scholarly journals Large-Scale Electrical Resistivity and Bulk Porosity of the Upper Oceanic Crust at Hole 395A

1990 ◽  
Author(s):  
K. Becker
Keyword(s):  
Electrical Resistivity ◽  
Oceanic Crust ◽  
Large Scale ◽  
Bulk Porosity

In situ electrical resistivity and bulk porosity of the oceanic crust Costa Rica Rift

Nature ◽  
1982 ◽  
Vol 300 (5893) ◽  
pp. 594-598 ◽  
Author(s):  
Keir Becker ◽  
R. P. Von Herzen ◽  
T. J. G. Francis ◽  
R. N. Anderson ◽  
J. Honnorez ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Costa Rica ◽  
Oceanic Crust ◽  
Bulk Porosity

Dense 3D electrical resistivity tomography to understand complex deep landslide structures

2021 ◽  
Author(s):  
Julien Gance ◽  
Orlando Leite ◽  
Myriam Lajaunie ◽  
Kusnahadi Susanto ◽  
Catherine Truffert ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Large Scale ◽  
Electrical Resistivity Tomography ◽  
Surface Deformation ◽  
Reference Model ◽  
Slope Instability ◽  
Complex Objects ◽  
Alluvial Deposits ◽  
Resistivity Tomography ◽  
The Village

<p>Large scale slope instabilities are complex objects controlled by multiple parameters. The underground and superficial structure of the slope plays a major role as it often controls water circulations, potentially causing weathering and damaging processes, and permits the local storage of water masses, causing temporary overload. In addition, the structure of the subsurface often delineates rock-volumes with variable mechanical properties, whose spatial distribution greatly influences the behavior of the slope. This work illustrates how Dense 3D Electrical Resistivity Tomography can provide relevant constraints on these parameters.</p><p>The village of Viella, in France (Hautes-Pyrénées), is affected by strong slope movement since 2018, when a massive rockslide above the village modified the stress conditions of the entire slope and, potentially, the hydrogeological context. As a consequence, some houses and infrastructures are progressively damaged, leading to heavy measures (houses evacuation). This complex, deep-seated (> 80 m), slope instability covers an area of ca. 650 000 m², is primarily composed of altered shists, colluviums, and non-consolidated alluvial deposits, forming several kinematic units with surface velocities in the range [0.5 – 5] mm.month<sup>-1</sup>.</p><p> </p><p>A 3D dense electrical resistivity tomography was realized using the FullWaver system, to characterize the structure and the forcing factors of this unstable slope. 55 V-FullWavers receivers (3 -electrodes, 2 channels sensors) were quasi-evenly distributed over a surface area of 400 x 500 m² with an interval of 90 m, apart from the village area, where no electrode could be grounded. Each V-FullWaver recorded signals through two orthogonal dipoles of 25 m length. Current injections were realized with a high-power transmitter (6 kW, 16 A, 3000 V). 235 injection dipoles were used. The system injected current between a fixed remote electrode (more than 1 km away from the site to increase the investigation depth) and a local mobile electrode, moved all over the investigated area in between the V-Fullwaver receivers, with an interval of approximately 40 m, except in the village area.</p><p> </p><p>The resulting 3D resistivity model presents a high spatial variability until 100 to 150 m depth approximately, that highly relates to the complex strain dynamics of the slope and the hydrogeological observations. It highlights the relation between the most active kinematic compartments and the large-scale structure of the slope.</p><p>It provides a first understanding of the role of local compacted rocks in the buildup of surface deformation but also on the localization of heterogeneities (fissures, scarps) which may relate to water circulation paths.</p><p>. This 3D image of the slope is the first structural reference model for future hydrogeological and geomechanical studies aiming at deducing the possible evolution of the slope.</p>

Conceptualizing Groundwater-Surface Water Interactions within the Ogallala Aquifer Region using Electrical Resistivity Imaging

