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.

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.

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.

Integration of multi-parameter geophysical data to the structural mapping of a landslide’s subsurface

2021 ◽  
Author(s):  
Vincenzo Critelli ◽  
Francesco Ronchetti ◽  
Alessandro Corsini ◽  
Matteo Berti ◽  
Gianluigi Di Paola
Keyword(s):  
Seismic Reflection ◽  
Mass Movement ◽  
Geophysical Methods ◽  
Three Dimensional ◽  
Swiss Alps ◽  
P Wave ◽  
Seismic Reflection Profile ◽  
Basal Surface ◽  
Refraction Tomography ◽  
Geophysical Surveys

<p>With this note, we show a three-dimensional reconstruction of the basal surface of a large-scale and deep-seated rock-slide located in Northern Apennines (Northern Italy), obtained by integrating direct observations from boreholes and data from multi-methods geophysics. This type of landslides is so intrinsically complex and extended, that borehole investigations alone are generally insufficient to fully characterize the inner structures. To overcame such limitations, geophysical surveys are employed extensively (Bogoslovsky and Ogilvy 1977; Bruno and Marillier 2000; Bichler et al. 2004; Jongmans and Garambois 2007). In this study, we integrated multi-parameter data derived from 400 m of DC electrical resistivity tomography (ERT), 466 m of P-wave seismic refraction tomography (SRT), 420 meters of P-wave seismic reflection profile (SRF) together with 156 HVSR seismic noise recordings processed with spectral ratio methodology (Nakamura 1989). To constrain the inversion of the HVSR and migrate to the spatial domain the SRF, the P-wave velocity domains from SRT profiles were used after comparison with stratigraphic data. Moreover, the ERT profile fitted the geometrical features depicted by SRF profile. By means of all these data, we managed to map the surface exhibiting the highest acoustic impedance and the most relevant spatial continuity, which, according to the stratigraphic data, is to be ascribed to the basal interface between the fractured flysch rock masses involved in deep-seated sliding and the underlying undamaged bedrock. Comparison with inclinometer data also showed, presently, the active sliding surfaces match the mapped interface only in some locations, whereas in other they are shallower.  This indicates that the mapped basal surface can be considered the envelope of the maximum volume involved, in the past, by the mass movement, and that part of such volume is nowadays no longer moving. The integration of multi-geophysical surveys, in this case, proved to be a valuable way to spatialize evidences collected by boreholes, providing the basis for a three-dimensional geological model of the slope that can later on be used for modelling purposes.</p><p><strong>References</strong></p><p>Bichler, A., P. Bobrowsky, M. Best, M. Douma, J. Hunter, T. Calvert, and R. Burns. 2004. “Three-Dimensional Mapping of a Landslide Using a Multi-Geophysical Approach: The Quesnel Forks Landslide.” Landslides 1 (1): 29–40. https://doi.org/10.1007/s10346-003-0008-7.</p><p>Bogoslovsky, V A, and A A Ogilvy. 1977. “GEOPHYSICAL METHODS FOR THE INVESTIGATION OF LANDSLIDES.” GEOPHYSICS 42 (3): 562–71. https://doi.org/10.1190/1.1440727.</p><p>Bruno, F., and F. Marillier. 2000. “Test of High-Resolution Seismic Reflection and Other Geophysical Techniques on the Boup Lanslide in the Swiss Alps.” Surveys in Geophysics 21 (4): 333–48.</p><p>Jongmans, Denis, and Stéphane Garambois. 2007. “Geophysical Investigation of Landslides: A Review.” Bulletin de La Societe Geologique de France 178 (2): 101–12. https://doi.org/10.2113/gssgfbull.178.2.101.</p><p>Nakamura, Y. 1989. “Method for Dynamic Characteristics of Subsurface Using Microtremor on the Ground Surface.” Proc. 20th JSCE Earthquake Eng. Symposium.</p>

scholarly journals Landslide Investigation Using Seismic Refraction Tomography Method: A Review

2021 ◽  
Vol 64 (Vol. 64 (2021)) ◽  
Author(s):  
Parisa Imani ◽  
Amr Abd El-Raouf ◽  
Gang Tian
Keyword(s):  
Water Saturation ◽  
Mass Movement ◽  
Seismic Refraction ◽  
Cost Effective ◽  
Time Lapse ◽  
Near Surface ◽  
Advantages And Disadvantages ◽  
Refraction Tomography ◽  
Landslide Mass ◽  
Novel Algorithms

