230 results on '"Loew, Simon"'
Search Results
202. Analysis of Lunar Rockfalls
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Bickel, Valentin, Loew, Simon, Manconi, Andrea, Mall, Urs, and Lapôtre, Mathieu
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Rockfall ,Weathering ,Remote Sensing ,Moon ,Deep Learning ,Erosion ,Lunar exploration ,Data processing, computer science ,Natural sciences ,ddc:520 ,ddc:500 ,ddc:004 ,Astronomy, cartography ,FOS: Natural sciences - Abstract
Past exploration missions have revealed that the lunar topography is eroded through mass wasting processes such as rockfalls, similar to Earth. Despite the abundance of remote sensing and in–situ data many questions about the occurrence and characteristics of lunar rockfalls remain unanswered: Why do lunar rockfalls occur? What endo- and exogenic processes drive lunar rockfalls? What can these processes tell us about the geologic activity and evolution of the Moon? What can rockfall tracks teach us about the shallow lunar regolith and its interaction with the space environment? To help address these questions, we develop deep learning-driven algorithms that allow us to automate the detection and mapping of rockfalls in Lunar Reconnaissance Orbiter’s Petabyte-scale image archive - a uniquely rich resource that has barely been exploited by previous work. Our convolutional neural networks achieve human-level detection performance while reducing the required processing time by several orders of magnitude. By applying transfer learning principles we further boost the performance of our detectors and make them robust enough to map rockfalls on other bodies across the Solar System as well, such as Mars, Ceres, and comet 67P. Using such multi-domain trained algorithms we conduct the first-ever, global scan of the lunar surface and derive the global distribution of rockfalls on the Moon, identifying more than 130,000 individual rockfalls. The global distribution of rockfalls is highly heterogeneous, where the vast majority as well as the highest spatial concentrations of rockfalls occur in young impact craters and on equatorfacing slopes with large thermal gradients. This indicates that rockfall occurrence is mainly controlled by erratic impacts and continuous solar-driven thermal fatigue. We discover that rockfalls occur even in the oldest, pre-Nectarian lunar terranes, indicating that the identified processes - particularly small-scale meteoritic impacts - drive erosion over billions of years. We do not observe significant clusters of rockfalls in the proximity of visible volcanic and tectonic features which suggests that seismic activity has not been a major, global driver of lunar rockfall in the Moon’s recent geologic past. Using satellite images of rockfall boulders and their tracks, we further develop a method to estimate the regolith surface strength and geomechanical properties of yet unexplored regions, such as the polar permanently shadowed regions and large pyroclastic deposits, directly supporting humanity’s current efforts to continue the exploration of the Moon and beyond. This dissertation demonstrates the enormous potential of deep learning-driven applications for planetary science and reveals new insights about the weathering, erosion and evolution of airless planetary bodies in our solar system.
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- 2021
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203. High-resolution monitoring and analyses of thermo-hydro-mechanical rock slope processes during glacial retreat (Aletsch Valley, Switzerland)
- Author
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Hugentobler, Marc, Loew, Simon, Aaron, Jordan, Moore, Jeffrey, and Farinotti, Daniel
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Earth sciences ,ddc:550 - Published
- 2021
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204. Remote Sensing Analyses of Slope Instabilities in Northwestern Bhutan
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Dini, Benedetta, Loew, Simon, Manconi, Andrea, and Wasowski, Janusz
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Earth sciences ,Landslides - InSAR - Bhutan - reversible deformation ,ddc:550 - Abstract
Slope instabilities adversely affect mountainous regions by posing direct and indirect hazards. Landslides can evolve in catastrophic failures that can directly cause loss of lives, damage to properties and to critical infrastructure. Moreover, indirect effects can cause destruction of arable land and, in case of landslide damming of rivers, subsequent floods that can have an impact a long way downstream of the landslide site. A large-scale overview of unstable slopes in mountainous regions is therefore important in order to understand the spatial distribution, to investigate the activity, to create a basis for landslide hazard assessment and to further the science regarding the predisposing and controlling factors. Bhutan was chosen for this study given its relatively poor regional knowledge of unstable slopes, despite its proneness. The main purpose of our work is to understand the spatial distribution of past large rock slope movements in the region, to quantify the recent rates of displacements and to investigate the structural and geological controls. Given the inaccessibility of the region and the large scale of the study, we used remote sensing techniques through all stages of our investigations. In particular, a combination of optical images and high-resolution digital surface model analysis and synthetic aperture radar differential interferometric (DInSAR) techniques was used. The use of DInSAR allowed