2019 ◽  
Vol 24 (2) ◽  
pp. 185-199
Author(s):  
Weston J. Koehn ◽  
Stacey E. Tucker-Kulesza ◽  
David R. Steward
Keyword(s):  
Electrical Resistivity ◽  
Surface Water ◽  
Large Scale ◽  
Water Movement ◽  
Alluvial Aquifer ◽  
Electrical Resistivity Imaging ◽  
Ogallala Aquifer ◽  
Aquifer Recharge ◽  
Arkansas River ◽  
Resistivity Imaging

Dynamic interactions between rivers and aquifers are controlled by the underlying hydrogeologic environment, as well as the type of hydrologic connection between the riverbed and saturated zone. The Arkansas River supplies groundwater to a heavily exploited region of the Ogallala Aquifer across Western Kansas. Site characterizations of this region using existing well and borehole data reveal large scale geologic features that significantly impact recharge processes, such as the Bear Creek fault. However, the existing hydrogeologic data do not provide the level of detail needed to fully understand the contribution of the losing river system to Arkansas Alluvial aquifer recharge. Knowledge about riverbed hydrogeology is acquirable using electrical resistivity imaging (ERI) surveys. ERI surveys and soil sample analysis were conducted at three sites along the Arkansas River to characterize the hydrogeologic environment within the Arkansas River Alluvial aquifer, which overlies the Ogallala aquifer. Temporal changes in electrical resistivity served as an indicator of the hydrologic response of the alluvial sediments to changes in river discharge as different patterns of water movement from the Arkansas River to Arkansas River Alluvial aquifer were observed. The ERI surveys revealed both fully connected and disconnected regions between the riverbed and groundwater table. The results supplement the existing geologic characterization of this region, and provide a more spatially detailed view of the hydrogeologic environment that has a direct causative effect on groundwater surface water interactions. Understanding the behavior of river-aquifer interactions is vital to the ability to predict the future holds of this important groundwater system.

scholarly journals Large-scale electrical resistivity tomography in the Cheb Basin (Eger Rift) at an International Continental Drilling Program (ICDP) monitoring site to image fluid-related structures

Solid Earth ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 1951-1969 ◽  
Author(s):  
Tobias Nickschick ◽  
Christina Flechsig ◽  
Jan Mrlina ◽  
Frank Oppermann ◽  
Felix Löbig ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Fault Zone ◽  
Large Scale ◽  
Monitoring Site ◽  
Earthquake Activity ◽  
Resistivity Tomography ◽  
Scientific Drilling ◽  
Eger Rift ◽  
Geophysical Surveys ◽  
Cheb Basin

Abstract. The Cheb Basin, a region of ongoing swarm earthquake activity in the western Czech Republic, is characterized by intense carbon dioxide degassing along two known fault zones – the N–S-striking Počatky–Plesná fault zone (PPZ) and the NW–SE-striking Mariánské Lázně fault zone (MLF). The fluid pathways for the ascending CO2 of mantle origin are one of the subjects of the International Continental Scientific Drilling Program (ICDP) project “Drilling the Eger Rift” in which several geophysical surveys are currently being carried out in this area to image the topmost hundreds of meters to assess the structural situation, as existing boreholes are not sufficiently deep to characterize it. As electrical resistivity is a sensitive parameter to the presence of conductive rock fractions as liquid fluids, clay minerals, and also metallic components, a large-scale dipole–dipole experiment using a special type of electric resistivity tomography (ERT) was carried out in June 2017 in order to image fluid-relevant structures. We used permanently placed data loggers for voltage measurements in conjunction with moving high-power current sources to generate sufficiently strong signals that could be detected all along the 6.5 km long profile with 100 and 150 m dipole spacings. After extensive processing of time series for voltage and current using a selective stacking approach, the pseudo-section is inverted, which results in a resistivity model that allows for reliable interpretations depths of up than 1000 m. The subsurface resistivity image reveals the deposition and transition of the overlying Neogene Vildštejn and Cypris formations, but it also shows a very conductive basement of phyllites and granites that can be attributed to high salinity or rock alteration by these fluids in the tectonically stressed basement. Distinct, narrow pathways for CO2 ascent are not observed with this kind of setup, which hints at wide degassing structures over several kilometers within the crust instead. We also observed gravity and GPS data along this profile in order to constrain ERT results. A gravity anomaly of ca. −9 mGal marks the deepest part of the Cheb Basin where the ERT profile indicates a large accumulation of conductive rocks, indicating a very deep weathering or alteration of the phyllitic basement due to the ascent of magmatic fluids such as CO2. We propose a conceptual model in which certain lithologic layers act as caps for the ascending fluids based on stratigraphic records and our results from this experiment, providing a basis for future drillings in the area aimed at studying and monitoring fluids.

