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Cross section through Landform complex 2 showing subsurface topography estimated from different methods.
Source publication
Three geophysical methods, ground penetrating radar, 2D-resistivity and seismic refraction were applied to two landform complexes in a high-alpine valley in Switzerland to investigate their internal structure. Results of the different methods were analysed separately, before conclusions about sediment thickness and geomorphologic implications were...
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Techniques for mapping the distribution of buried glacier ice are discussed and the results, from a study carried out within the framework of flood protection work in the Italian Alps, are presented. Bottom temperatures of the winter snow cover (BTS) primarily indicate the heat flow conditions in the underlying ground and mainly depend on the prese...
Geomorphological, geological and geophysical investigations were carried out to estimate the amount of sediments
stored in the Peynin catchment of about 15 km², situated on the Queyras valley, on the Southern French Alps.
Sediment storages were identiied, characterized and mapped on GIS from extensive ieldwork. Based on these
data, two models of se...
Climate effects relating to air temperature, radiation, snow cover, and rainfall combine with thaw and infiltration processes to cause changes in the thermal response and associated creep deformations in rock glaciers, which are the geomorphological expression of Alpine permafrost. The annual surface creep of some rock glaciers has accelerated rece...
We 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 ∼1...
Citations
... Geophysical methods, which allow rapid exploration of large areas without changing their natural conditions at each site in depth and spatial dimensions, allow the non-invasive determination of physical properties and mechanical behaviour of the soils and rocks such as softness-stiffness characterization of the geological units, soil classification, possible structural elements (faults, fractures, voids, caves, cracks, etc.), geometry of the soil (soil thickness and depth to the bedrock), dynamic-elastic parameters and groundwater content. Accordingly, geophysical engineering studies have recently become an important area of use in the waste management workflow, and the use of geophysical methods has become widespread (Otto and Sass 2006;Schrott and Sass 2008;Kowalczyk et al. 2017). In this context, magnetic, electrical resistivity, electromagnetic, natural potential, ground radar penetrating and seismic (refraction, reflection and surface wave analysis) methods are frequently applied. ...
This study aimed to assess the suitability of the potential solid waste landfill sites in seven provinces (Samsun, Ordu, Giresun, Trabzon, Gümüşhane, Bayburt and Artvin) in the Eastern Blacksea Region of Türkiye. The earthquake hazard analysis for two major earthquakes which occurred in the region was first carried out. Then, the geophysical methods including seismic refraction tomography (SRT), electrical resistivity tomography (ERT) and Multichannel Analysis of Surface Waves (MASW) were conducted to find out the structural and physical properties of the subsurface which include the layering, soil classification based on VS30 and the groundwater content at 25 locations of 13 in target provinces. The integrated interpretation of whole data sets demonstrates that Işıktepe, Esence, Çamburnu and Kazantaş which are characterized by VP > 1200 m/s, VS30 ≥ 400 m/s, ρ > 70 Ohm-m, low earthquake hazard and seismicity are more suitable among others. Vezirköprü, Şebinkarahisar, Yenice, Bayburt-Center, Balkaynak and Murgul will be suitable after a geotechnical reclamation due to moderate seismic velocities and electrical resistivity which are 900 < VP ≤ 1200 m/s, 200 < VS30 < 400 m/s and 10 < ρ ≤ 70 Ohm-m representing stiff and wet soils. In addition, Bafra, Ağalık and Ovacık were considered to be unsuitable due to the presence of thick, water-saturated soft soil and extremely weathered rocks. Finally, this study shows that the joint interpretation of seismicity and geophysical data in potential waste landfill sites, extremely important for the planning and development of a city, can provide the valuable information which will enable to prevent possible deformations, environmental problems and economic losses after waste landfill.
... 94 He hypothesized that during the cold season cold air enters talus through holes in the snow cover, moves downward, pushes the warm air upward, and eventually escapes through holes from the upper part of the talus. Sawada et al. 95 and Delaloye and Lambiel 84 proposed an alternative explanation in which F I G U R E 4 Ground-penetrating radar (GPR) measurements of a talus-moraine complex in the Swiss Alps (reprinted from Otto and Sass 18 with copyright permission from Elsevier). ...
Talus, as the product of movement and accumulation along the slope after the cracking of cliffs or steep rock walls, is a common landform in the mountain periglacial environment. Significant thermal anomalies within talus have been widely reported to be a result of cooling effects. During the cold season, the increased temperature difference between talus and the ambient environment strengthens the intensity of convection (vertical flows) and transforms into upward advection (lateral flows) and exhausts the internal warm current. During the warm season, heat is concentrated on the surface of the talus, and the internal dominant cold current moves downward along the slope by advection. The principle of the proactive cooling effects of talus has been widely utilized in railway construction within permafrost regions as embankments to alleviate degradation of the underlying permafrost. However, limited model studies have examined the cooling effects of blocky debris in nature, and in situ observations are rare. Therefore, it will be important to increase observations and develop process‐based models that couple heat conduction, convection/advection, water transfer processes, and even the latent heat of phase change. This will help to better understand the extent of the cooling effects and its impact on the thermal regime of permafrost.
