successful approach in determining the main soil units and the depth to the competent layer (till) at the site. These methods can be used as a basis for further development to optimize a procedure to reduce the number of boreholes required for conventional site investigations in areas that are environmentally sensitive or where access is restricted.
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Behm, Michael, Feng Cheng, Anna Patterson, and Gerilyn S. Soreghan. "Passive processing of active nodal seismic data: estimation of <i>V</i><sub>P</sub>∕<i>V</i><sub>S</sub> ratios to characterize structure and hydrology of an alpine valley infill." Solid Earth 10, no. 4 (2019): 1337–54. http://dx.doi.org/10.5194/se-10-1337-2019.
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Abstract. The advent of cable-free nodal arrays for conventional seismic reflection and refraction experiments is changing the acquisition style for active-source surveys. Instead of triggering short recording windows for each shot, the nodes are continuously recording over the entire acquisition period from the first to the last shot. The main benefit is a significant increase in geometrical and logistical flexibility. As a by-product, a significant amount of continuous data might also be collected. These data can be analyzed with passive seismic methods and therefore offer the possibility to complement subsurface characterization at marginal additional cost. We present data and results from a 2.4 km long active-source profile, which have recently been acquired in western Colorado (US) to characterize the structure and sedimentary infill of an over-deepened alpine valley. We show how the “leftover” passive data from the active-source acquisition can be processed towards a shear wave velocity model with seismic interferometry. The shear wave velocity model supports the structural interpretation of the active P-wave data, and the P-to-S-wave velocity ratio provides new insights into the nature and hydrological properties of the sedimentary infill. We discuss the benefits and limitations of our workflow and conclude with recommendations for the acquisition and processing of similar datasets.
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Bücker, Matthias, Adrián Flores Orozco, Jakob Gallistl, et al. "Integrated land and water-borne geophysical surveys shed light on the sudden drying of large karst lakes in southern Mexico." Solid Earth 12, no. 2 (2021): 439–61. http://dx.doi.org/10.5194/se-12-439-2021.
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Abstract. Karst water resources play an important role in drinking water supply but are highly vulnerable to even slight changes in climate. Thus, solid and spatially dense geological information is needed to model the response of karst hydrological systems to such changes. Additionally, environmental information archived in lake sediments can be used to understand past climate effects on karst water systems. In the present study, we carry out a multi-methodological geophysical survey to investigate the geological situation and sedimentary infill of two karst lakes (Metzabok and Tzibaná) of the Lacandon Forest in Chiapas, southern Mexico. Both lakes present large seasonal lake-level fluctuations and experienced an unusually sudden and strong lake-level decline in the first half of 2019, leaving Lake Metzabok (maximum depth ∼25 m) completely dry and Lake Tzibaná (depth ∼70 m) with a water level decreased by approx. 15 m. Before this event, during a lake-level high stand in March 2018, we collected water-borne seismic data with a sub-bottom profiler (SBP) and transient electromagnetic (TEM) data with a newly developed floating single-loop configuration. In October 2019, after the sudden drainage event, we took advantage of this unique situation and carried out complementary measurements directly on the exposed lake floor of Lakes Metzabok and Tzibaná. During this second campaign, we collected time-domain induced polarization (TDIP) and seismic refraction tomography (SRT) data. By integrating the multi-methodological data set, we (1) identify 5–6 m thick, likely undisturbed sediment sequences on the bottom of both lakes, which are suitable for future paleoenvironmental drilling campaigns, (2) develop a comprehensive geological model implying a strong interconnectivity between surface water and karst aquifer, and (3) evaluate the potential of the applied geophysical approach for the reconnaissance of the geological situation of karst lakes. This methodological evaluation reveals that under the given circumstances, (i) SBP and TDIP phase images consistently resolve the thickness of the fine-grained lacustrine sediments covering the lake floor, (ii) TEM and TDIP resistivity images consistently detect the upper limit of the limestone bedrock and the geometry of fluvial deposits of a river delta, and (iii) TDIP and SRT images suggest the existence of a layer that separates the lacustrine sediments from the limestone bedrock and consists of collapse debris mixed with lacustrine sediments. Our results show that the combination of seismic methods, which are most widely used for lake-bottom reconnaissance, with resistivity-based methods such as TEM and TDIP can significantly improve the interpretation by resolving geological units or bedrock heterogeneities, which are not visible from seismic data. Only the use of complementary methods provides sufficient information to develop comprehensive geological models of such complex karst environments
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Shang, Yan-Jun, Chang-Gen Yang, Wei-Jun Jin, et al. "Application of Integrated Geophysical Methods for Site Suitability of Research Infrastructures (RIs) in China." Applied Sciences 11, no. 18 (2021): 8666. http://dx.doi.org/10.3390/app11188666.
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Research Infrastructures (RIs) are essential to achieve excellence in innovative scientific research. However, because of limited land availability and specific geological requirements, evaluating the viability of a site for a new RI can be a challenging task. Stringent safety construction requirements include developing site-specific architectural and geoengineering solutions, minimizing construction disturbances, and reinforcing rock and soil in a timely fashion. For successful development of the RIs in China, such as the Daya Bay Neutrino Laboratory (DBNL) and the China Spallation Neutron Source (CSNS), an integrated approach of joint geophysical methods including the electrical resistivity tomography (ERT), controlled-source audio-frequency magneto telluric (CSAMT)), gravity and seismic refraction methods, and geological mapping and surveys were carried out. Geophysical parameters, such as electrical resistivity, density, and seismic velocity, show inverse proportion to the degree of rock fracturing or weathering. The results show that the low values of geophysical parameters suggest the weathered/fractured rock, while high values reveal the fresh bedrock. The Engineering Geological Suitability Index (EGSI) value can represent the individual EGSI values at a constant and summed over varying depths. EGSI methodology is an improvement on the existing siting process and has been applied to CSNS. Our integrated approach provides clearer insight into the subsurface for site suitability of RIs in challenging geological engineering conditions and removes any ambiguity caused by a single geophysical parameter. The obtained geological knowledge of the area not only provides engineers with much-needed information about the construction conditions of a potential site but also gives scientists the opportunity to explore the local geology. In this study, we demonstrate our innovative approach for siting RIs, as demonstrated by the synthetic evaluation of the site location and utilization for two established RIs (DBNL and CSNS).
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Mitchell, James F., and Richard J. Bolander. "Structural interpretation using refraction velocities from marine seismic surveys." GEOPHYSICS 51, no. 1 (1986): 12–19. http://dx.doi.org/10.1190/1.1442026.
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Subsurface structure can be mapped using refraction information from marine multichannel seismic data. The method uses velocities and thicknesses of shallow sedimentary rock layers computed from refraction first arrivals recorded along the streamer. A two‐step exploration scheme is described which can be set up on a personal computer and used routinely in any office. It is straightforward and requires only a basic understanding of refraction principles. Two case histories from offshore Peru exploration demonstrate the scheme. The basic scheme is: step (1) shallow sedimentary rock velocities are computed and mapped over an area. Step (2) structure is interpreted from the contoured velocity patterns. Structural highs, for instance, exhibit relatively high velocities, “retained” by buried, compacted, sedimentary rocks that are uplifted to the near‐surface. This method requires that subsurface structure be relatively shallow because the refracted waves probe to depths of one hundred to over one thousand meters, depending upon the seismic energy source, streamer length, and the subsurface velocity distribution. With this one requirement met, we used the refraction method over a wide range of sedimentary rock velocities, water depths, and seismic survey types. The method is particularly valuable because it works well in areas with poor seismic reflection data.