scholarly journals Characterizing large-scale glaciotectonic sediment deformation using electrical resistivity methods

2016 ◽  
Vol 13 (2) ◽  
pp. S39-S49 ◽  
Author(s):  
R L Aylsworth ◽  
R L Van Dam ◽  
G J Larson ◽  
M A Jessee
Keyword(s):  
Electrical Resistivity ◽  
Large Scale ◽  
Sediment Deformation

The formation of new oceanic crust

1965 ◽  
Vol 258 (1088) ◽  
pp. 123-136 ◽  
Keyword(s):  
Oceanic Crust ◽  
Red Sea ◽  
Gulf Of California ◽  
Large Scale ◽  
Continental Drift ◽  
Active Regions ◽  
Seismic Exploration ◽  
Seismic Velocities ◽  
Crustal Structures ◽  
Rift Zones

Seismic exploration at sea has established that the oceanic crust is completely different from that of the continents. If we accept continental drift, it is therefore necessary to invoke a mechanism for the evolution of new oceanic crust. An attempt is made to locate regions where new oceanic crust may be forming and it is suggested that these regions are related to regions of uprising convection in the mantle. The crustal structures beneath the Red Sea and the Gulf of California are very similar and closer to oceanic than continental. As these are seismically active regions of extension, it seems reasonable to suppose that they represent areas where new oceanic crust is evolving in regions of continental break-up. These rift zones are in continuity with the seismically active oceanic rifts where similar seismic velocities (about 7 km/s) have been found and it is inferred that the oceanic rifts also represent regions where new oceanic crust is evolving. These are generally near the centres of the oceans. The tensional rift zones which are regions of shallow seismicity help to locate regions of rising convection currents in the mantle. It is further suggested that regions of deep and intermediate focus earthquakes locate regions of descending convection currents and maps of earthquake distributions are used to reveal a possible large-scale pattern of mantle convection. It is supposed that new oceanic crust evolves over the rising convection currents. A study is therefore made of the crustal sections for the Red Sea, Gulf of California and mid-oceanic rift regions and these are compared with typical continental and oceanic crusts. A possible mechanism for the evolution of new oceanic crust is given based on the isostatic equilibrium of oceans and continents.

Formation of Aluminum Films Using a High Rate ICB Source

1991 ◽  
Vol 235 ◽  
Author(s):  
H. Tsukazaki ◽  
G. Okamoto ◽  
Y. Hashimoto ◽  
K. Yamanishi ◽  
M. Tanaka ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Integrated Circuit ◽  
Large Scale ◽  
High Rate ◽  
Cluster Beam ◽  
Aluminum Films ◽  
Cluster Beams ◽  
Deposited Films ◽  
Coverage Profile ◽  
Excellent Coverage

ABSTRACTAn ionized cluster beam (ICB) source has been developed for high rate deposition, and its possible application to ultra large scale integrated circuit (ULSI) metallization was investigated. Aluminum films were deposited onto oxidized silicon wafers using the ICB source. It was shown that an electrical resistivity was almost the same as the value for bulk aluminum, and the surface morphology of deposited films was improved by controlling the ionization and acceleration conditions of the cluster beam. It was confirmed that the ICB method showed an excellent coverage profile in contact holes when compared with the conventional sputtering method. Using the directivity of cluster beams, contact holes of 1.5 in aspect ratio were successfully metallized. From these results, it became evident that the ICB source is a favorable method for ULSI metallization.

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