also to image, quantify and discern slope displacements that are related to soil slide/creep or rock glaciers creep, moreover, it allowed to illuminate areas with reversible displacements related either to freeze-thaw cycles in the permafrost region, or to groundwater table seasonal fluctuations at lower elevations. We produced some new datasets for the region including: 1) a regional rock slope instabilities inventory based on optical images, 2) a rock glaciers inventory based on optical images, 3) an active slope instabilities inventory based on the analysis of individual interferograms, 4) an inventory of active slope instabilities based on multi-temporal DInSAR analyses which includes gravitational and reversible deformation, 5) a regional structural inventory largely based on remote sensing mapping with the inclusion of some in-situ measurements. We present the analysis of individual interferograms aimed at the identification of actively unstable slopes. We perform a geomorphological classification based on the landslide types and we propose a new method to assess the activity likelihood uniquely based on remote sensing techniques. This methodology is based on an articulated decision tree, which takes into account the number of sensors used for the analysis, the number of interferograms in which displacements are identified, the satellite orbit geometry, vegetation cover, geometrical distortions, estimated velocity and temporal coverage of the data. This method allows lowering or maintaining the confidence regarding the activity of each identified slope instability by analysing what would be the detection expectation. It maximises the III level of information retrievable from standard interferometric analyses and is new and applicable to other mountainous regions. We use multi-temporal analyses based on SAR data to show the potential of the technique in identifying specific instabilities of which no previous knowledge existed. Here we show a methodology to combine a model-based atmospheric correction and an empirical correction to remove stratified, long wavelength signals from the cumulative displacement maps, without an atmospheric correction on the interferograms used to generate them. This method takes advantage of the local nature of slope processes leading to surface displacements to separate them from the long-wavelengths signals related to artifacts. This method allows to identify small-scale reversible displacements related with freeze-thaw cycles in the permafrost region and, moreover, it provides insights into the possibility of observing the dynamics of natural annual ground water table variations on valley flanks, which, had not yet been explored with multi-temporal satellite based InsAR analyses. We show the analysis performed with the combination of our structural dataset and landslides dataset aimed at investigating predisposing factors to large rock slope instabilities in the region. The methodologies developed here involve the generation of a compound structural dataset that makes use of different sources of information. The latter include remotely mapped fault traces and planar valley flanks, but also some field measurements of foliation and faults. The methodology used to compile this dataset addresses the biases deriving from uneven sampling of the different data types across the area and allows to make the dataset more balanced for systematic kinematic analyses. We apply kinematic analyses across the structural domains identified in the study region in a probabilistic way, in order to investigate the regional structural control on large rock slope instabilities formation. These methodologies are also new, and applicable to other mountainous regions where remote sensing analyses are the main source of information. We identify a structural and lithological control on rock slope instabilities across large parts of the study region. A higher predisposition to failure seems to be associated with the presence of specific sets of regional faults and foliation structures. The average orientation of one of such fault sets corresponds to the orientation of the Lingshi fault, a major known structure in the northwest of the region. Moreover, there seems to be a lithological control both on past rock slide activity and on more recent activity in association with shales, quartzite and limestone belonging to the Tethyan sediments and found in the northwest of the region. The analysis by means of DInSAR of rock slope activity in the recent past (our observation window is between 2006 and 2011) shows that the majority of active rock slope instabilities identified have rates which correspond to the slow to very slow categories, with maximum displacement rates of up to 160 mm/year, with only very few exceptions. IV These findings, combined with the field observations of a large number of past rock slide deposits, covered by thick soils, point to the fact that active unstable rock slopes are less abundant in the region in recent times than in the past. We postulate that this may be related to the lack in recent times of major earthquakes that could have previously caused widespread landslide activity at a given point in time. We have also observed that rock glaciers in northwestern Bhutan creep downslope with velocities that are on the whole lower than what has been observed in the Alps in recent years. This could be due to either a less pronounced recent warming trend than at higher latitudes or to less water being available to penetrate into the frozen unconsolidated material supersaturated with interstitial ice and to deeper subsurface shear horizons.
