scholarly journals A comparison of seismic and radar methods to establish the thickness and density of glacier snow cover

2013 ◽  
Vol 54 (64) ◽  
pp. 73-82 ◽  
Author(s):  
Adam D. Booth ◽  
Andrew Mercer ◽  
Roger Clark ◽  
Tavi Murray ◽  
Peter Jansson ◽  
...  
Keyword(s):  
Lower Layer ◽  
Effective Means ◽  
Seismic Refraction ◽  
Geophysical Methods ◽  
Ground Truth ◽  
Snow Layer ◽  
Refraction Seismic ◽  
Geophysical Surveys ◽  
Glacier Ice ◽  
Snow Thickness

AbstractWe show that geophysical methods offer an effective means of quantifying snow thickness and density. Opportunistic (efficient but non-optimized) seismic refraction and ground-penetrating radar (GPR) surveys were performed on Storglaciären, Sweden, co-located with a snow pit that shows the snowpack to be 1.73 m thick, with density increasing from ∼120 to ∼500 kg m–3(with a +50 kg m–3anomaly between 0.73 and 0.83 m depth). Depths estimated for two detectable GPR reflectors, 0.76 ±0.02 and 1.71 ± 0.03 m, correlate extremely well with ground-truth observations. Refraction seismic predicts an interface at 1.90 ± 0.31 m depth, with a refraction velocity (3730 ± 190 ms–1) indicative of underlying glacier ice. For density estimates, several standard velocity-density relationships are trialled. In the best case, GPR delivers an excellent density estimate for the upper snow layer (observed = 321 ± 74 kg m–3, estimated = 319 ± 10 kgm–3) but overestimates the density of the lower layer by 20%. Refraction seismic delivers a bulk density of 404 ±22 kgm–3compared with a ground-truth average of 356 ± 22 kg m–3. We suggest that geophysical surveys are an effective complement to mass-balance measurements (particularly for controlling estimates of snow thickness between pits) but should always be validated against ground-truth observations.

Current Land and Waterborne Geophysical Methods for Guiding Horizontal Directional Drilling and Trenching Along Pipeline Right-of-Ways

2016 ◽  
Author(s):  
Paul Bauman ◽  
Alastair McClymont ◽  
Landon Woods ◽  
Erin Ernst
Keyword(s):  
Seismic Refraction ◽  
Geophysical Methods ◽  
Cost Effective ◽  
The Arctic ◽  
Directional Drilling ◽  
Borehole Geophysics ◽  
Discontinuous Permafrost ◽  
Refraction Seismic ◽  
Geotechnical Investigations ◽  
Geophysical Surveys

In Western Canada, oil and natural gas pipeline projects are being considered that will move hydrocarbons from the Prairie Provinces and British Columbia, to the Pacific Ocean, the Atlantic, and even potentially the Arctic. Along the proposed right-of-ways, the pipeline engineers will encounter challenging and varied terrain, including discontinuous permafrost, creek and river crossings, glaciomarine clays, thick muskeg, and other subsurface conditions that require specialized engineering planning in advance of construction. Geophysical surveys, in support of geotechnical investigations, provide continuous subsurface information to help inform design challenges associated with the many terrain challenges. Some geophysical surveys to be considered include electrical resistivity tomography (ERT), induced polarization (IP), seismic refraction, seismic reflection, multi-channel analysis of surface waves (MASW), ground penetrating radar (GPR), and borehole geophysics. Typically, a combination of several geophysical surveys along with drilling information, are optimal for the cost-effective site characterization of problematic segments of proposed pipeline right-of-ways.

