Electrical resistivity monitoring of an earthslide with electrodes located outside the unstable zone (Pont‐Bourquin landslide, Swiss Alps)

2021 ◽  
Author(s):  
Grégory Bièvre ◽  
Denis Jongmans ◽  
Thomas Lebourg ◽  
Simon Carrière
Keyword(s):  
Electrical Resistivity ◽  
Swiss Alps ◽  
Unstable Zone

scholarly journals Quasi-3-D resistivity imaging – mapping of heterogeneous frozen ground conditions using electrical resistivity tomography

2009 ◽  
Vol 3 (3) ◽  
pp. 895-918 ◽  
Author(s):  
C. Kneisel ◽  
A. Bast ◽  
D. Schwindt
Keyword(s):  
Electrical Resistivity ◽  
Electrical Resistivity Tomography ◽  
Swiss Alps ◽  
Small Scale ◽  
Frozen Ground ◽  
Resistivity Tomography ◽  
Near Surface ◽  
Glacier Forefield ◽  
Mountain Permafrost ◽  
Ground Conditions

Abstract. Up to now an efficient 3-D geophysical mapping of the subsurface in mountainous environments with rough terrain has not been possible. A merging approach of several closely spaced 2-D electrical resistivity tomography (ERT) surveys to build up a quasi-3-D model of the electrical resistivity is presented herein as a practical compromise for inferring subsurface characteristics and lithology. The ERT measurements were realised in a small glacier forefield in the Swiss Alps with complex terrain exhibiting a small scale spatial variability of surface substrate. To build up the grid for the quasi-3-D measurements the ERT surveys were arranged as parallel profiles and perpendicular tie lines. The measured 2-D datasets were collated into one quasi-3-D file. A forward modelling approach – based on studies at a permafrost site below timberline – was used to optimize the geophysical survey design for the mapping of the mountain permafrost distribution in the investigated glacier forefield. Quasi-3-D geoelectrical imaging is a useful method for mapping of heterogeneous frozen ground conditions and can be considered as a further milestone in the application of near surface geophysics in mountain permafrost environments.

scholarly journals Internal structure of two alpine rockglaciers investigated by quasi-3D electrical resistivity imaging (ERI)

2016 ◽  
Author(s):  
Adrian Emmert ◽  
Christof Kneisel
Keyword(s):  
Electrical Resistivity ◽  
Internal Structure ◽  
Geophysical Methods ◽  
Swiss Alps ◽  
Electrical Resistivity Imaging ◽  
Active Layer Thickness ◽  
Ground Ice ◽  
Resistivity Imaging ◽  
Wide Range ◽  
Ice Content

Abstract. Interactions between different formative processes are reflected in the internal structure of rockglaciers. Its detection can therefore help to enhance our understanding of landform development. For an assessment of subsurface conditions, we present an analysis of the spatial variability of active layer thickness, ground ice content and frost table topography at two different rockglacier sites in the Eastern Swiss Alps by means of quasi-3D electrical resistivity imaging (ERI). This approach enables an extensive mapping of subsurface structures and hence the performance of a spatial overlay between site-specific surface und subsurface characteristics. At Nair rockglacier, we discovered a gradual descent of the frost table in a downslope direction and a homogenous decrease of ice content which follows the observed surface topography. This is attributed to ice formation by refreezing meltwater from an embedded snowbank or from a subsurface ice patch which reshapes the permafrost layer. The heterogeneous ground ice distribution at Uertsch rockglacier indicates that multiple processes on different time domains were involved in rockglacier development. Resistivity values which represent frozen conditions vary within a wide range and indicate a successive formation which includes several rockglacier advances, past glacial overrides and creep processes on the rockglacier surface. In combination with the observed rockglacier topography, quasi-3D ERI enables us to delimit areas of extensive and compressive flow in close proximity. Excellent data quality was provided by a good coupling of electrodes to the ground in the pebbly material of the investigated rockglaciers. Results show the value of the quasi-3D ERI approach but advice the application of complementary geophysical methods for interpreting the results.

scholarly journals Glacier–Permafrost Interaction at a Thrust Moraine Complex in the Glacier Forefield Muragl, Swiss Alps