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Rolph, Tim C., John Shaw, Edward Derbyshire, and An Zhisheng. "Determining Paleosol Topography Using Seismic Refraction." Quaternary Research 42, no. 3 (1994): 350–53. http://dx.doi.org/10.1006/qres.1994.1085.
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AbstractThe seismic refraction reversed profiling technique has been used to investigate the topography of the last interglacial soil (paleosol S1) within the central Chinese Loess Plateau near Xifeng. The results suggest an essentially flat-lying soil at a depth which varies by only a few meters over an area of more than 10 km2. In addition, the results indicate a high-velocity layer at 50-60 m depth which is thought to coincide with a layer of carbonate concretions at the base of paleosol S5. The results agree well with the local loess-paleosol stratigraphy for this area and indicate that the seismic refraction method is a rapid technique for investigating paleotopography.
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Nurcandra, Nakif, Darsono D, and Sorja Koesuma. "Penentuan Tingkat Kekerasan Batuan Menggunakan Metode Seismik Refraksi di Jatikuwung Karanganyar." INDONESIAN JOURNAL OF APPLIED PHYSICS 3, no. 01 (2016): 29. http://dx.doi.org/10.13057/ijap.v3i01.1212.
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<span>It has been done a research about the determination of rock hardness level by using refraction <span>seismic method in Jatikuwung Karanganyar. The research is done by using <span><em>Seismograph PASI </em><span><em>16S24-P </em><span>with the path length of 48 meters, distance between <span><em>geophone </em><span>2 meters, 5 <span><em>shots </em><span>in <span>each spread and there are four surveys part totally. The processing data is done by using <span>SeisImager software with <span><em>Plotrefa </em><span>and <span><em>Pickwin95 </em><span>program.We use <span><em>intercept time </em><span>method for <span>data processing. The determination of rock hardness use <span><em>Gardner’s relationship </em><span>formula. <span>Based on interpretation, there are three layers lithology structure with P wave propagation <span>velocity of 200-1800 m/s and its density of 1.17<span>–<span>1.93 gr/cc. Based on velocity analysis we <span>determine the velocity of first layer is 200-700 m/s, second layer 700-1500 m/s, and third <span>layer 1500-1800 m/s. The subsurface hardness lithology consists of <span><em>top soil</em><span>, sands and <span>unsaturated pebble (1.17<span>–<span>1.59 gr/cc) with the depth 2<span>–<span>4 meters in the first layer, saturated<br /><span>sands, saturated pebble, and alluvium (1.59<span>–<span>1.93 gr/cc) with the depth 9.5<span>–<span>11.5 meters in the <span>second layer, and clay and sands (1.93<span>–<span>2.02 gr/cc) with the depth of 5.5<span>–<span>6 meters in the third <span>layer. The rock hardness is located at the depth betwen 12 <span>– <span>20 meters.</span></span></span></span></span></span></span></span></span></span></span></span></span><br /></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span>
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Leung, Tak Ming. "Controls of traveltime data and problems of the generalized reciprocal method." GEOPHYSICS 68, no. 5 (2003): 1626–32. http://dx.doi.org/10.1190/1.1620636.
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Traveltime data required for 2D seismic refraction surveys are 2D first arrivals. To obtain a high degree of consistency between traveltime data and the seismic model, it is important to verify that traveltime data are appropriate for interpretation or an inversion process. Controls or checkpoints presented here inspect compatibility among traveltime data. Similar to the ray‐trace check on the consistency of interpretation, these controls provide an objective means of quality assessment of seismic refraction data. The theoretical aspects of the generalized reciprocal method (GRM) are studied because concerns have been raised regarding the accuracy of some interpretations using this method. The problem of the GRM is that the optimum XY value, which is the most important parameter in the method, is assumed to be twice the offset distance. Consequently, based on this unproven assumption, the efficacy of the optimum XY value is somewhat exaggerated.
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Syifa, Resi Wasilatus, Nur Ichsan Sumardani, Nur Amalia Dewi, Teti Febrianti, Jauhari Arifin, and Bebeh Wahid Nuryadin. "Identification of Landfill Using Refraction Seismic Method in LIPI Area - Bandung." Risenologi : Jurnal Sains, Teknologi, Sosial, Pendidikan, dan Bahasa 5, no. 1 (2020): 26–37. http://dx.doi.org/10.47028/j.risenologi.2020.51.76.
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Research has been carried out using seismic refraction in the LIPI area - Bandung, which aims to determine the land of embankment in the area. Retrieval of field data was carried out using geometric Es-3000 tool along 46 meters with a spacing of 2 meters and a 7 shoot punch consisting of 2 phantom shoots beginning and ending. Data processing is done by the first step, namely by geometric editing so that data can be read by the computer. The inversion process is done by seismimager software which consists of pickwin to extract data and plotera for modeling the subsurface layer. The results of the data interpretation show the P wave velocity from 315 - 435 m / s. layer grouping based on P wave velocity is at the first color layer having a wave velocity of about 315 - 342 m / s, the second color layer has a wave speed of 355-382 m / s, and the third color layer has a speed of 359 - 422 m / s and thick layer more than 435. Based on the lithological classification of subsurface rock layers, this study area tends to have a layer of soil type with a depth of 5 meters, and can be said to be a layer of soil deposits because of the formation of soil structures that tend to be new
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Bery, Andy A. "Merge-Optimization Method of Combined Tomography of Seismic Refraction and Resistivity Data." ISRN Geophysics 2012 (December 31, 2012): 1–6. http://dx.doi.org/10.5402/2012/293132.
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This paper discussed a novel application called merge-optimization method that combines resistivity and seismic refraction data to provide a detailed knowledge of the studied site. This method is interesting because it is able to show strong accuracy of two geophysical imaging methods based on many of data points collected from the conducted geophysical surveys of disparate data sets based strictly on geophysical models as an aid for model integration for two-dimensional environments. The geophysical methods used are high resolution methods. The resistivity imaging used in this survey is able to resolve the subsurface condition of the studied site with low RMS error (less than 2.0%) and 0.5 metre electrodes interval. For seismic refraction method, high resolution of seismic is used for correlation with resistivity results. Geophones spacing is 1.0 metre and the total number of shot-points is 15, which provides very dense data point. The algorithms of merge-optimization have been applied to two data sets collected at the studied site. The resulting images have been proven to be successful because they satisfy the data and are geometrically similar. The regression coefficient found for conductivity-resistivity correlation is 95.2%.
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Malehmir, Alireza, Magdalena Markovic, Paul Marsden, et al. "Sparse 3D reflection seismic survey for deep-targeting iron oxide deposits and their host rocks, Ludvika Mines, Sweden." Solid Earth 12, no. 2 (2021): 483–502. http://dx.doi.org/10.5194/se-12-483-2021.