Since the early 1960s, near-surface seismic refraction tomography (SRT) has been extensively used as a non-invasive and cost-effective geophysical method to characterize complex geological structures for landslide investigation. This geophysical technique is able to characterize the slope material, the sliding surface's geometry, the landslide mass movement, the physical properties of media, and the water saturation effects on the slope. Therefore, this method has become an appropriate method due to the increasing progress of novel algorithms and the improvements of field-data collection systems. In this paper, we attempt to review the essential research that investigated various types of landslides influenced by water saturation and landslide materials and identified in various areas, since the year 2000. Significant conclusions obtained by applying different survey strategies and data processing algorithms in seismic refraction surveys are widely discussed concentrating on the advantages and disadvantages of this method. The main results obtained by the few available studies applying time-lapse SRT (TLSRT) are particularly analyzed.

scholarly journals PRELIMINARY GULLY HAZARD ASSESSMENT USING 2D-ERT AND 2D-SRT GEOPHYSICAL SURVEYS: A CASE STUDY IN SOUTHEASTERN NIGERIA

2021 ◽  
pp. 49-65
Author(s):  
GN Egwuonwu ◽  
EI Okoyeh ◽  
DC Agarana ◽  
EG Nwaka ◽  
OB Nwosu ◽  
...  
Keyword(s):  
Seismic Refraction ◽  
P Wave ◽  
Lateritic Soil ◽  
Risk Level ◽  
Clayey Sand ◽  
Southeastern Nigeria ◽  
Velocity Models ◽  
Refraction Tomography ◽  
Geophysical Surveys ◽  
Oriented Parallel

Two-dimensional Electrical Resistivity Tomography (2DERT) and Seismic Refraction Tomography (2DSRT) were concurrently applied in assessment of a gully site with the view of assessing its stability and risk level. Eight profile lines oriented parallel and perpendicular to the boundary of the gully were surveyed. As a result, apparent resistivity model tomograms in the range of 1-9,000 and p-wave velocity models in the range of 300-700 were obtained from the two techniques respectively. Interpretation of the models obtained show predominance of unconsolidated clay, shale intercalates, clayey sand, sandy clay and weathered lateritic soil at shallow depths. Low amplitude undulating refracting layers, landslide slip subsurface and lose horizons were also delineated at shallow depths. The predominance of weak, clayey and unconsolidated lithology at the gully site suggests evidence of unstable gravitational equilibrium which imply environmental hazard. The plausible deductions made from the two

scholarly journals Chasing a hidden fracture using seismic refraction tomography: case study Preonzo, Switzerland

2020 ◽  
Author(s):  
Mauro Häusler ◽  
Franziska Glüer ◽  
Jan Burjánek ◽  
Donat Fäh
Keyword(s):  
Rock Mass ◽  
Seismic Refraction ◽  
Slope Instability ◽  
Mode Analysis ◽  
Mode Shapes ◽  
Small Aperture ◽  
Higher Modes ◽  
Refraction Tomography ◽  
Tension Cracks ◽  
Unstable Rock

<p>The Preonzo rock slope instability in southern Switzerland partly collapsed in 2012, releasing a volume of ~210’000 m3 and leaving behind an unstable rock mass of about 140’000 m3. Shortly after the collapse, a small-aperture seismic array measurement was performed on the remaining unstable volume. The analysis of these data showed a fundamental resonance frequency of about 3.5 Hz and strong wavefield amplifications with factors of more than 30 in direction perpendicular to open tension cracks. Normal mode analysis by frequency domain decomposition using the fundamental and several higher modes allowed for mapping the fracture network of the instability.<br>However, the observed amplification factors and mode shapes could not be explained solely by the open tension cracks visible at the surface. Strong amplifications, especially at frequencies of higher modes, were observed on the uphill part of the rear fracture, which was supposed to be outside the presumed unstable area. The zone where amplifications rapidly decreased in the uphill direction coincides roughly with a geomorphological lineament in the field, interpreted as an additional, but hidden, rear fracture. <br>We performed active seismic refraction tomography across this lineament and discovered distinct low velocity anomalies in the transition zone from high to low amplifications, supporting the interpretation of an additional fracture. Considering this new finding, the volume of the unstable rock mass increases by about 40 %. </p>

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.