- Published
- 2020
205. Internal structure and deformation of an unstable crystalline rock mass above Randa (Switzerland): Part II — Three-dimensional deformation patterns
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Willenberg, Heike, Evans, Keith F., Eberhardt, Erik, Spillmann, Thomas, and Loew, Simon
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ENGINEERING geology , *CRYSTALLINE rocks , *ROCKSLIDES , *INCLINOMETER , *ROCK deformation , *ROCK mechanics - Abstract
Abstract: The monitoring of slope displacements over time provides the basis for most rockslide early warning systems, yet the prediction of catastrophic failure from these records is highly problematic and tenuous, especially if the underlying kinematics and instability mechanism are poorly understood. An example is the moving slope above the town of Randa in the Swiss Alps. This slope is considered typical of those in crystalline rock that lacks a natural, highly persistent, weakness plane dipping towards the valley that can serve as a through-going detachment surface for kinematic release. In Part I (the companion paper to this), the findings from a comprehensive geological and geophysical investigation to image the internal structures of the unstable rock mass were presented. In this paper we develop a kinematic model that describes the pattern of displacement vectors for the rock mass along these structures, both on surface and at depth. The displacements were estimated from 5 years of data from an extensive monitoring system which included surface geodetic and crackmeter measurements, borehole inclinometer and extensometer measurements (up to 120 m depth), and microseismicity. The results showed that the displacement field is highly heterogeneous. Internal deformation is accommodated by both shear and opening-mode dislocation of faults and fracture zones which dip moderately to steeply into the slope. Microseismicity is most intense near the front of the scarp where surface translation in large part reflects the toppling of blocks accommodated by slip along the steeper dipping fractures. The small displacement rates at the study site of up to 2 cm/year coupled with a modest deviation of up to 15° from vertical of the boreholes posed severe problems for the estimation of horizontal displacements from the inclinometer data. We describe the error analysis of these data in some detail since it is relevant for similar installations elsewhere. Conclusions drawn from this work highlight the importance of integrating various types of data in order to better understand the complex block-kinematic processes whose evolution governs the long-term progressive failure of unstable rock slopes. [Copyright &y& Elsevier]
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- 2008
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206. Hydro-Mechanical Responses of a Fractured Rock Mass during Decameter-Scale Hydraulic Stimulation Experiments
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Krietsch, Hannes, Loew, Simon, Gischig, Valentin, Amann, Florian, and Renner, Jörg
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Earth sciences ,ddc:550 - Published
- 2019
207. Monitoring and analysis of interactions between the retreating Aletsch glacier and adjacent rock slope instabilities
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Glueer, Franziska, Loew, Simon, Zangerl, Christian, and Manconi, Andrea
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Digital image correlation (DIC) ,Paleontology, paleozoology ,Remote sensing ,Total Station Monitoring ,Earth sciences ,DSGSD ,Geomoprhologic mapping ,Paraglacial rock slope mechanics ,ddc:560 ,ddc:550 ,Landslides - Abstract
The valley flanks around the Great Aletsch Glacier (Valais, Switzerland) contain several rock slope instabilities, concentrated around the current extent of the glacier tongue. These alpine rock slopes have been exposed to cycles of glaciation and retreat, leading to changing slope geometries and stress conditions. Processes leading to the formation of rockslides, rock avalanches or progressive slow movements with time since deglaciation, the impact of cyclic ice-loading and the dominant driving mechanisms have been studied for many years but are partly still unexplained. Additionally, the triggering events and causes of failures of landslides in deglaciated or currently deglaciating valleys are poorly understood. Often, the absence of observable triggering mechanisms presents a significant problem for hazard management and science. Better knowledge of subsurface processes, even if only reconstructed from surface observations and deformations, is essential to improve our understanding of paraglacial rock slope processes. During the course of this PhD thesis the extraordinary activation of the deep-seated gravitational slope deformation (DSGSD) of Moosfluh was witnessed and failure mechanisms, spatial and temporal displacement patterns and paraglacial conditioning factors were studied in great detail. During the first stage of this PhD thesis, a very accurate displacement monitoring