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Abstract. Many metallic mineral deposits have sufficient physical property contrasts, particularly density, to be detectable using seismic methods. These deposits are sometimes significant for our society and economic growth and can help to accelerate the energy transition towards decarbonization. However, their exploration at depth requires high-resolution and sensitive methods. Following a series of 2D seismic trials, a sparse, narrow source–receiver azimuth, 3D seismic survey was conducted in the Blötberget mine, in central Sweden, covering an area of approximately 6 km2 for deep-targeting iron oxide deposits and their host rock structures. The survey benefited from a collaborative work by putting together 1266 seismic recorders and a 32 t vibrator, generating 1056 shot points in a fixed geometry setup. Shots were fired at every 10 m where possible, and receivers were placed at every 10–20 m. Notable quality data were acquired despite the area being dominated by swampy places as well as by built-up roads and historical tailings. The data processing had to overcome these challenges for the static corrections and strong surface waves in particular. A tailored for hardrock setting and processing workflow was developed for handling such a dataset, where the use of mixed 2D and 3D refraction static corrections was relevant. The resulting seismic volume is rich in terms of reflectivity, with clear southeast-dipping reflections originating from the iron oxide deposits extending vertically and laterally at least 300 m beyond what was known from available boreholes. As a result, we estimate potential additional resources from the 3D reflection seismic experiment on the order of 10 Mt to be worth drilling for detailed assessments. The mineralization is crosscut by at least two major sets of northwest-dipping reflections interpreted to dominantly be normal faults and to be responsible for much of the lowland in the Blötberget area. Moreover, these post-mineralization faults likely control the current 3D geometry of the deposits. Curved and submerged reflections interpreted from folds or later intrusions are also observed, showing the geological complexity of the study area. The seismic survey also delineates the near-surface expression of a historical tailing as a by-product of refraction static corrections, demonstrating why 3D seismic data are so valuable for both mineral exploration and mine planning applications.
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Engel, R., DJ Mcfarlane, and G. Street. "The influence of dolerite dykes on saline seeps in southwestern Australia." Soil Research 25, no. 2 (1987): 125. http://dx.doi.org/10.1071/sr9870125.
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Geophysical surveys, soil and geological mapping and hydrologic studies have been used to show an association between dolerite dykes and the occurrence of saline seeps on two catchments in southwestern Australia. The role of the dykes in the location of the saline seeps is explained and the potential contribution of routine geophysical surveys to salinity studies is highlighted. Magnetic surveys and soil and geological mapping identified dolerite dykes crossing the main drainage line of each catchment. Soil resistivity and conductivity surveys showed that these dykes are associated with saline soils. Seismic refraction surveys over these dykes indicate deeper weathering profiles. Groundwater pressures and hydraulic conductivities measured in bores across one of the weathered dykes showed that the clay saprolite formed above the dolerite is less permeable than the surrounding weathered granite. The lower permeability is probably due to the finer texture of the saprolite and/or a lower frequency of preferred flow pathways. The clay formed above the dolerite acts as a linear hydraulic barrier to lateral groundwater flow and results in the discharge of saline groundwaters into surface soils.
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Mendecki, Maciej Jan, Michał Glazer, and Mateusz Mycka. "Application of passive seismic to shallow geological structures in urban areas." Studia Quaternaria 31, no. 2 (2014): 115–22. http://dx.doi.org/10.2478/squa-2014-0012.
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AbstractTo study the shallow geological structure the Refraction Microtremor (ReMi) method was applied. This technique uses seismic noise analysis where a source of this small vibrations is the human activity e.g.: traffic, production, factories. The surveys were carried out in selected urban areas in the region of the Upper Silesian Industrial District : Sosnowiec - Pogoń , Chorzów - Chorzow Stary and Bytom - Karb. Each area is characterized by the presence of nearby roads with a very high traffic. The results of passive seismic (ReMi) were confronted with data obtained using Multichannel Analysis of Surface Waves (MASW) and resistivity imaging (RI). Seismic surveys were performed by apparatus PASI with 24 channels using geophones of 4.5Hz. The results showed that passive seismic can be satisfactorily used in such urban conditions. The shallow geological structure interpreted by seismic methods have been well-correlated with resistivity studies.
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Shive, P. N., T. Lowry, D. H. Easley, and L. E. Borgman. "Geostatistical simulation for geophysical applications—Part II: Geophysical modeling." GEOPHYSICS 55, no. 11 (1990): 1441–46. http://dx.doi.org/10.1190/1.1442791.
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A companion paper (this issue) describes a method for producing three‐dimensional simulations of physical properties for different geologic situations. Here we create a simulation for a particular case, which is a near‐surface (<80 ft deep) description of a karst environment. We simulate seismic velocity, density, resistivity, and the dielectric constant for this situation. We then conduct (in the computer) hypothetical geophysical surveys at the surface of the model. These surveys are seismic refraction, microgravity, dc resistivity, and ground‐probing radar. Physical properties appropriate for cavities are then entered in the model. Repeating the geophysical surveys over the model with cavities provides a convenient method of evaluating their potential for cavity detection. Anomalies produced by normal variations in physical properties may simulate or obscure anomalies from target features. More data about the correlation of physical properties, particularly in the horizontal directions, will be required to evaluate this problem properly.
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Ayub, Syahrial, Muhammad Zuhdi, and Joni Rokhmat. "Aplikasi Metode Seismik Refraksi dalam Menentukan Lapisan dan Tingkat Kekerasan Batuan di Bawah Permukaan Desa Medana Lombok Utara." Kappa Journal 4, no. 2 (2020): 188–96. http://dx.doi.org/10.29408/kpj.v4i2.2607.
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The seismic refraction method is one of the geophysical methods which is based on measuring the response of seismic waves in the soil that are fractured along the soil and rock layers. One of the seismic refraction method application is to determine the layers and rocks types below the surface. This study uses a geophone as a catcher for seismic waves that are emitted below the surface. The waves caught on the geophone are converted into seismic data which can be read in a seismograph. Seismic data read by seismographs are already in digital form and stored in the central unit PASI 16S24-P. The results of the data analysis concluded that below the land surface of the village of Medana, there were 3 rock layers with a thickness of the first layer 3-4 meters, the second layer 2-5 meters and the third layer 10-17 meters. The first and second layers are still in the form of soil (less compact), while the third layer is in the form of rock (compact). The level of hardness (density) will be more compact in linear to the depth, the more the depth will be the more compact the rock. The depth in the form of hard rock starts from 16 meters to 23 meters from the ground level of the village of Medana, Central Lombok.
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Schmeissner, C. M., K. T. Spikes, and D. W. Steeples. "Recording seismic reflections using rigidly interconnected geophones." GEOPHYSICS 66, no. 6 (2001): 1838–42. http://dx.doi.org/10.1190/1.1487126.
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Ultrashallow seismic reflection surveys require dense spatial sampling during data acquisition, which increases their cost. In previous efforts to find ways to reduce these costs, we connected geophones rigidly to pieces of channel iron attached to a farm implement. This method allowed us to plant the geophones in the ground quickly and automatically. The rigidly interconnected geophones used in these earlier studies detected first‐arrival energy along with minor interfering seismic modes, but they did not detect seismic reflections. To examine further the feasibility of developing rigid geophone emplacement systems to detect seismic reflections, we experimented with four pieces of channel iron, each 2.7 m long and 10 cm wide. Each segment was equipped with 18 geophones rigidly attached to the channel iron at 15‐cm intervals, and the spikes attached to all 18 geophones were pushed into the ground simultaneously. The geophones detected both refracted and reflected energy; however, no significant signal distortion or interference attributable to the rigid coupling of the geophones to the channel iron was observed in the data. The interfering seismic modes mentioned from the previous experiments were not detected, nor was any P‐wave propagation noted within the channel iron. These results show promise for automating and reducing the cost of ultrashallow seismic reflection and refraction surveys.
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Deen, Tara, and Karsten Gohl. "3‐D tomographic seismic inversion of a paleochannel system in central New South Wales, Australia." GEOPHYSICS 67, no. 5 (2002): 1364–71. http://dx.doi.org/10.1190/1.1512741.