Pipeline Route Assessment at River Crossings and in Steep Terrain: Geophysical, Hydrologic and Geotechnical Characterization

2002 ◽  
Author(s):  
Gilein J. Steensma ◽  
Mark A. Kappelhoff ◽  
Duncan A. McInnis ◽  
Eric Gilson
Keyword(s):  
Seismic Refraction ◽  
Geophysical Data ◽  
River Channels ◽  
Refraction Tomography ◽  
Geological Conditions ◽  
Geophysical Surveys ◽  
The Face ◽  
Steep Terrain ◽  
Difficult Terrain ◽  
Lateral Variations

Pipeline river crossings and sections of pipeline routes where steep terrain requires directionally drilled borings have the highest chance of being successfully designed and constructed if subsurface geological conditions are understood. In this paper we present results of geophysical surveys conducted to characterize the subsurface at two pipeline river crossings and at a site where steep topography would likely require directional boring below the face of a steep hillside. The objective is to help assess and minimize the risk in engineering design in difficult terrain by analyzing subsurface geology from geophysical data and vertical geotechnical borings, and evaluating the dynamic behavior of the river itself through hydrologic analysis. Risk factors can be assigned on the basis of lithology and environmental considerations relating to the level of potential impact in different parts of the crossing. The laterally heterogeneous nature of river channels, consisting of stacked paleochannels and floodplains could require a significant number of vertical geotechnical borings for adequate characterization of the entire crossing. We find that a combination of electrical resistivity tomography (ERT), seismic refraction tomography (SRT) and ground penetrating radar (GPR) data can efficiently provide us with an understanding of electrical and mechanical properties from which lateral variations and depth extent of lithology along the proposed boring can be inferred. Confirmatory vertical geotechnical borings allow us to verify our interpretation at two locations. Geophysical data are used to laterally extrapolate the lithologic interpretation and define, in conjunction with surface water hydrologic considerations, the minimum depth of directionally drilled borings and optimum locations of ingress/egress points. The investment in a geological assessment study to understand subsurface conditions prior to beginning horizontal boring operations is essential to mitigate risk and ultimately may save money. In the case of steep terrain, geophysical data can provide valuable information on the vertical and lateral variations in subsurface properties in areas where it would be impossible to safely drill vertical borings. Our last case history is an example of the geological information that can be efficiently inferred from geophysical surveys conducted in steep terrain.

Geophysical characterization of inactive/active rock glaciers in the semi-arid Andes using seismic, geoelectrics and GPR

2020 ◽  
Author(s):  
remi valois ◽  
Nicole Schafer ◽  
Giulia De Pasquale ◽  
Gonzalo Navarro ◽  
Shelley MacDonell
Keyword(s):  
Electrical Resistivity ◽  
Seismic Velocity ◽  
Seismic Refraction ◽  
Geophysical Methods ◽  
Late Summer ◽  
Relevant Information ◽  
Refraction Tomography ◽  
Rock Glaciers ◽  
Ice Content ◽  
Ground Penetrating

<p>Rock glaciers play an important hydrological role in the semiarid Andes (SA; 27º-35ºS). They cover about three times the area of uncovered glaciers and they are an important contribution to streamflow when water is needed most, especially during dry years and in the late summer months. Their characteristics such as their extension in depth and their ice content is poorly known. Here, we present a case study of one active rock glacier and periglacial inactive geoform in Estero Derecho (~30˚S), in the upper Elqui River catchment, Chile. Three geophysical methods (ground-penetrating radar and electrical resistivity and seismic refraction tomography) were combined to detect the presence of ice and understand the internal structure of the landform. The results suggest that the combination of electrical resistivity and seismic velocity provide relevant information on ice presence and their geometry. Radargrams shows diffraction linked to boulders presence but some information regarding electromagnetic velocity could be extracted. These results strongly suggest that such landforms contain ice, are therefore important to include in future inventories and should be considered when evaluating the hydrological importance of a particular region.</p><p> </p>

GEOPHYSICAL ACTIVITY IN 1975

Geophysics ◽  
1976 ◽  
Vol 41 (4) ◽  
pp. 780-794 ◽  
Author(s):  
H. R. Espey
Keyword(s):  
Geophysical Methods ◽  
Groundwater Exploration ◽  
Computer Processing ◽  
Petroleum Exploration ◽  
Government Agencies ◽  
Survey Questionnaire ◽  
Geothermal Exploration ◽  
Unit Costs ◽  
Geophysical Surveys ◽  
Geophysical Techniques

This report provides statistics on worldwide use of geophysical methods in 1975. Data were obtained primarily through a survey questionnaire which was mailed out to more than 1500 companies, government agencies, and universities that use geophysical techniques for petroleum exploration, oceanography, engineering, mining, geothermal exploration, and groundwater exploration. Response to the survey was excellent and provided detailed information on more than 2100 geophysical surveys. Data on unit costs, methods used, and line‐miles covered are believed to be more accurate this year as a result of better cooperation from industry in filling out the questionnaires. Computer processing was utilized in tabulating the statistics to provide increased accuracy and detail. Data not supplied on the questionnaire for costs or line mileage were estimated on the basis of worldwide averages to produce a more comprehensive report.

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