system was developed for the high alpine environment of Aletsch. This monitoring system consists of two automatic total stations coupled with Global Navigation Satellite System (GNSS) sensors, meteo sensors and a webcam. It is designed to work all year in harsh conditions with extreme temperature changes, heavy rainfall and snowstorms. The reflectors and the stations have to be protected against rockfall and snow avalanches. In the first phase of this PhD the focus was set on the design and implementation of this total station monitoring system and the processing of high accuracy 3D displacement data. We identify key monitoring goals, discuss stability of pillar foundations, the influence of protective housing and compare calculated to observed accuracies. The selected total station monitoring is based on a lightweight but stable foundation and a total station instrument protection without optical refraction of the light beam and mechanic protection of reflector prisms. The selected monitoring sites presented in this study do not only focus on instabilities, like the large and rapid rock slope instability of Moosfluh and the slow‐moving instability of Driest, but also on seasonally reversible rock slope deformations along several profiles in stable rock across the Great Aletsch Glacier valley. During the second stage of this PhD thesis, the paraglacial history and structure of the Moosfluh Landslide from 1850 to 2016 was investigated. The geomorphological evolution of the Moosfluh slope was reconstructed with photogrammetric models generated from historical aerial photographs. This multi-temporal landslide analysis showed that the bulk displacement and internal deformation at Moosfluh is accommodated mainly by toppling composed of shear slip along the steeply dipping Alpine foliation and extensional faulting in the crest area. Numerous uphill-facing scarps, scarps, tension cracks, toe bulging, graben-structures and displacement of moraine deposits, evidence post-Egesen landslide displacements and an acceleration of movements since the LIA and especially since 2007. Together with digital image correlation and total station monitoring, an increase of displacement rates from a few millimeter per year until 1990, to several meter per day in September 2016 was retraced. Balanced longitudinal sections through the Moosfluh Landslide are based on observed ground surface displacements and geometrical and mechanical constraints. A simple limit-equilibrium analysis helped explore changes in rock slope stability caused by glacial ice retreat and changing groundwater levels, showing that the simulated factor of safety drops non-linearly from the LIA maximum (1.12) to the year 2007 (1.02), when the ice thickness at the landslide toe melted down to 100 m. During the third stage of my PhD thesis, the unexpected acceleration of the Moosfluh DSGSD, which started in September 2016 and posed hazards to a nearby cable car station and an adjacent dammed lake 4 km downstream of the Moosfluh slope, was studied in detail. With our high accuracy displacement monitoring system, installed in 2013 and 2014, it was possible to record the progressive evolution of the Moosfluh Landslide from toppling to sliding in unprecedented detail. The formerly slowly moving toppling mode DSGSD of about 100 Mio m³ and up to 170 m depth developed into a fast moving landslide through the formation of several shallow (30-50 m) secondary slides. These secondary landslides started their development at the toe of the slope, and evolved upslope with time, as evidenced by time series of surface displacement vectors. Digital image correlation (DIC) of webcam images and helicopter-borne photogrammetry allows for detailed mapping of landslide boundaries and active morphological features. For kinematic analyses of toppling and sliding block a new method called ‘plunge angle analysis’ was developed. This approach allows to quantify the underlying failure mechanisms (toppling, sliding and mixed mode deformations) and assign depths and inclination angles of toppling/sliding planes from measured surface displacement vectors. The analysis of displacement vector time series allows the identification of landslide volumes and rupture plane depths. The results and developed method provide a better understanding not only of the Moosfluh Landslide but of all slopes affected by mixed toppling and sliding failure mechanisms. This study assembled a unique dataset documenting the development of a 'paraglacial' landslide from a slow moving DSGSD into an active and hazardous landslide. Combining multiple methods for reconstruction and current surface deformation monitoring strengthened our understanding of mechanisms and long-term controls occurring in currently deglaciating environments. In addition this thesis provides a new basis for implementing and operating a surface deformation monitoring system in high alpine environment, understanding the role of glacial ice load on rock slope instabilities and assessing present day hazards of mass movements in which toppling and sliding mechanisms coexist.