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Buried paleochannels are of significant interest for understanding hydrological mechanisms and their potential as alluvial gold deposits. Seismic tomographic methods are a suitable solution for resolving the vertical and horizontal structure of such features. We assess a method for seismic 3‐D tomographic inversion from refraction arrivals with reflection control over a suspected paleochannel adjacent to the Wyalong gold fields in the Lachlan fold belt of central New South Wales, Australia. A standard multichannel engineering seismic recording and cable–receiver system was used on a 3‐D field geometry of multiple linear arrays. More than 3000 P‐wave first‐arrival traveltime values were inverted using a regularized inversion scheme for which simplified 2‐D models served as initial velocity–depth models for the complete 3‐D inversion. Seismic reflection arrivals provided additional depth estimates to the bedrock and compensated for a lack of refraction phases at that depth. Correlating the 3‐D seismic velocity–depth data with existing drillhole and nonseismic geophysical data resulted in a detailed structural and compositional interpretation of the paleochannel and the incised regolith. The model suggests the presence of a system of deposits from meandering channels overlying a metasedimentary bedrock formation. The general paleodrainage deposit is relatively conductive in electromagnetic surveys, indicating a potential saline storage or transport mechanism.
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Gay, Derek A., Frank D. Morgan, John A. Sogade, Yervant Vichabian, Philip Reppert, and A. E. Wharton. "Investigations of andesitic volcanic debris terrains: Part I — Geophysical." GEOPHYSICS 71, no. 1 (2006): B1—B8. http://dx.doi.org/10.1190/1.2159045.
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This article contains the findings of geophysical investigations conducted at the site of the proposed international airport at Melville Hall, Commonwealth of Dominica, West Indies. The main geophysical method used was seismic refraction; additionally, ground-penetrating radar, resistivity sounding, and resistivity tomographic imaging were performed at some of the sites, but only the results of the seismic refraction and electrical resistivity sounding contributed to the development of the model presented. Analysis of the seismic data shows a gradual increase in velocity with depth, for which a model has been determined. Ancillary models or predictions of porosity, density, and natural compaction with depth are given, based on the basic seismic model. The seismic velocity model allows an engineer with a topographic map of the area to predict the volume of rock/soil in each rippability class and to project the rate of ripping. The results of the 1D resistivity soundings strongly suggest a nearly homogeneous material with resistivity variations that can be explained by moisture and low-level lithological variations. Therefore, based on integrated seismic and resistivity results, our model is a thick ash/boulder conglomerate with velocity increasing with depth, mainly from overburden stress compaction. In other words, the material at depth is not well-cemented rock. As the overburden stress is removed, the material essentially expands and loosens to produce a lower seismic velocity, similar to present surface conditions. The soil/rock can therefore be removed with little or no ripping or blasting.
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He, Yanbin, Tianning Chen, and Xinpei Song. "Manipulation of seismic Rayleigh waves using a phase-gradient rubber metasurface." International Journal of Modern Physics B 34, no. 13 (2020): 2050142. http://dx.doi.org/10.1142/s0217979220501428.
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In this paper, a new method is proposed to manipulate seismic Rayleigh waves using phase-gradient metasurfaces. This highly compact artificial structure enables the anomalous refraction of Rayleigh waves according to the generalized Snell’s law (GSL). The soil-embedded metasurface is composed of only one column of commercial rubber blocks, which can provide an accurate phase shift to the Rayleigh wave. To verify the flexibility of this method, several metasurfaces are designed. Numerical results demonstrate that the Rayleigh waves can be focused, split, or converted into evanescent waves by using specific phase gradient configurations. The investigation also suggests the strong potential of metasurface as a smart device for shielding of seismic surface waves.
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Villalobos, Miguel, and Celso Romanel. "Seismic Response of Soft Soil Deposit Using Simplified Models." E3S Web of Conferences 92 (2019): 16008. http://dx.doi.org/10.1051/e3sconf/20199216008.
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Near surface soils can greatly influence the amplitude, duration, and frequency content of ground motions. Surveys of the damage caused by earthquakes indicates that the lowest levels of damage occur in structures founded on rock or hard soil, while most of the damage occurs usually in structures founded in soft soil sites. With the aim to understand better the seismic response of soft soils deposits, not susceptible to liquefaction, this study made a comparison between the real seismic response registered in soft soil deposit in the 2011 Tohoku earthquake (Mw=9.1), with the response predicted by a propagation analysis with the equivalent linear method using the computer program SHAKE2000 [1]. An additional comparison is made applying the simplified method of Carlton (2014), developed specifically for soft soils. The site chosen for this analysis was a soft soil deposit, with NEHRP site classification type F, monitored by the seismic station TKCH07 of the KiK-net network located in Hokaiddo, Japan. The estimated response showed and acceptable approximation with the real response, although the response calculated with SHAKE2000 predicted high levels of amplification near the natural frequencies of the soft soil deposit.
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Bergman, B., A. Tryggvason, and C. Juhlin. "Seismic tomography studies of cover thickness and near-surface bedrock velocities." GEOPHYSICS 71, no. 6 (2006): U77—U84. http://dx.doi.org/10.1190/1.2345191.
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Reflection seismic imaging of the uppermost kilometer of crystalline bedrock is an important component in site surveys for locating potential storage sites for nuclear waste in Sweden. To obtain high-quality images, refraction statics are calculated using first-break traveltimes. These first-break picks may also be used to produce tomographic velocity images of the uppermost bedrock. In an earlier study, we presented a method applicable to data sets where the vast majority of shots are located in the bedrock below the glacial deposits, or cover, typical for northern latitudes. A by-product of this method was an estimate of the cover thickness from the receiver static that was introduced to sharpen the image. We now present a modified version of this method that is applicable for sources located in or on the cover, the general situation for nuclear waste site surveys. This modified methodalso solves for 3D velocity structure and static correctionssimultaneously in the inversion process. The static corrections can then be used to estimate the cover thickness. First, we test our tomography method on synthetic data withthe shot points in the bedrock below the cover. Next, we developa strategy for the case when the sources are within the cover. Themethod is then applied to field data from five crooked-line,high-resolution reflection seismic profiles ranging in lengthfrom 2 to [Formula: see text]. The crooked-line profiles make the study 2.5dimensional regarding bedrock velocities. The cover thicknessalong the profiles varies from 0 to [Formula: see text]. Estimated thickness ofthe cover agrees well with data from boreholes drilled near theprofiles. Low-velocity zones in the uppermost bedrock generallycorrelate with locations where reflections from the stackedsections project to the surface. Thus, the method is functional,both for imaging the uppermost bedrock velocities as well as for estimating the cover thickness.
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Baziw, Erick J. "Derivation of seismic cone interval velocities utilizing forward modeling and the downhill simplex method." Canadian Geotechnical Journal 39, no. 5 (2002): 1181–92. http://dx.doi.org/10.1139/t02-061.