Integration of Multi-geophysical Approaches to Identify Potential Pathways of Heavy Metals Contamination - A Case Study in Zeida, Morocco

2020 ◽  
Vol 25 (3) ◽  
pp. 415-423
Author(s):  
Ahmed Lachhab ◽  
El Mehdi Benyassine ◽  
Mohamed Rouai ◽  
Abdelilah Dekayir ◽  
Jean C. Parisot ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Seismic Velocity ◽  
Seismic Refraction ◽  
Geophysical Methods ◽  
Low Frequency ◽  
Electrical Current ◽  
P Wave ◽  
Low Resistivity ◽  
Refraction Tomography ◽  
Geophysical Surveys

The tailings of Zeida's abandoned mine are found near the city of Midelt, in the middle of the high Moulouya watershed between the Middle and the High Atlas of Morocco. The tailings occupy an area of about 100 ha and are stored either in large mining pit lakes with clay-marl substratum or directly on a heavily fractured granite bedrock. The high contents of lead and arsenic in these tailings have transformed them into sources of pollution that disperse by wind, runoff, and seepage to the aquifer through faults and fractures. In this work, the main goal is to identify the pathways of contaminated water with heavy metals and arsenic to the local aquifers, water ponds, and Moulouya River. For this reason, geophysical surveys including electrical resistivity tomography (ERT), seismic refraction tomography (SRT) and very low-frequency electromagnetic (VLF-EM) methods were carried out over the tailings, and directly on the substratum outside the tailings. The result obtained from combining these methods has shown that pollutants were funneled through fractures, faults, and subsurface paleochannels and contaminated the hydrological system connecting groundwater, ponds, and the river. The ERT profiles have successfully shown the location of fractures, some of which extend throughout the upper formation to depths reaching the granite. The ERT was not successful in identifying fractures directly beneath the tailings due to their low resistivity which inhibits electrical current from propagating deeper. The seismic refraction surveys have provided valuable details on the local geology, and clearly identified the thickness of the tailings and explicitly marked the boundary between the Triassic formation and the granite. It also aided in the identification of paleochannels. The tailings materials were easily identified by both their low resistivity and low P-wave velocity values. Also, both resistivity and seismic velocity values rapidly increased beneath the tailings due to the compaction of the material and lack of moisture and have proven to be effective in identifying the upper limit of the granite. Faults were found to lie along the bottom of paleochannels, which suggest that the locations of these channels were caused by these same faults. The VLF-EM surveys have shown tilt angle anomalies over fractured areas which were also evinced by low resistivity area in ERT profiles. Finally, this study showed that the three geophysical methods were complementary and in good agreement in revealing the pathways of contamination from the tailings to the local aquifer, nearby ponds and Moulouya River.

Application of geophysical methods for the investigation of the large gravitational mass movement of Séchilienne, France

2005 ◽  
Vol 42 (4) ◽  
pp. 1105-1115 ◽  
Author(s):  
O Meric ◽  
S Garambois ◽  
D Jongmans ◽  
M Wathelet ◽  
J L Chatelain ◽  
...  
Keyword(s):  
Rock Mass ◽  
Mass Movement ◽  
Seismic Refraction ◽  
Geophysical Methods ◽  
Time Lapse ◽  
Gravitational Mass ◽  
Electrical Tomography ◽  
Refraction Tomography ◽  
Geophysical Surveys ◽  
Geophysical Techniques

Several geophysical techniques (electromagnetic profiling, electrical tomography, seismic refraction tomography, and spontaneous potential and seismic noise measurement) were applied in the investigation of the large gravitational mass movement of Séchilienne. France. The aim of this study was to test the ability of these methods to characterize and delineate the rock mass affected by this complex movement in mica schists, whose lateral and vertical limits are still uncertain. A major observation of this study is that all the zones strongly deformed (previously and at present) by the movement are characterized by high electrical resistivity values (>3 kΩ·m), in contrast to the undisturbed mass, which exhibits resistivity values between a few hundred and 1 kΩ·m. As shown by the surface observations and the seismic results, this resistivity increase is due to a high degree of fracturing associated with the creation of air-filled voids inside the mass. Other geophysical techniques were tested along a horizontal transect through the movement, and an outstanding coherency appeared between the geophysical anomalies and the displacement rate curve. These preliminary results illustrate the benefits of combined geophysical techniques for characterizing the rock mass involved in the movement. Results also suggest that monitoring the evolution of the rock mass movement with time-lapse geophysical surveys could be beneficial.Key words: gravitational movement, geophysical methods, Séchilienne.