... Although the geophysical results are consistent with geomorphological mapping (Duffek et al., 2023b) and the geological map (LFU, 2021), they must be treated with caution due to the nature of geophysics (Otto and Sass, 2006;Schrott and Sass, 2008). The results could be combined with other geophysical methods (Sass, 2006;Tábořík et al., 2017;Břežný et al., 2021;Duffek et al., 2023a) such as shallow seismic refraction as recommended by e.g. ...
The Bohemian Forest was glaciated during Pleistocene cold periods. However, opinions on the extent of the glaciation of this mountain range are divided and vary throughout the scientific communities on either side of the Czech/German border. There is the hypothesis of a more extensive glaciation, which is to some extent supported on the Bavarian side, but Czech researchers rather incline to the existence of individual cirques or small valley glaciers. We present the results of geophysical analyses using electrical resistivity tomography carried out in the vicinity of Kleiner Rachelbach cirque. The aim was to examine the extent of the glacial sediments and thus, prove or disprove the hypothesis of a more extensive glaciation. We were seeking to find geophysical manifestations of the glacial sediments (determined on the basis of a literature review, the official geological map and our research) in a moraine complex and beyond it, where long valley glaciers are assumed to have extended. We observed such a manifestation only in the moraine complex. We can thus disprove the hypothesis of an extensive glaciation in the vicinity of Kleiner Rachelbach cirque.
... The most commonly used methods for solving the landslide problem in geophysical studies are electrical resistivity and seismic methods. Thanks to these two methods, the underground section of the region where the mass movement occurs can be produced and the slip surfaces of the movement can be determined clearly (Otto and Sass 2006;Ristic et al. 2012;Uyanık 2015). ...
Examining the mass movements caused by landslides with different geodetic deformation analyses makes it possible to minimize the possible losses. This study aims to perform different geodetic deformation analyses in a paleo-landslide area in Maçka district, one of the districts where landslides are most common. In this context, a total of 24 points, 7 reference and 17 object points, were created. Using a geodetic network, whose reliability and sensitivity optimization was completed, 5 periods of GNSS measurements were made between 2019 and 2021. The mass movements occurring in the study area were first determined using the static deformation model. Then, a kinematic deformation model based on Kalman filtering technique was applied to detect mass movements. Finally, the dynamic deformation model was obtained by considering the monthly total precipitation factor as the external force. According to the results, it has been determined that there are significant mass movements in both horizontal and vertical directions, especially in regions where the slope is high. In addition, the results obtained from the dynamic deformation model were found to be compatible with the results obtained from other deformation models. In addition, geophysical measurements were made in parallel with the geodetic measurements in the study area. As a result of geophysical measurements, the geophysical anatomy of the underground was revealed. This anatomy allowed the results obtained from geodetic measurement methods to be evaluated from a wider perspective. It has been determined that the results obtained from both geodetic and geophysical measurement methods are compatible with each other.
... Practically, the only non-invasive approach (in cases where drilling and digging are not possible) to investigate the block accumulations characteristics is the use of geophysical methods. The applicability of these methods is widely demonstrated in many geomorphological studies [8][9][10][11][12][13][14][15]. The general advantages and limitations of some of these methods are summarised by refs [16][17][18][19][20][21][22][23][24]. ...
... Therefore, in Skalka site, we grounded the electrodes using sponges saturated in electrolyte (hypersaline solution) (Figure 3a) to ensure sufficient conductive contact with the surface. This approach has been previously verified [12,52]. We carried out the ERT measurements in Skalka site in 2009, and the first results were reported by ref. [53], which marked the initial stage of the block accumulation research. ...
... However, the ERT method is not fully suitable for determining the exact thickness of the block accumulation separately as exemplified by investigation of ref. [53] who provided interpretations based solely on the ERT. Such inaccurate interpretations are most likely a result of overestimated thickness of the superficial layer caused by decreasing resolution and sensitivity at larger depths and associated interpolations [12,57,89]. This confirms that the comprehensive approach presented by ref. [20,26] provided results with lesser uncertainty. ...