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The seismic cone penetration test (SCPT) has proven to be a very valuable geotechnical tool in facilitating the determination of low strain (<104%) in situ compression (P) and shear (S) wave velocities. The P- and S-wave velocities are directly related to the soil elastic constants of Poisson's ratio, shear modulus, bulk modulus, and Young's modulus. The accurate determination of P- and S-wave velocities from the recorded seismic cone time series is of paramount importance to the evaluation of reliable elastic constants. Furthermore, since the shear and compression wave velocities are squared in deriving the elastic constants, small variations in the estimated velocities can cause appreciable errors. The standard techniques implemented in deriving SCPT interval velocities rely upon obtaining reference P- and S-wave arrival times as the probe is advanced into the soil profile. By assuming a straight ray travel path from the source to the SCPT seismic receiver and calculating the relative reference arrival time differences, interval SCPT velocities are obtained. The forward modeling downhill simplex method (FMDSM) outlined in this paper offers distinct advantages over conventional SCPT velocity profile estimation methods. Some of these advantages consist of the allowance of ray path refraction, greater sophistication in interval velocity determination, incorporation of measurement weights, and meaningful interval velocity accuracy estimators.Key words: seismic cone penetration testing (SCPT), downhill simplex method (DSM), forward modeling, Fermat's principle, weighted least squares (l2 norm), cost function.
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Imposa, Sebastiano, Sabrina Grassi, Saro Di Raimondo, Graziano Patti, Giuseppe Lombardo, and Francesco Panzera. "Seismic refraction tomography surveys as a method for voids detection: an application to the archaeological park of Cava Ispica, Sicily, Italy." International Journal of Architectural Heritage 12, no. 5 (2017): 806–15. http://dx.doi.org/10.1080/15583058.2017.1419311.
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Sharafeldin, Sharafeldin M., Khalid S. Essa, Mohamed A. S. Youssef, Hakan Karsli, Zein E. Diab, and Nilgun Sayil. "Shallow geophysical techniques to investigate the groundwater table at the Great Pyramids of Giza, Egypt." Geoscientific Instrumentation, Methods and Data Systems 8, no. 1 (2019): 29–43. http://dx.doi.org/10.5194/gi-8-29-2019.
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Abstract. The near-surface groundwater aquifer that threatened the Great Pyramids of Giza, Egypt, was investigated using integrated geophysical surveys. A total of 10 electrical resistivity imaging, 26 shallow seismic refraction, and 19 ground-penetrating radar surveys were conducted in the Giza Plateau. Collected data for each method were evaluated by state-of-the art processing and modeling techniques. A three-layer model depicts the subsurface layers and better delineates the groundwater aquifer and water table elevation. The resistivity of the aquifer layer and seismic velocity vary between 40 and 80 Ωm and between 1500 and 2500 m s−1, respectively. The average water table elevation is about +15 m, which is safe for the Great Sphinx, but it is still subjected to potential hazards from the Nazlet El-Samman suburb where the water table elevation reaches 17 m. A shallower water table at the Valley Temple and the tomb of Queen Khentkawes, with a low topographic relief, represents severe hazards. It can be concluded that a perched groundwater table is detected in the elevated topography to the west and southwest that might be due to runoff and capillary seepage.
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Chen, Qiang, Sheng Zhang, Suoliang Chang, Bo Liu, Jun Liu, and Jianhui Long. "Geophysical Interpretation of a Subsurface Landslide in the Southern Qinshui Basin." Journal of Environmental and Engineering Geophysics 24, no. 3 (2019): 433–49. http://dx.doi.org/10.2113/jeeg24.3.433.
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A subsurface landslide is the key problem to a large affordable home program in the southern Qinshui Basin, China. A geophysical survey integrated with seismic refraction tomography (SRT), seismic scattered wave imaging (SSI), and electrical resistivity tomography (ERT) was performed along five profiles over the landslide body. The bedrock surface was a crucial interface, represented by a relatively high velocity, high density, and high resistivity in contrast to the unconsolidated soil and landslide material above it. Based on the most comparable geophysical features, several problems were uncovered such as a “sandwich velocity structure” in the SRT results, velocity trap in the SSI results, and rapid variations in the local topography in all three methods. Aiming to improve the comprehensive interpretation of the ERT, SRT, SSI data, the vertical gradient extremum in the ERT and SRT data and tracing the target wave group according to the velocity sensitivity in the SSI data were analyzed. Moreover, a joint interpretation of the three geophysical survey datasets as well as 32 geological wells and 73 geotechnical boreholes helped to determine one undulating bedrock surface, delineate two types of failure surface geometry (landslide surface and collapse surface), and identify three external shapes in the ex situ body (ancient river channel, landslide body and collapse body). The results showed that the integrated geophysical survey not only provided detailed evidence for the existing of landslide but also presented meaningful evidence for the sliding mechanism. These results were difficult to fully describe and to apply to understanding landslide processes. Furthermore, for near-surface landslide events, the joint interpretation of geologic, geotechnical and geophysical data was necessary to reduce problems with any single geophysical survey.
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Gusmeroli, Alessio, Roger A. Clark, Tavi Murray, Adam D. Booth, Bernd Kulessa, and Brian E. Barrett. "Seismic wave attenuation in the uppermost glacier ice of Storglaciären, Sweden." Journal of Glaciology 56, no. 196 (2010): 249–56. http://dx.doi.org/10.3189/002214310791968485.
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AbstractWe conducted seismic refraction surveys in the upper ablation area of Storglaciären, a small valley glacier located in Swedish Lapland. We estimated seismic-wave attenuation using the spectral-ratio method on the energy travelling in the uppermost ice with an average temperature of approximately −1 °C. Attenuation values were derived between 100 and 300 Hz using the P-wave quality factor, QP, the inverse of the internal friction. By assuming constant attenuation along the seismic line we obtained mean QP = 6 ± 1. We also observed that QP varies from 8 ± 1 to 5 ± 1 from the near-offset to the far-offset region of the line, respectively. Since the wave propagates deeper at far offsets, this variation is interpreted by considering the temperature profile of the study area; far-offset arrivals sampled warmer and thus more-attenuative ice. Our estimates are considerably lower than those reported for field studies in polar ice (∼500–1700 at −28°C and 50–160 at −10°C) and, hence, are supportive of laboratory experiments that show attenuation increases with rising ice temperature. Our results provide new in situ estimates of QP for glacier ice and demonstrate a valuable method for future investigations in both alpine and polar ice.
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Soupios, P., N. Papadopoulos, and A. Sarris. "Reconstructing concealed cultural remains through integrated geophysical tomographic methods." Bulletin of the Geological Society of Greece 47, no. 3 (2016): 1260. http://dx.doi.org/10.12681/bgsg.10900.
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The purpose of this work was to compare the mapping of shallow subsurface archaeological structures through Seismic Refraction Tomography (SRT), Electrical Resistivity Tomography (ERT) and Ground Penetrating Radar (GPR) methods. For achieving the goals of the project, a specific section of the archaeological site in Delphi has been surveyed through the employment of the above techniques. For the SRT survey, twenty four P-wave geophones were installed randomly in a 50 by 40 m area. Totally seventy three (73) shots were made by striking a metal plate with a sledgehammer to collect about 1752 travel-times. The pole-dipole array was employed to capture the ERT data along twenty densely spaced parallel profiles. The GPR data were collected along parallel sections with a resolution of 50 cm between the lines. The SRT and ERT field data were processed with modern tomographic inversion algorithms for the reconstruction of the 3-D velocity and resistivity models describing the buried archaeological remains and the subsurface matrix up to the depth of 5 meters below the ground surface. GPR signals were enhanced with specific filters signifying the shallow structures up to 2 meters below the ground surface. The integrated processing results indicate the existence of walls buried in a relatively uniform background soil. The outcome of this approach signifies that SRT, ERT and GPR methods can be used as a validation tool in any archaeological investigation by providing accurate tomographic subsurface models and contribute in cultural resources management.