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- 2019
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208. Linkage between fracture network, stress heterogeneities and induced seismicity in deep geothermal reservoirs
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Afshari Moein, Mohammad J., Loew, Simon, Valley, Benoît, Evans, Keith, and Bour, Olivier
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Earth sciences ,ddc:550 - Published
- 2018
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209. Monitoring and analysis of active rockslide-glacier interactions (Moosfluh, Switzerland).
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Storni, Enea, Hugentobler, Marc, Manconi, Andrea, and Loew, Simon
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LANDSLIDE hazard analysis , *LANDSLIDES , *DIGITAL image correlation , *ROCK slopes , *VISCOSITY , *VECTOR fields , *SLOPE stability - Abstract
Valley glaciers have traditionally been expected to significantly influence the stability and movement rates of adjacent paraglacial landslides. However, detailed studies related to the mechanical and displacement interactions between glacier ice and unstable rock slopes are very rare. Here we present a detailed in-situ investigation of the spatial variations of the displacement field of the Great Aletsch Glacier in the surroundings of a large active instability, i.e., the Moosfluh Landslide, a Deep-Seated Gravitational Slope Deformation, with superimposed large (1–5 million m3) secondary rockslides formed during fall 2016. We performed repeat UAV-based photogrammetric surveys during ~3 days (74 h) and applied Digital Image Correlation techniques to record high-resolution surface displacement vector fields of the landslide, stable slopes and adjacent glacier. Our results show that the secondary rockslide adjacent to the glacier is composed of two parts of 1.5 and 2.8 million m3 volume respectively, showing significant differences in mean displacement velocities (0.4 and 0.9 m in 74 h respectively, excluding rapid movements from detached blocks). Both rockslide compartments induce clear deflections of the glacier flow field, moving with a maximum velocity of about 0.3 to 0.4 m in 74 h. This influence is highest near the ice-contact boundary and decreases within a distance of about 100–200 m from the rock slope instability. We investigate the viscous forces at the landslide/glacier contact using a straightforward analytical model for an incompressible rockslide block sliding along a planar, cohesionless surface into ice. These forces are then applied to a slope stability model based on the limit equilibrium concept, representing the real geometry at the interface boundary to quantitatively explore the true buttressing effects of valley glaciers on an already moving slope instability. We show that the viscous ice deformation plays an important role in mediating the displacement velocities of landslides in unstable conditions, while, on the other hand, the slope support from the valley glacier has very little influence on the stability of the investigated rockslides. As most valley glaciers are currently strongly retreating due to global warming, uncovering significant numbers of pre-LIA slope instabilities, this detailed investigation provides important hints on their potential displacement behavior. Understanding the factors controlling landslide velocity is of great importance for hazard analyses and early warning. Hence, this study has implications beyond academic interest, e.g., for the planning and operation of alpine infrastructure, such as cable cars or hydropower systems. • We monitor glacier displacement fields at contacts to stable slopes and an active rockslide. • Distortions of glacier displacements fields extend over 100-200 m. and correlate with variations in rockslide velocity. • A simplified analytical model with viscous ice forces can reproduce observed rockslide velocities. • Limit equilibrium analyses demonstrate negligible effect of glacial debuttressing on mature rockslide stability. [ABSTRACT FROM AUTHOR]
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- 2020
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210. Beyond debuttressing: Thermo-hydro-mechanical rock slope damage during glacial cycles
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Grämiger, Lorenz, Loew, Simon, Moore, Jeffrey, Gischig, Valentin, and Korup, Oliver
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Earth sciences ,ddc:550 ,engineering geology - Abstract