The use of geophysical prospecting for imaging active faults in the Roer Graben, Belgium

Geophysics ◽  
2001 ◽  
Vol 66 (1) ◽  
pp. 78-89 ◽  
Author(s):  
Donat Demanet ◽  
François Renardy ◽  
Kris Vanneste ◽  
Denis Jongmans ◽  
Thierry Camelbeeck ◽  
...  
Keyword(s):  
High Resolution ◽  
Physical Properties ◽  
Fault Zone ◽  
Geophysical Methods ◽  
Depth Range ◽  
Electrical Tomography ◽  
Reflection Seismic ◽  
Refraction Seismic ◽  
Geophysical Surveys ◽  
Geophysical Techniques

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.

GEOPHYSICAL METHODS ADAPTED TO HIGHWAY ENGINEERING PROBLEMS

Geophysics ◽  
1952 ◽  
Vol 17 (3) ◽  
pp. 505-530 ◽  
Author(s):  
R. Woodward Moore
Keyword(s):  
Seismic Refraction ◽  
Geophysical Methods ◽  
Engineering Structures ◽  
Highway Engineering ◽  
Earth Resistivity ◽  
The Earth ◽  
Ore Bodies ◽  
Geophysical Surveys ◽  
Engineering Problems ◽  
Test Use

Of the several geophysical methods used in exploration for oil and useful ore bodies, the earth‐resistivity and seismic‐refraction tests have been found to be the most adaptable to the shallow tests generally required in highway construction work. Of these, the earth‐resistivity test is the faster and has a wider range of application to highway problems than does the seismic test. Use of both methods of tests in subsurface explorations for engineering structures is expanding. The paper cites a growing need for a more thorough subsurface investigation of all engineering structure sites and gives examples of field data obtained by the Bureau of Public Roads when making preliminary geophysical surveys of proposed highway locations or structure sites. The economic aspects and the advantages and limitations of the two methods of test are discussed with particular reference to their application to highway engineering problems.

Upscaling of geophysical measurements: A methodology for the estimation of the total ground ice content at two study sites in the dry Andes of Chile and Argentina

2020 ◽  
Author(s):  
Tamara Mathys ◽  
Christin Hilbich ◽  
Cassandra E.M. Koenig ◽  
Lukas Arenson ◽  
Christian Hauck
Keyword(s):  
Hydrological Cycle ◽  
Spatial Scales ◽  
Geophysical Methods ◽  
Central Andes ◽  
Permafrost Degradation ◽  
Rock Glacier ◽  
Ground Ice ◽  
Refraction Seismic ◽  
Geophysical Surveys ◽  
Ice Content

<p>With climate change and the associated continuing recession of glaciers, water security, especially in regions depending on the water supply from glaciers, is threatened. In this context, the understanding of permafrost distribution and its degradation is of increasing importance as it is currently debated whether ground ice can be considered as a significant water reservoir and as an alternative resource of fresh water that could potentially moderate water scarcity during dry seasons in the future. Thus, there is a pressing need to better understand how much water is stored as ground ice in areas with extensive permafrost occurrence and how meltwater from permafrost degradation may contribute to the hydrological cycle in the region.</p><p>Although permafrost and permafrost landforms in the Central Andes are considered to be abundant and well developed, the data is scarce and understanding of the Andean cryosphere lacking, especially in areas devoid of glaciers and rock glaciers.</p><p>In the absence of boreholes and test pits, geophysical investigations are a feasible and cost-effective technique to detect ground ice occurrences within a variety of landforms and substrates. In addition to the geophysical surveys themselves, upscaling techniques are needed to estimate ground ice content, and thereby future water resources, on larger spatial scales. To contribute to reducing the data scarcity regarding ground ice content in the Central Andes, this study focuses on the permafrost distribution and the ground ice content (and its water equivalent) of two catchments in the semi-arid Andes of Chile and Argentina. Geophysical methods (Electrical Resistivity Tomography, ERT and Refraction Seismic Tomography, RST) were used to detect and quantify ground ice in the study regions in the framework of environmental impact assessments in mining areas. Where available, ERT and RST measurements were quantitatively combined to estimate the volumetric ground ice content using the Four Phase Model (Hauck et al., 2011). Furthermore, we developed one of the first methodologies for the upscaling of these geophysical-based ground ice quantifications to an entire catchment in order to estimate the total ground ice volume in the study areas.</p><p>In this contribution we will present the geophysical data, the upscaling methodology used to estimate total ground ice content (and water equivalent) of permafrost areas, and some first estimates of total ground ice content in rock glacier and rock glacier free areas and compare them to conventional estimates using remotely sensed data.</p><p> </p><p>Hauck, C., Böttcher, M., and Maurer, H. (2011). A new model for estimating subsurface ice content based on combined electrical and seismic datasets, The Cryosphere, 5: 453-468.</p>