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Ronczka, Mathias, Kristofer Hellman, Thomas Günther, Roger Wisén, and Torleif Dahlin. "Electric resistivity and seismic refraction tomography: a challenging joint underwater survey at Äspö Hard Rock Laboratory." Solid Earth 8, no. 3 (2017): 671–82. http://dx.doi.org/10.5194/se-8-671-2017.
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Abstract. Tunnelling below water passages is a challenging task in terms of planning, pre-investigation and construction. Fracture zones in the underlying bedrock lead to low rock quality and thus reduced stability. For natural reasons, they tend to be more frequent at water passages. Ground investigations that provide information on the subsurface are necessary prior to the construction phase, but these can be logistically difficult. Geophysics can help close the gaps between local point information by producing subsurface images. An approach that combines seismic refraction tomography and electrical resistivity tomography has been tested at the Äspö Hard Rock Laboratory (HRL). The aim was to detect fracture zones in a well-known but logistically challenging area from a measuring perspective. The presented surveys cover a water passage along part of a tunnel that connects surface facilities with an underground test laboratory. The tunnel is approximately 100 m below and 20 m east of the survey line and gives evidence for one major and several minor fracture zones. The geological and general test site conditions, e.g. with strong power line noise from the nearby nuclear power plant, are challenging for geophysical measurements. Co-located positions for seismic and ERT sensors and source positions are used on the 450 m underwater section of the 700 m profile. Because of a large transition zone that appeared in the ERT result and the missing coverage of the seismic data, fracture zones at the southern and northern parts of the underwater passage cannot be detected by separated inversion. Synthetic studies show that significant three-dimensional (3-D) artefacts occur in the ERT model that even exceed the positioning errors of underwater electrodes. The model coverage is closely connected to the resolution and can be used to display the model uncertainty by introducing thresholds to fade-out regions of medium and low resolution. A structural coupling cooperative inversion approach is able to image the northern fracture zone successfully. In addition, previously unknown sedimentary deposits with a significantly large thickness are detected in the otherwise unusually well-documented geological environment. The results significantly improve the imaging of some geologic features, which would have been undetected or misinterpreted otherwise, and combines the images by means of cluster analysis into a conceptual subsurface model.
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Yokoi, Toshiaki. "Numerical study on the generation of downgoing S‐waves by a vertical force acting close to a step‐like topography." GEOPHYSICS 61, no. 1 (1996): 192–201. http://dx.doi.org/10.1190/1.1443939.
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I present detailed numerical experiments on a recently proposed S‐wave generation method and show the excitation characteristics of the downgoing S‐wave caused by a vertical impact acting close to a step‐like topography. The geophysicists’ group of Akita University recently studied and confirmed this phenomenon by in‐situ measurements and named it the “pit effect.” The numerical simulation is performed in 2-D space by the indirect boundary‐element method using the Green’s function for a homogeneous unbounded medium. The results show that the pit effect is a practical S‐wave generator vertical seismic profiling (VSP) and refraction surveys. The generation of a vertical downgoing S‐wave does not require any special machinery, so the pit effect can be used in many situations and especially in remote areas and difficult enviroments such as swamps and steep mountain ranges.
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Le Ngal, Nwai, Subagyo Pramumijoyo, Iman Satyarno, Kirbani Sri Brotopuspito, Junji Kiyono, and Eddy Hartantyo. "Multi-channel analysis of surface wave method for geotechnical site characterization in Yogyakarta, Indonesia." E3S Web of Conferences 76 (2019): 03006. http://dx.doi.org/10.1051/e3sconf/20197603006.
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On May 27th 2006, Yogyakarta earthquake happened with 6.3 Mw. It was causing widespread destruction and loss of life and property. The average shear wave velocity to 30 m (Vs30) is useful parameter for classifying sites to predict their potential to amplify seismic shaking (Boore, 2004) [1]. Shear wave velocity is one of the most influential factors of the ground motion. The average shear wave velocity for the top 30 m of soil is referred to as Vs30. In this study, the Vs30 values were calculated by using multichannel analysis of surface waves (MASW) method. The Multichannel Analysis of Surface Waves (MASW) method was introduced by Park et al. (1999). Multi-channel Analysis of Surface Waves (MASW) is non-invasive method of estimating the shear-wave velocity profile. It utilizes the dispersive properties of Rayleigh waves for imaging the subsurface layers. MASW surveys can be divided into active and passive surveys. In active MASW method, surface waves can be easily generated by an impulsive source like a hammer, sledge hammer, weight drops, accelerated weight drops and explosive. Seismic measurements were carried out 44 locations in Yogyakarta province, in Indonesia. The dispersion data of the recorded Rayleigh waves were processed by using Seisimager software to obtain shear wave velocity profiles of the studied area. The average shear wave velocities of the soil obtained are ranging from 200 ms-1 to 988 ms-1, respectively.
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Khaheshi Banab, Kasgin, and Dariush Motazedian. "On the Efficiency of the Multi-Channel Analysis of Surface Wave Method for Shallow and Semi-Deep Loose Soil Layers." International Journal of Geophysics 2010 (2010): 1–13. http://dx.doi.org/10.1155/2010/403016.
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The multi-channel analysis of surface waves (MASWs) method was used to obtain the shear wave velocity variations through near surface (depth < 30 m) and semi-deep (30 m < depth < 100 m) soil layers in the city of Ottawa, Canada. Sixteen sites were examined to evaluate the capability of the active and passive MASW methods for cases where the shear wave velocity(Vs)contrast between very loose soil (Vs< 200 m/s) and very firm bedrock (Vs> 2,300 m/s) is very large. The MASW velocity results compared with those of other geophysical approaches, such as seismic reflection/refraction methods and borehole data, where available, mostly confirming the capability of the MASW method to distinguish the high shear wave velocity contrast in the study area. We have found that, of the inversion procedures of MASW data, the random search inversion technique provides better results than the analytical generalized inversion method.
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Palacky, G. J., and L. E. Stephens. "Detection of subbottom ice‐bonded permafrost on the Canadian Beaufort Shelf by ground electromagnetic measurements." GEOPHYSICS 57, no. 11 (1992): 1419–27. http://dx.doi.org/10.1190/1.1443209.
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Accurate knowledge of the location of subbottom ice‐bonded permafrost is essential in planning major infrastructure projects such as pipelines in the Arctic. A combination of refraction and shallow reflection seismic surveys and drilling has been considered the most effective means of permafrost detection in offshore environments. Field experiments recently carried out on the Beaufort Shelf by the Geological Survey of Canada indicate that multifrequency horizontal‐loop electromagnetic (HLEM) measurements are a fast and cost‐effective alternative. During test surveys, 60 to 80 soundings were completed in a day. Analysis of HLEM field data shows that a four‐layer model is appropriate for the local geologic conditions. The first layer in the model, sea ice, is highly resistive (5000 Ω ⋅ m). The second layer consists of seawater and seawater‐saturated sediments (estimated resistivity 1 Ω ⋅ m). Because their true resistivities are not significantly different, it was not possible to separate the two highly conductive layers by inversion. The target of the survey, subbottom ice‐bonded permafrost, was the third layer in the section (resistivity 5000 Ω ⋅ m). The bottom layer is formed by unfrozen sediments (average resistivity 2 Ω ⋅ m). Comparison with seismic and drilling results indicates that detection of ice‐bonded permafrost by the HLEM method is reliable; the outlines of its upper boundary given by seismic and HLEM measurements are in good agreement. At the only borehole available, unconstrained inversion of HLEM data provided an accurate estimate of permafrost depth and thickness, but there is not enough drilling information to objectively assess the reliability of the technique.