Understanding the internal structure of specific landforms is a crucial prerequisite for determining their origin and evolution. Near-surface geophysics represents a non-invasive way of subsurface investigation, and it can be used to describe subsurface conditions, especially in protected areas. We tested possible hypotheses of block accumulations origin and evolution by four different geophysical methods (electrical resistivity tomography [ERT], shallow seismic refraction [SSR], ground penetrating radar [GPR], and electromagnetic induction [EMI]) in the Central European Uplands. At the same time, we evaluated the applicability of geophysical methods to determine the internal structure and thickness of block accumulations. Based on the application of two suitable methods (ERT and SSR), we (1) estimated the thicknesses of block accumulations, (2) partially described their internal structure, and (3) presented the most probable hypotheses of block accumulation origin and evolution in two investigated sites.
... Some studies focus on the internal structure and thickness of such sediment deposits (Hoffmann and Schrott 2003;Sass 2008), whereas other studies aimed to quantify permafrost existence or thickness of permafrost lenses (Stiegler et al. 2014;Kellerer-Pirklbauer 2019). Otto and Sass (2006) compared three geophysical methods for talus slope investigations in the Hungerli Valley, Turtmann, Valais Alps (NWA) using ground penetrating radar (GPR), electrical resistivity tomography (ERT), and seismic refraction (SR). Their combined geophysical results produced a detailed image of the studied talus slopes and adjacent landforms. ...
The European Alps cover an area of 190,900 km2, are arcuated in the western part, extend over a length of 1200 km, are up to 280 km wide, and reach their highest elevation at Mont Blanc (4807.8 m a.s.l.). Some 19% of the area exceed 2000 m. Up to 52% consist of carbonate rocks at the surface, which is relevant for karstification processes. During the Last Glacial Maximum, 55% of the Alps were covered by glaciers whereas the remaining area was impacted by moderate to severe periglacial conditions causing the formation of remarkable periglacial landforms still visible today particularly at the Alpine margin. During the Late Glacial period, previously glaciated areas were reshaped by periglacial processes forming for instance rock glaciers and solifluction landforms characterising many high-elevated regions in the Alps at present. Nowadays, active periglacial processes are restricted to elevations above 2000 m, at the central Alps to above 2400 m. Around 11% of the Alps are in this active periglacial belt, constrained by the potential treeline as the lower limit and the currently glaciated areas (1% of the Alps) as the upper limit. The widespread existence of relict and active periglacial landforms in the Alps inspired research of many scholars and scientists since centuries. Even Leonardo da Vinci made some periglacial-related observations in the late fifteenth century. Despite long traditions and comprehensive experiences in periglacial landform research, future periglacial research is still needed and will help to better understand the impact of ongoing climate change on the periglacial reshaping of this remarkable mountain chain.
... Generally, the penetration depth of ERT surveys depends largely on the measurement geometry used, and specifically on the maximum separation of electrodes, although the type of electrode configuration used also have a significant effect. Resolution and sensitivity decrease rapidly with depth (Kiflu et al. 2016;Loke, 2019;Otto and Sass 2006). Both are dependent on electrode spacing and on the electrode array applied. ...
Aims
Our objective was to identify the most accurate and simple non-destructive method for visualising a tree’s root system, based on the assumption that tree physiological processes affect subsurface physical properties. To investigate this, we tested four geoelectrical methods, i.e. electrical resistivity tomography (ERT), electromagnetic induction (EMI), modified earth impedance (MEI) and ground-penetrating radar (GPR), each providing geophysical maps representing the spatial distribution of physical quantities that allow for the identification of structural and functioning roots.
Methods
The four geoelectric methods were applied to a semi-solitary 13-year-old European ash (Fraxinus excelsior) ‘Atlas’ (diameter at breast height = 15.1 cm, height = 8.3 m) situated in a 14 × 14 m plot. Subsequently, we unearthed the roots using an air spade to visualise the actual root system. A 3D model and orthomosaic of the root system was then created from 177 photographs. Finally, root-zone maps from each technique were compared with the excavated root system to determine the spatial accuracy of each method.
Results
Our results showed that the spatial accuracy of each method used to detect root system structure (conduction zones) varied widely, ranging from 12.38% for MEI, to 44.59% for GPR, 74.54% for EMI and up to 92.66% for ERT. The results for functioning roots (absorption zones) also varied along the same gradient, ranging from 14.06% for MEI, 50.63% for GPR, 84.64% for EMI and up to 105% for ERT.
Conclusions
Based on our case study, ERT, followed by EMI, provided the most reliable reconstruction of a tree’s root system, with EMI successfully detecting many individual absorption zones.
... For instance, geotechnical engineering, environmental groundwater aquifer characterization (Nugraha et al. 2021), mineral explorations, and geomorphology that include sediment thickness. Geophysical exploration methods have acquired great importance, because they are nondestructive and reliable, and are often less expensive I J O G compared to other methods such as drillings, fast field application, and high resolution data collection in short time (Otto and Sass, 2006;Al-Amoush and Mashagbeh, 2009;(Farid et al. 2021). ...