Efficiency Of Integrated Seismic Methods Approach To Near-Surface Characterization

2020 ◽  
Author(s):  
Irena Gjorgjeska ◽  
Vlatko Sheshov ◽  
Kemal Edip ◽  
Dragi Dojchinovski
Keyword(s):  
Surface Characterization ◽  
Seismic Refraction ◽  
Geophysical Methods ◽  
Cost Effective ◽  
Integrated Approach ◽  
Image Resolution ◽  
Future Research ◽  
Near Surface ◽  
Seismic Methods ◽  
Refraction Seismic

<p>Surface seismic methods are among the most popular, widely accepted, geophysical methods for near-surface characterization. The most practical and effective way to perform in-situ measurements and data processing using different seismic methods as are seismic refraction, seismic reflection and MASW method in an integrated approach is presented in this paper. Each method has some advantages and limitations, but their application in an integrated approach provides higher accuracy in subsurface modeling. The same seismic equipment and, in most of the cases, the same acquisition parameters were used, enabling time and cost effective survey for subsurface characterization. The choice of these parameters was not random. Experimental research by use of the above-mentioned seismic methods was carried out in a long period in order to define the optimal parameters for successful application of an integrated technique in future research. During this survey, particular attention was paid to the influence of the acquisition parameters on the dispersion image resolution in the MASW surveys and extraction of an effective dispersion curve.</p><p>The results of the performed surveys at characteristic locations in R. North Macedonia are presented to show the efficiency of the combined methods approach.</p>

scholarly journals Merge-Optimization Method of Combined Tomography of Seismic Refraction and Resistivity Data

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Andy A. Bery
Keyword(s):  
High Resolution ◽  
Seismic Refraction ◽  
Geophysical Methods ◽  
Optimization Method ◽  
Detailed Knowledge ◽  
Data Sets ◽  
Geophysical Surveys ◽  
Data Points ◽  
Geophysical Imaging ◽  
Seismic Refraction Data

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%.

scholarly journals NON-DESTRUCTIVE INVESTIGATION ON SMALL EARTH DAMS USING GEOPHYSICAL METHODS: SEISMIC SURFACE WAVE MULTICHANNEL ANALYSIS (MASW) AND S-WAVE REFRACTION SEISMIC METHODS

2020 ◽  
Vol 38 (1) ◽  
pp. 5
Author(s):  
Leonides Guireli Netto ◽  
Otavio Coaracy Brasil Gandolfo ◽  
Walter Malagutti Filho ◽  
João Carlos Dourado
Keyword(s):  
Seismic Refraction ◽  
Geophysical Methods ◽  
Internal Flow ◽  
Sao Paulo ◽  
São Paulo ◽  
Earth Dams ◽  
S Wave ◽  
Multichannel Analysis ◽  
Refraction Seismic ◽  
Non Destructive

