Performance of geophysical methods in determining fault zone at Darakeh Area (Tehran Province; Iran)

2022 ◽  
pp. 104534
Author(s):  
Mohsen Jahanbin ◽  
Seyed Reza Mehrnia ◽  
Hamidreza Shirvani-Mahdavi ◽  
Habib Rahimi
Keyword(s):  
Fault Zone ◽  
Geophysical Methods ◽  
Tehran Province

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.

scholarly journals Characteristics of clay minerals in gouges of the Red River fault, Vietnam

2014 ◽  
Vol 17 (3) ◽  
pp. 27-33
Author(s):  
Bac Hoang Bui ◽  
Hung The Khuong ◽  
Thanh Xuan Ngo ◽  
Dung Tien Nguyen
Keyword(s):  
Clay Minerals ◽  
Fault Zone ◽  
High Speed ◽  
Active Fault ◽  
Geophysical Methods ◽  
Red River ◽  
General View ◽  
Earthquake Activity ◽  
X Ray ◽  
Red River Fault

Earthquake is currently one of the biggest concerns in Vietnam, especially, when a number of earthquakes recorded by seismometers in recent years imply the danger of earthquake in the country. In Vietnam, the recorded earthquakes were pinpointed as the consequence of stratigraphic movements along active fault zones. Identifying of the activities of fault is mainly based on tectonics, geomorphology and observation techniques utilizing geophysical methods with data on seismic waves of earthquakes. However, determining the active fault intervals is generally a difficult task which is of the interest of many domestic and worldwide scientists. One of the methods of identifying the active intervals of faults that has been applied in many countries is studying authigenetic clay mineral forming in fault planes and cataclasites due to fault activities. The movement of fault surface will create fault gouges formed at low temperature, the typical of which is illite mineral. In order to date active phases of faults, K-Ar dating of illite mineral is now proved to be an effective method. Based on the successful studies on modern fault activities using the method of K-Ar dating of authigeneticillite, and with the goal of having a general view on the activities of Red Rive Fault, Vietnam and more information on earthquakes caused by this fault, the authors have conducted a study on characteristics of the authigenetic clay minerals formed by fault activities, accordingly identifying their formation periods using K-Ar dating method. Based on the recorded ages, we hope to be able to explain the active fault intervals and its relationship with earthquake activity in the surround areas. In this paper, we are presenting the initial results about characteristics of clay minerals in gouges of the Red River fault zone, Vietnam. Several gouges amples were collected from the Red River fault zone. Then, they were separated into four grain-size fractions (<0.1, 0.1 - 0.4, 0.4 - 1.0, and 1-2µm) using standard gravitational settling and high-speed centrifuging techniques based on a preliminary analysis. The samples after separating were characterized by using FTIR spectroscopy, X-ray diffraction (XRD), Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX). The results indicated that authigenetic clay minerals forming in fault planes due to fault activities such as illite, illite/smectite is in samples with significant amounts. These are important results in defining modern active time of Red River fault zone using method of K-Ar dating for authigenetic clay minerals.

scholarly journals Multi-disciplinary characterizations of the Bedretto Lab – a unique underground geoscience research facility

2021 ◽  
Author(s):  
Xiaodong Ma ◽  
Marian Hertrich ◽  
Florian Amann ◽  
Kai Bröker ◽  
Nima Gholizadeh Doonechaly ◽  
...  
Keyword(s):  
Fault Zone ◽  
Mechanical Response ◽  
Geophysical Methods ◽  
General Setting ◽  
Current Status ◽  
Rock Masses ◽  
Test Bed ◽  
In Situ Conditions ◽  
In Situ Experiments

Abstract. The increased interest in subsurface development (e.g., unconventional hydrocarbon, deep geothermal, waste disposal) and the associated (triggered or induced) seismicity calls for a better understanding of the hydro-seismo-mechanical coupling in fractured rock masses. Being able to bridge the knowledge gap between laboratory and reservoir scales, controllable meso-scale in situ experiments are deemed indispensable. In an effort to access and instrument rock masses of hectometer size, the Bedretto Underground Laboratory for Geosciences and Geoenergies (‘Bedretto Lab’) was established in 2018 in the existing Bedretto Tunnel (Ticino, Switzerland), with an average overburden of 1000 m. In this paper, we introduce the Bedretto Lab, its general setting and current status. Combined geological, geomechanical and geophysical methods were employed in a hectometer-scale rock mass explored by several boreholes to characterize the in situ conditions and internal structures of the rock volume. The rock volume features three distinct units, with the middle fault zone sandwiched by two relatively intact units. The middle fault zone unit appears to be a representative feature of the site, as similar structures repeat every several hundreds of meters along the tunnel. The lithological variations across the characterization boreholes manifest the complexity and heterogeneity of the rock volume, and are accompanied by compartmentalized hydrostructures and significant stress rotations. With this complexity, the characterized rock volume is considered characteristic of the heterogeneity that is typically encountered in subsurface exploration and development. The Bedretto Lab can adequately serve as a test-bed that allows for in-depth study of the hydro-seismo-mechanical response of fractured crystalline rock masses.