Geosciences ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 205
Author(s):  
Julius Kunz ◽  
Christof Kneisel
Keyword(s):  
Electrical Resistivity ◽  
Ice Core ◽  
Swiss Alps ◽  
Resistivity Tomography ◽  
Glacier Forefield ◽  
High Electrical Resistivity ◽  
Alpine Glaciers ◽  
Internal Structures ◽  
Ground Penetrating ◽  
Shear Planes

The internal structures of a moraine complex mostly provide information about the manner in which they develop and thus they can transmit details about several processes long after they have taken place. While the occurrence of glacier–permafrost interactions during the formation of large thrust moraine complexes at polar and subpolar glaciers as well as at marginal positions of former ice sheets has been well understood, their role in the formation of moraines on comparatively small alpine glaciers is still very poorly investigated. Therefore, the question arises as to whether evidence of former glacier–permafrost interactions can still be found in glacier forefields of small alpine glaciers and to what extent these differ from the processes in finer materials at larger polar or subpolar glaciers. To investigate this, electrical resistivity tomography (ERT) and ground-penetrating radar (GPR) surveys were carried out in the area of a presumed alpine thrust moraine complex in order to investigate internal moraine structures. The ERT data confirmed the presence of a massive ice core within the central and proximal parts of the moraine complex. Using GPR, linear internal structures were detected, which were interpreted as internal shear planes due to their extent and orientation. These shear planes lead to the assumption that the moraine complex is of glaciotectonic origin. Based on the detected internal structures and the high electrical resistivity values, it must also be assumed that the massive ice core is of sedimentary or polygenetic origin. The combined approach of the two methods enabled the authors of this study to detect different internal structures and to deduce a conceptual model of the thrust moraine formation.

scholarly journals Internal structure of two alpine rock glaciers investigated by quasi-3-D electrical resistivity imaging

2017 ◽  
Vol 11 (2) ◽  
pp. 841-855 ◽  
Author(s):  
Adrian Emmert ◽  
Christof Kneisel
Keyword(s):  
Electrical Resistivity ◽  
Internal Structure ◽  
Swiss Alps ◽  
Electrical Resistivity Imaging ◽  
Rock Glacier ◽  
Ground Ice ◽  
Resistivity Imaging ◽  
Wide Range ◽  
Rock Glaciers ◽  
Ice Content

Abstract. Interactions between different formative processes are reflected in the internal structure of rock glaciers. Therefore, the detection of subsurface conditions can help to enhance our understanding of landform development. For an assessment of subsurface conditions, we present an analysis of the spatial variability of active layer thickness, ground ice content and frost table topography for two different rock glaciers in the Eastern Swiss Alps by means of quasi-3-D electrical resistivity imaging (ERI). This approach enables an extensive mapping of subsurface structures and a spatial overlay between site-specific surface and subsurface characteristics. At Nair rock glacier, we discovered a gradual descent of the frost table in a downslope direction and a constant decrease of ice content which follows the observed surface topography. This is attributed to ice formation by refreezing meltwater from an embedded snow bank or from a subsurface ice patch which reshapes the permafrost layer. The heterogeneous ground ice distribution at Uertsch rock glacier indicates that multiple processes on different time domains were involved in the development. Resistivity values which represent frozen conditions vary within a wide range and indicate a successive formation which includes several advances, past glacial overrides and creep processes on the rock glacier surface. In combination with the observed topography, quasi-3-D ERI enables us to delimit areas of extensive and compressive flow in close proximity. Excellent data quality was provided by a good coupling of electrodes to the ground in the pebbly material of the investigated rock glaciers. Results show the value of the quasi-3-D ERI approach but advise the application of complementary geophysical methods for interpreting the results.

scholarly journals Electrical Resistivity Soundings of Glacier Beds: A Test Study on Grubengletscher, Wallis, Swiss Alps

1984 ◽  
Vol 30 (106) ◽  
pp. 373-376 ◽  
Author(s):  
Wilfried Haeberli ◽  
Werner Fisch
Keyword(s):  
Electrical Resistivity ◽  
Swiss Alps ◽  
Ice Thickness ◽  
Deep Drilling ◽  
Resistivity Sounding ◽  
Alpine Glacier ◽  
Test Study ◽  
Exact Position ◽  
Rock Interface