ABSTRACT. The application of non-destructive methods of investigation in dams, such as refractive seismic method and Multichannel  Analysis of Surface Waves (MASW) are increasingly effective from the point of choosing the best dam site, as well as in the phases of  construction and maintenance of the structure. The objective of the research was to apply geophysical methods in the structure of the dam  to detect the internal flow of fluids, the presence of voids, find possible fracture zones and variations in the level of saturation of the massif,  characteristics related to permeability and directly linked to the stability of the dam. In this way, geophysical methods have proved to be  excellent tools, because, unlike instrumentation traditionally used in this type of monitoring, such as piezometers and water level indicators,  they can cover a large study area quickly.  This paper aims to present the results of the correlation between the MASW method and the S-wave seismic refraction method in two small earth dams in the countryside of the State of São Paulo, Brazil, more precisely in the  cities of Cordeirópolis and Ipeúna. The main goal was to obtain the depths of the rocky top and the saturated/unsaturated zone of the earth dams using seismic tests under conditions of lack of information about the construction of the dam. The application of geophysical methods  in dams that do not previously have important information (presence of drainage blanket, vertical/horizontal filters, for example) proves to  be a very interesting non-destructive investigation technique.Keywords: geophysics in dams, MASW, seismic refraction, dam investigation. INVESTIGAÇÃO NÃO-DESTRUTIVA EM BARRAGENS DE TERRA DE PEQUENO PORTE USANDO MÉTODOS GEOFÍSICOS: ANÁLISE MULTICANAL DE ONDAS SUPERFICIAIS (MASW) E SÍSMICA DE REFRAÇÃO TOMOGRÁFICARESUMO. A aplicação de métodos não destrutivos de investigação em barragens, como o método da sísmica de refração e a análise  multicanal de ondas de superfície (MASW), são cada vez mais eficazes desde a fase de escolha do melhor local para a instalação da  barragem, bem como nas fases da construção e manutenção da estrutura. O objetivo da pesquisa foi aplicar métodos geofísicos na  estrutura da barragem para detectar o fluxo interno de fluidos, a presença de vazios, encontrar possíveis zonas de fratura e variações no  nível de saturação do maciço, características relacionadas à permeabilidade e diretamente ligadas à estabilidade da barragem. Desta forma, os métodos geofísicos se mostraram como excelentes ferramentas, pois puderam cobrir uma grande área de estudo com rapidez, diferentemente da tradicional instrumentação utilizada neste tipo de monitoramento, como piezômetros e indicadores do nível d'água.  Este trabalho tem como objetivo apresentar os resultados da correlação entre o método  MASW e o método sísmico de refração  com ondas S em duas pequenas barragens de terra no interior do Estado de São Paulo, mais precisamente nas cidades de Cordeirópolis  e Ipeúna. O objetivo principal foi o de obter as profundidades do topo rochoso e da zona saturada/insaturada das barragens de terra  fazendo uso de ensaios sísmicos em condições de ausência de informações a respeito da construção do barramento. A aplicação de  métodos  geofísicos  em  barragens  que  não  possuem  previamente  informações  importantes  (presença  de  tapete  drenante,  filtros  verticais/horizontais, por exemplo) mostra-se como uma técnica de investigação não destrutiva bastante interessante.Palavras-chave: geofísica em barragens, MASW, sísmica de refração, investigação em barragens.

GEOPHYSICAL APPLICATIONS FOR BUKIT BUNUH CRATER EVIDENCES

2016 ◽  
Vol 78 (8-6) ◽  
Author(s):  
Fauzi Andika ◽  
Rosli Saad ◽  
Nordiana Mohd Muztaza ◽  
Nur Azwin Ismail ◽  
Mohd Mokhtar Saidin
Keyword(s):  
Impact Crater ◽  
Agricultural Land ◽  
Seismic Refraction ◽  
Geophysical Methods ◽  
Fractured Bedrock ◽  
Resistivity Imaging ◽  
Magnetic Methods ◽  
Gravity And Magnetic ◽  
Geophysical Surveys

Geophysical surveys were conducted in Bukit Bunuh area, Perak to study an hypothesis of the existence of an impact crater and if so, to identify the perimeter of the crater. Four (4) geophysical methods were applied; seismic refraction, 2-D resistivity imaging, gravity and magnetic methods over approximately 132.25 km2 of developed agricultural land, primary jungle and villages of Bukit Bunuh, Perak and its vicinities. The surveys were conducted from May 2011 until July 2013 and have successfully proven the existence of an impact crater. The crater is about 6 km in diameter with a depth of 5 m – 50 m. There are lots of unusual fractured bedrock which represent features associated with impacted event.

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