High-resolution quantitative seismic imaging of a strike-slip fault with small vertical offset in clay rocks from underground galleries: Experimental platform of Tournemire, France

Geophysics ◽  
2014 ◽  
Vol 79 (1) ◽  
pp. B1-B18 ◽  
Author(s):  
François Bretaudeau ◽  
Céline Gélis ◽  
Donatienne Leparoux ◽  
Romain Brossier ◽  
Justo Cabrera ◽  
...  
Keyword(s):  
High Resolution ◽  
Fault Zone ◽  
Waveform Inversion ◽  
Geophysical Methods ◽  
Fault System ◽  
Seismic Velocities ◽  
Clay Rock ◽  
Secondary System ◽  
Experimental Platform ◽  
Early Arrival

Imaging tectonic faults with small vertical offsets in argillites (clay rock) using geophysical methods is challenging. In the context of deep radioactive waste disposals, the presence of such faults has to be assessed because they can modify the rock-confining properties. In the Tournemire Experimental Platform (TEP, Aveyron, France), fault zones with small vertical offsets and complex shape have been identified from underground works. However, 3D high-resolution surface seismic methods have limitations in this context that led us to consider the detection and characterization of the faults directly from underground works. We investigated the potential of seismic full-waveform inversion (FWI) applied in a transmission configuration to image the clay rock medium in a horizontal plane between galleries and compared it with first-arrival traveltime tomography (FATT). Our objective was to characterize seismic velocities of a block of argillites crossed by a subvertical fault zone with a small vertical offset. The specific measurement configuration allowed us to neglect the influence of the galleries on the wave propagation and to simplify the problem by considering a 2D isotropic horizontal imaging domain. Our FWI scheme relied on a robust adaptation of early arrival waveform tomography. The results obtained with FATT and FWI were in accordance, and both correlated with the geologic observations from the gallery walls and boreholes. We found that even though various simplifications was done in the inversion scheme and only a part of the data was used, FWI allowed us to get higher resolution images than FATT, and it was especially less sensitive to the incomplete illumination because it also used diffracted energy. Our results highlighted the complexity of the fault zone, showing a complex interaction of the main fault system with a secondary system composed of decimetric fractures associated with the presence of water.

The structure of the Vladikavkaz Fault Zone based on the study utilizing a complex of geological-geophysical methods

2011 ◽  
Vol 47 (4) ◽  
pp. 307-313 ◽  
Author(s):  
A. V. Gorbatikov ◽  
A. N. Ovsyuchenko ◽  
E. A. Rogozhin ◽  
M. Yu. Stepanova ◽  
N. V. Larin
Keyword(s):  
Fault Zone ◽  
Geophysical Methods

scholarly journals The resistivity image of the Muráň fault zone (Central Western Carpathians) obtained by electrical resistivity tomography

2012 ◽  
Vol 63 (3) ◽  
pp. 233-239 ◽  
Author(s):  
René Putiška ◽  
Ivan Dostál ◽  
Andrej Mojzeš ◽  
Vojtech Gajdoš ◽  
Kamil Rozimant ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Fault Zone ◽  
Electrical Resistivity Tomography ◽  
Geophysical Methods ◽  
Western Carpathians ◽  
Small Scale ◽  
Second Phase ◽  
Resistivity Tomography ◽  
Central Western Carpathians ◽  
Resistivity Image

The resistivity image of the Muráň fault zone (Central Western Carpathians) obtained by electrical resistivity tomographyThe paper describes the application of geophysical prospecting techniques for estimation of the fault's inclination. The field survey was carried out across the Muráň fault structure in the Slovenské rudohorie Mts (central Slovakia). Three different geophysical methods were used to map the fault zone: Electrical Resistivity Tomography (ERT), induced polarization (IP) and radon emanometry. All these methods have been used to locate the fault zone area, but the principal aims of this research are to test the efficiency of the 2D ERT technique to recognize the geometrical characterization of the fault and to improve our tectonic knowledge of the investigated area. For the synthetic cases, three geometric contexts were modelled at 60, 90 and 120 degrees and computed with the l2norm inversion method, the l1norm with standard horizontal and vertical roughness filter and the l1norm with diagonal roughness filter. In the second phase this geophysical methodology was applied to fieldwork data. Our results confirm that the ERT technique is a valuable tool to image the fault zone and to characterize the general geometry, but also the importance of setting up the right inversion parameters. The main contribution of the geophysical investigations in this case was the determination of the location and confirmation of the inclination of the Muráň fault. The result of this study is the ability to make a visual estimation of the direction and dip of the fault. Pursuant to this work the dipole-dipole electrode configuration produces the best resolution, particularly for the location of vertical and dipping structures. The advantage of this array is that it shows the ability to assess the trend of the dip and therefore it can be strongly recommended. The result is also a case study of a small scale tectonic survey involving geophysical methods.

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.

Shear strength behavior of Mont Terri Opalinus Claystone in fault zone

2015 ◽  
Vol 10 (1) ◽  
pp. 31-38
Author(s):  
Ildikó Buocz ◽  
Nikoletta Rozgonyi-Boissinot ◽  
Ákos Török
Keyword(s):  
Shear Strength ◽  
Fault Zone ◽  
Strength Behavior ◽  
Mont Terri
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