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Chen, Tuo. "Seismic response analysis of loess site under far-field bedrock ground motion of the Wenchuan earthquake." PLOS ONE 16, no. 7 (2021): e0254871. http://dx.doi.org/10.1371/journal.pone.0254871.
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In this paper, considering the far-field seismic input, an accelerogram recorded in the bedrock at Wuquan Mountain in Lanzhou city during the 2008 Wenchuan Ms8.0 earthquake was selected, and numerical dynamic analyses were conducted. The one-dimensional equivalent linear method was implemented to estimate the ground motion effects in the loess regions. Thereafter, slope topographic effects on ground motion were studied by applying the dynamic finite-element method. The results revealed the relationship between the PGA amplification coefficients and the soil layer thickness, which confirmed that the dynamic response of the sites had obvious nonlinear characteristics. The results also showed that there was an obvious difference in the dynamic magnification factor between the short-period and long-period structures. Moreover, it was found that the amplification coefficient of the observation point at the free surface was greater than the point inside the soil at the same depth, which mainly occurred in the upper slope. Through this study, the quantitative assessment of ground motion effects in loess regions can be approximately estimated, and the amplification mechanism of the far-field ground motion mechanism can be further explained. In addition to the refraction and reflection theory of seismic waves, the resonance phenomenon may help explain the slope topographic effect through spectrum analysis.
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Huang, Bo, Jiachen Guo, Kailong Liao, and Yu Zhao. "Fragility Analysis of RC Frame Structures Subjected to Obliquely Incident Seismic Waves." Sustainability 13, no. 3 (2021): 1108. http://dx.doi.org/10.3390/su13031108.
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Obliquely incident seismic waves have been habitually overlooked in fragility analysis. In this paper, a new approach to solving the equivalent loads on the infinite element boundary due to obliquely incident seismic waves is proposed. Based on the site conditions and structural characteristics in the Jiaxing area, the seismic response of a multi-story reinforced concrete (RC) frame structure has been fully investigated through the finite element method. Under obliquely incident SV waves (shear wave in the vertical x-z plane), the distribution of internal forces on the structure in the case of homogeneous foundation soil is significantly asymmetrical. Among the 3 obliquely incident angles investigated in this paper, the maximum inter-story displacement is smallest when the incident angle is 20° and largest when the angle equals 30°. For the structural fragility, the exceedance probability at each structural damage level is smallest when the incident reflection angle is 20° and largest when the angle equals 30°. When the structure is located in the silty valley, the influence of oblique incidence is attenuated and there is no obvious stress asymmetry on the structure due to the refraction of seismic waves on the interface.
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Gras, Clàudia, Daniel Dagnino, Clara Estela Jiménez-Tejero, Adrià Meléndez, Valentí Sallarès, and César R. Ranero. "Full-waveform inversion of short-offset, band-limited seismic data in the Alboran Basin (SE Iberia)." Solid Earth 10, no. 6 (2019): 1833–55. http://dx.doi.org/10.5194/se-10-1833-2019.
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Abstract. We present a high-resolution P-wave velocity model of the sedimentary cover and the uppermost basement to ∼3 km depth obtained by full-waveform inversion of multichannel seismic data acquired with a 6 km long streamer in the Alboran Sea (SE Iberia). The inherent non-linearity of the method, especially for short-offset, band-limited seismic data as this one, is circumvented by applying a data processing or modelling sequence consisting of three steps: (1) data re-datuming by back-propagation of the recorded seismograms to the seafloor; (2) joint refraction and reflection travel-time tomography combining the original and the re-datumed shot gathers; and (3) full-waveform inversion of the original shot gathers using the model obtained by travel-time tomography as initial reference. The final velocity model shows a number of geological structures that cannot be identified in the travel-time tomography models or easily interpreted from seismic reflection images alone. A sharp strong velocity contrast accurately defines the geometry of the top of the basement. Several low-velocity zones that may correspond to the abrupt velocity change across steeply dipping normal faults are observed at the flanks of the basin. A 200–300 m thick, high-velocity layer embedded within lower-velocity sediment may correspond to evaporites deposited during the Messinian crisis. The results confirm that the combination of data re-datuming and joint refraction and reflection travel-time inversion provides reference models that are accurate enough to apply full-waveform inversion to relatively short offset streamer data in deep-water settings starting at a field-data standard low-frequency content of 6 Hz.
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Hanafy, S., and S. A. al Hagrey. "Ground-penetrating radar tomography for soil-moisture heterogeneity." GEOPHYSICS 71, no. 1 (2006): K9—K18. http://dx.doi.org/10.1190/1.2159052.
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Many ground-penetrating radar (GPR) studies incorporate tomographic methods that use straight raypaths for direct model reconstruction, which is unrealistic for media with gradually changing petrophysics. Ray-bending algorithms can sometimes lead to unreliable resolution, especially at interfaces of abrupt dielectric changes. We present an improved GPR tomography technique based on a combination of seismic tomographic methods and a finite-difference solution of the eikonal equation. Our inversion algorithm uses velocity gradient zones and bending rays that represent realistic geology in the subsurface. We tested the technique on theoretical and experimental models with anomalous bodies of varying saturations and velocity and applied it to data from a GPR field experiment that analyzed the root zones of trees. Synthetic results showed that the resolution of our technique is better than that of published methods, especially for local anomalies with sharp velocity contacts. Our laboratory experiments consisted of four objects buried in sand with various water saturations. The GPR tomogram could map the objects and determine their degree of saturation. The velocities are compatible with those of the complex refraction index method; their relationship to the water content fits a previously published empirical equation. Our original field experiment around a poplar tree could map the heterogeneous subsurface and distinguish a central low velocity beneath the tree from the peripheral negative anomaly of a refill. This zone reflects the whole root zone and is caused by its bulk water content of both the organic root network and its surrounding soils.
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Prostov, Sergey, Evgeniy Shabanov, Michail Sokolov, and Musa Shabdanov. "Improving Earthquake Resistance of Structures by Injection Consolidation of Earth Foundations." E3S Web of Conferences 174 (2020): 01018. http://dx.doi.org/10.1051/e3sconf/202017401018.
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Based on the analysis of the results of field experiments, recommendations were developed on increasing the earthquake resistance of soil foundations of buildings and structures at the Krasnobrodsky coal open-pit mine, providing conditions for an uninterrupted and safe technological process of minerals extraction and transportation. As a result of research carried out at a pilot test site by the method of seismic sounding using the refraction technique, scientific and practical results were obtained. It has been experimentally proved that compacting soils with cement-sand mortar allows us to improve their deformation properties, which leads to an increase in the earthquake resistance of structures. The seismicity of the soil foundation of the enrichment complex of inclined separation was calculated on the basis of the performed simulation of deformation processes in the consolidated foundation of the structure in a critical state. The studies have found out that when weakened soils are compacted under the supports of the galleries of the structure and after the artificial foundation has gained strength, seismicity decreased from 7 to 6 points.
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Gosar, Andrej. "Study on the applicability of the microtremor HVSR method to support seismic microzonation in the town of Idrija (W Slovenia)." Natural Hazards and Earth System Sciences 17, no. 6 (2017): 925–37. http://dx.doi.org/10.5194/nhess-17-925-2017.