AbstractElectrical resistivity sounding, using electrodes which are lowered directly to the ice–rock interface in bore holes, is proposed as a technique for studying the exact position of glacier beds, as well as their lithological characteristics. A test study is described on Grubengletscher, a partially cold Alpine glacier in Switzerland. Results of soundings along a 400m long profile indicate that previous depth determinations, based on radio echo-soundings, were in general accurate to within less than 5% of the actual ice thickness. The results also show that the glacier rests on non-consolidated sediments of considerable thickness. The proposed method could add substantial information about glacier sliding and glacier erosion, if applied alongside conventional deep drilling projects.

scholarly journals Electrical Resistivity Soundings of Glacier Beds: A Test Study on Grubengletscher, Wallis, Swiss Alps

1984 ◽  
Vol 30 (106) ◽  
pp. 373-376 ◽  
Author(s):  
Wilfried Haeberli ◽  
Werner Fisch
Keyword(s):  
Electrical Resistivity ◽  
Swiss Alps ◽  
Ice Thickness ◽  
Deep Drilling ◽  
Resistivity Sounding ◽  
Alpine Glacier ◽  
Test Study ◽  
Exact Position ◽  
Rock Interface

AbstractElectrical resistivity sounding, using electrodes which are lowered directly to the ice–rock interface in bore holes, is proposed as a technique for studying the exact position of glacier beds, as well as their lithological characteristics. A test study is described on Grubengletscher, a partially cold Alpine glacier in Switzerland. Results of soundings along a 400m long profile indicate that previous depth determinations, based on radio echo-soundings, were in general accurate to within less than 5% of the actual ice thickness. The results also show that the glacier rests on non-consolidated sediments of considerable thickness. The proposed method could add substantial information about glacier sliding and glacier erosion, if applied alongside conventional deep drilling projects.

Prospecting alpine permafrost with Spectral Induced Polarization in different geomorphological landforms

2020 ◽  
Author(s):  
Theresa Maierhofer ◽  
Timea Katona ◽  
Christin Hilbich ◽  
Christian Hauck ◽  
Adrian Flores-Orozco
Keyword(s):  
Electrical Resistivity ◽  
Thermal State ◽  
Geophysical Methods ◽  
Induced Polarization ◽  
Swiss Alps ◽  
High Mountain ◽  
Monitoring Site ◽  
European Alps ◽  
Mountain Permafrost

<p>Permafrost regions are highly sensitive to climate changes, which has significant implications for the hydrological regimes and the mechanical state of the subsurface leading to natural hazards such as rock slope failures. Therefore, a better understanding of the future evolution and dynamics of mountain permafrost is highly relevant and monitoring of the thermal state of permafrost has become an essential task in the European Alps. Geophysical methods have emerged as well-suited to support borehole data and investigate the spatial distribution and temporal changes of temperature and the degradation of permafrost. In particular, electrical resistivity tomography (ERT) has developed into a routine imaging tool for the quantification of ice-rich permafrost, commonly associated with a significant increase in the electrical resistivity. However, in many cases, the interpretation of the subsurface electrical resistivity is ambiguous and additional information would improve the quantification of the ice content within the subsurface. Theoretical and laboratory studies have suggested that ice exhibits a characteristic induced electrical polarization response. Our results from an extensive field programme including many morphologically different mountain permafrost sites now indicate that this IP response may indeed be detected in the field suggesting the potential of the Induced Polarization (IP) method to overcome such ambiguities. We present here Spectral IP (SIP) mapping results conducted over a broad range of frequencies (0.1-225 Hz) at four representative permafrost sites of the Swiss-, Italian- and Austrian Alps. The mapping results have been used to install long-term permafrost monitoring arrays for a better understanding of subsurface variations associated to climate change. All SIP study sites are located at elevations around 2600 - 3000 m and include comprehensive geophysical and temperature data for validation. We focus on the spatial characterization of each site to address different research questions: to (i) reproduce and improve the mapping of the spatial permafrost extent inferred from previous investigations in the Lapires talus slope,Western Swiss Alps, to (ii) improve the geophysical characterization of the Sonnblick monitoring site located in the Austrian Central Alps, to (iii) determine the transition between permafrost and non-permafrost at the Schilthorn site, Bernese Alps, Switzerland, and to (iv) find the best-suited location for a SIP monitoring profile and conduct year-round measurements at the Cime Bianche site, Western Italian Alps. Our various field applications demonstrate the potential of the IP method for characterizing and monitoring permafrost systems in high-mountain environments.</p>

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