DOI:10.17014/ijog.9.3.355-369In this study, an integration of Electrical Resistivity Tomography (ERT) and Time-Domain Electromagnetic (TDEM) methods have been used to investigate the superficial deposit characterization at Al al-Bayt University area. ERT and TDEM results helped to delineate the subsurface geology, and to map soil and basalt flow thicknesses as well as subsurface geological structures. Superficial deposit thicknesses were found in the range of 9 to 16 m, whereas the underlying basalt flow thickness was found to vary from a few meters in the western part to more than 60 m in the most eastern part of the studied area. The ERT results permitted a subsurface lithology characterization of the upper 35 m below ground surface (mbgs), the soil/superficial deposit resistivity was found in the range of 5 ̶40 Ohm.m, and thickness within 12 ̶ 15 mbgs. The TDEM results permitted mapping and delineating the subsurface geology up to 80 m, and allowed mapping the main subsurface structures. The soil/superficial deposits have resistivity in the range of 10 to 90 Ohm.m and the thickness in the range of a few meters up to 15 m. The study recommends a detailed geophysical study before starting any type of geo-engineering construction.
... It was carried out multi-methodical geophysical studies containing electrical resistivity, GPR, and seismic methods [27]. It was also carried out similar studies on landslide investigation [28,29]. In these studies, the sliding surface of the landslides and the flow direction properties of the landslide material were generally determined by 2D (two-dimensional) and 3D (three-dimensional) geophysical sections. ...
The study area covers approximately 200x250 m 2. This area is one of the most active locations with the greatest landslide displacement amount. This study aims to determine the depth of the sliding surface with geophysical (seismic refraction tomography (SRT) and ground-penetrating radar (GPR)) methods. The results of the TUBITAK-111Y111 project were also used in this study. According to the geophysical results, three layers with average seismic P-wave velocities (V P) of 600, 1200, and 2100 m/sec were identified within an investigation depth of approximately 20 m. It was determined that the depths of the sliding surface changed between approximately 3 to 7 m and seismic velocities were lower than 600 m/sec from these depths to the surface. The geophysical results demonstrated that the landslide type was planar sliding, the sliding direction was S-SE, and the tilt of the geological layer was in the same direction with the topographic slope, mostly bigger than 5 0. It was observed that deformations in the landslide mass were caused by the geological unit, the layer or topographic slope, and precipitation. According to these results the landslide activity may continue in the landslide area and in the study area in the future. Therefore, as a result, it was also expressed that the study area contains the risks and the natural/anthropogenic hazards because the findings show that the settlement area and urban constructions are under threat in the west of Koyulhisar town center.
... The evaluation of the talus slope is one of the most important slope surface processes on the exposed hard rocks in mountainous regions (Statham, 1976;Evans and Hungr, 1993;De Blasio and Saeter, 2015). Recently, research on rockfall activity in outcrop-talus slope systems has been conducted mainly for the European Alps (Jomelli and Francou, 2000;McCarroll et al., 2001;Otto and Sass, 2005;Sanders, 2010;Sanders et al., 2014;Colucci et al., 2016;Vehling et al., 2017;Messenzehl et al., 2018;Hendrickx et al., 2020), the Japanese Alps (Imaizumi et al., 2020), and some mountains in the UK (Curry and Morris, 2004), North America (Veilleux et al., 2020;Collins et al., 2022), and the Tibetan Plateau (Wan et al., 2021). ...
Hillslope processes and mass movement are key issues in the analysis and evaluation of geological disasters in mountainous regions. A rockfall-dominated talus slope exhibits a typical outcrop–talus slope system as the product of detached boulders and rock fragments. The Zongling rockfall zone is one of the most active outcrop–talus slope systems in southwest China, and it provides a representative case study on the assessment of rockfall hazards at the base of talus slopes. In this article, the formation mechanism and failure mode of this rock-talus system were studied using field investigation, remote sensing image analysis, and numerical simulation. The findings reveal that the lithology and rock mass structure of the study site are controlling factors for outcrop retreat and the progressive development of talus deposits. This process is intensified by rainfall and mining activities. Boulder accumulation on the platform at the middle section of the talus slope serves as top loading for the slope mechanical system. During the boulder–ground interaction, the rockfall impact acts as toe cutting to change the geometry and mechanical balance of the talus slope. It was found that toe cutting significantly influenced the slope stability, which led to a decrease in the antisliding force of the slope. The slope failure induced by rockfalls occurred with the combined effect of top loading and toe cutting on this talus slope. During rockfall prevention and mitigation in this region, the government and residents should consider the geodisaster chain, as this relates to the impact of rockfall on talus slopes, in addition to the risk of damage due to the rockfall trajectory.