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Abstract. The town of Idrija is located in an area with an increased seismic hazard in W Slovenia and is partly built on alluvial sediments or artificial mining and smelting deposits which can amplify seismic ground motion. There is a need to prepare a comprehensive seismic microzonation in the near future to support seismic hazard and risk assessment. To study the applicability of the microtremor horizontal-to-vertical spectral ratio (HVSR) method for this purpose, 70 free-field microtremor measurements were performed in a town area of 0.8 km2 with 50–200 m spacing between the points. The HVSR analysis has shown that it is possible to derive the sediments' resonance frequency at 48 points. With the remaining one third of the measurements, nearly flat HVSR curves were obtained, indicating a small or negligible impedance contrast with the seismological bedrock. The isofrequency (a range of 2.5–19.5 Hz) and the HVSR peak amplitude (a range of 3–6, with a few larger values) maps were prepared using the natural neighbor interpolation algorithm and compared with the geological map and the map of artificial deposits. Surprisingly no clear correlation was found between the distribution of resonance frequencies or peak amplitudes and the known extent of the supposed soft sediments or deposits. This can be explained by relatively well-compacted and rather stiff deposits and the complex geometry of sedimentary bodies. However, at several individual locations it was possible to correlate the shape and amplitude of the HVSR curve with the known geological structure and prominent site effects were established in different places. In given conditions (very limited free space and a high level of noise) it would be difficult to perform an active seismic refraction or MASW measurements to investigate the S-wave velocity profiles and the thickness of sediments in detail, which would be representative enough for microzonation purposes. The importance of the microtremor method is therefore even greater, because it enables a direct estimation of the resonance frequency without knowing the internal structure and physical properties of the shallow subsurface. The results of this study can be directly used in analyses of the possible occurrence of soil–structure resonance of individual buildings, including important cultural heritage mining and other structures protected by UNESCO. Another application of the derived free-field isofrequency map is to support soil classification according to the recent trends in building codes and to calibrate Vs profiles obtained from the microtremor array or geophysical measurements.
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Ivanov, Julian, Richard D. Miller, Daniel Feigenbaum, Sarah L. C. Morton, Shelby L. Peterie, and Joseph B. Dunbar. "Revisiting levees in southern Texas using Love-wave multichannel analysis of surface waves with the high-resolution linear Radon transform." Interpretation 5, no. 3 (2017): T287—T298. http://dx.doi.org/10.1190/int-2016-0044.1.
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Shear-wave velocities were estimated at a levee site by inverting Love waves using the multichannel analysis of surface waves (MASW) method augmented with the high-resolution linear Radon transform (HRLRT). The selected site was one of five levee sites in southern Texas chosen for the evaluation of several seismic data-analysis techniques readily available in 2004. The methods included P- and S-wave refraction tomography, Rayleigh- and Love-wave surface-wave analysis using MASW, and P- and S-wave cross-levee tomography. The results from the 2004 analysis revealed that although the P-wave methods provided reasonable and stable results, the S-wave methods produced surprisingly inconsistent shear-wave velocity [Formula: see text] estimates and trends compared with previous studies and borehole investigations. In addition, the Rayleigh-wave MASW method was nearly useless within the levee due to the sparsity of high frequencies in fundamental-mode surface waves and complexities associated with inverting higher modes. This prevented any reliable [Formula: see text] estimates for the levee core. Recent advances in methodology, such as the HRLRT for obtaining higher resolution dispersion-curve images with the MASW method and the use of Love-wave inversion routines specific to Love waves as part of the MASW method, provided the motivation to extend the 2004 original study by using horizontal-component seismic data for characterizing the geologic properties of levees. Contributions from the above-mentioned techniques were instrumental in obtaining [Formula: see text] estimates from within these levees that were very comparable with the measured borehole samples. A Love-wave approach can be a viable alternative to Rayleigh-wave MASW surveys at sites where complications associated with material or levee geometries inhibit reliable [Formula: see text] results from Rayleigh waves.
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Tran, Khiem T., and Justin Sperry. "Application of 2D full-waveform tomography on land-streamer data for assessment of roadway subsidence." GEOPHYSICS 83, no. 3 (2018): EN1—EN11. http://dx.doi.org/10.1190/geo2016-0550.1.
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Roadways are key components of the modern transportation system. Therefore, assessment of roadway subsidence is critical to the health and safety of the traveling public. Existing seismic refraction and waveform tomography methods can be used for subsidence evaluation; however, the data acquisition time is significant because they require multiple source impacts (shots) along a test line. To mitigate the negative impact caused by closing the traffic flow under seismic testing, a land-streamer seismic testing system and waveform analysis are developed. An existing 2D Gauss-Newton full-waveform inversion (FWI) method is extended for analysis of the land-streamer waveform data. The main advantage of using land-streamer waveform data is that geophones are not coupled to test materials and source-receiver offsets are fixed; thus, the whole test system can be moved along the roadway quickly for data acquisition. To demonstrate the effectiveness of land-streamer waveform data, the FWI method was tested on synthetic and field data sets. The synthetic result reveals that buried voids can be well-characterized by the land-streamer waveform analysis. Field data were collected on asphalt pavement using a 24 channel land streamer and a propelled energy generator to induce seismic wave energy. The test system was towed by a pickup truck along a roadway with an on-going subsidence (repaired sinkhole). The data were collected over 277.5 m distance at a 3 m interval, and the total data acquisition time was approximately 1 h. The field data result indicates that the waveform analysis was able to delineate low-velocity soil zones and laterally variable bedrock. The FWI results are also compared with multichannel analysis of surface wave (MASW) results. The 2D [Formula: see text] profiles from the FWI and MASW methods are consistent; however, the FWI method provides more detailed information ([Formula: see text] of [Formula: see text] cells) of low-velocity anomalies for assessment of roadway subsidence.
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Darvasi, Yaniv, and Amotz Agnon. "Calibrating a new attenuation curve for the Dead Sea region using surface wave dispersion surveys in sites damaged by the 1927 Jericho earthquake." Solid Earth 10, no. 2 (2019): 379–90. http://dx.doi.org/10.5194/se-10-379-2019.
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Abstract. Instrumental strong motion data are not common around the Dead Sea region. Therefore, calibrating a new attenuation equation is a considerable challenge. However, the Holy Land has a remarkable historical archive, attesting to numerous regional and local earthquakes. Combining the historical record with new seismic measurements will improve the regional equation. On 11 July 1927, a rupture, in the crust in proximity to the northern Dead Sea, generated a moderate 6.2 ML earthquake. Up to 500 people were killed, and extensive destruction was recorded, even as far as 150 km from the focus. We consider local near-surface properties, in particular, the shear-wave velocity, as an amplification factor. Where the shear-wave velocity is low, the seismic intensity far from the focus would likely be greater than expected from a standard attenuation curve. In this work, we used the multichannel analysis of surface waves (MASW) method to estimate seismic wave velocity at anomalous sites in Israel in order to calibrate a new attenuation equation for the Dead Sea region. Our new attenuation equation contains a term which quantifies only lithological effects, while factors such as building quality, foundation depth, topography, earthquake directivity, type of fault, etc. remain out of our scope. Nonetheless, about 60 % of the measured anomalous sites fit expectations; therefore, this new ground-motion prediction equation (GMPE) is statistically better than the old ones. From our local point of view, this is the first time that integration of the 1927 historical data and modern shear-wave velocity profile measurements improved the attenuation equation (sometimes referred to as the attenuation relation) for the Dead Sea region. In the wider context, regions of low-to-moderate seismicity should use macroseismic earthquake data, together with modern measurements, in order to better estimate the peak ground acceleration or the seismic intensities to be caused by future earthquakes. This integration will conceivably lead to a better mitigation of damage from future earthquakes and should improve maps of seismic hazard.