Cycles of glaciation drive in-situ stress changes in underlying bedrock as glaciers advance, erode, and retreat, generating damage in adjacent rock slopes and influencing paraglacial slope stability. Glacial debuttressing is frequently implicated as a trigger for paraglacial rock slope failures, despite commonly observed large lag-times between deglaciation and the timing of failure and often without clear mechanical reasoning. Rock slope damage generated during glacial cycles is hypothesized to have a strong role in preparing rock slope failures, however, the mechanics of paraglacial rock slope damage remain poorly characterized. Glacial cycles mechanically load and unload proximal rock slopes by the changing weight of ice, and in addition produce strongly varying thermal and hydraulic rock-surface boundary conditions tied to the fluctuating glacier. Bedrock beneath temperate glacier ice maintains near isothermal surface temperatures at ~0 °C. Glacier retreat exposes rock walls to new thermal boundary conditions with strongly varying daily and seasonal cycles, a transition we term paraglacial thermal shock. Temperature changes generate thermal strain, inducing thermo-mechanical stresses capable of generating rock mass damage. In addition, high subglacial water pressures near the ice overburden level prevail at the base of temperate glaciers, and affect groundwater conditions in proximal valley flanks. Groundwater recharge by precipitation and snowmelt raises the water table seasonally, which is superposed on changes in hillslope groundwater tied to varying glacial ice elevations. Changing cleft water pressures control effective stresses and the strength of rock mass discontinuities. Together, these thermo-hydro- mechanical stresses act in concert with glacial loading cycles to generate rock slope damage, preparing slopes for future failure. We study thermo-hydro-mechanical induced stresses and resulting rock slope damage during repeat glacial cycles in the valley of the Great Aletsch Glacier in Switzerland. Following Lateglacial deglaciation, the surrounding valley rock slopes in the Aletsch region experienced several minor glacier cycles during the Holocene. The foliated gneissic rock mass of the Aletsch valley contains several large rock slope instabilities with a concentration around the retreating, present-day glacier tongue. Surface exposure dating of the Driest instability head scarp reveals a Mid-Holocene initialization age (7.4 ± 0.7 ky), matching post-Egesen / pre-Little Ice Age relative ages for the majority of other rock instabilities in the Aletsch Valley. To investigate progressive rock slope damage induced during glacier cycles, we used detailed, conceptual numerical models closely based on our Aletsch Valley study area. Modeled glacier scenarios represent mapped ice fluctuations at Aletsch, while rock mass strength parameters applied in our models are based on local rock mass characterization. Ground surface temperature measurements, monitoring of subglacial water pressures in ice boreholes, regional spring-line mapping, and monitoring of rock slope deformation at Aletsch each contribute to parameterizing and validating our thermal and hydraulic model boundary conditions. Our simulations reveal that purely mechanical loading and unloading of rock slopes by ice during glacial cycles generates relatively limited new damage. This result supports our view that glaciers make a poor buttress for adjacent slopes due to the ductile behavior of ice over long time scales. However, ice fluctuations in our models do increase the criticality of fractures in adjacent slopes (bringing them closer to the failure envelope), which may in turn increase the efficacy of additional fatigue processes. On the other hand, bedrock erosion during glaciation (i.e., rock debuttressing) promotes significant new rock slope damage during first deglaciation. The amount of initial damage, inherited from pre-glacial, ice-free topographic and in-situ stress conditions, strongly controls the susceptibility of the slope to new damage from ice loading. The slope response during glacial cycles is path-dependent and varies in damage kinematics: glacier advance in our models enhances toppling failure while glacial retreat promotes sliding. Changing thermal boundary conditions during glacier retreat and advance in our models affects the temperature regime in the adjacent rock slopes. Thermal strain from long-term temperature changes induces stresses at depths exceeding 100 m, generating significantly more rock slope damage than predicted for purely mechanical loading cycles. Thermal expansion of the rock mass due to warming after glacier retreat causes increased stresses propagating fractures, while cooling during glacier advance results in contraction, reducing joint normal stresses and promoting toppling. First time exposure to seasonal temperature cycles during deglaciation induces a strong but shallow damage front that follows the retreating ice margin. Glacial loading cycles in parallel with thermal stresses (i.e., thermo-mechanical fatigue) are capable of generating significant rock slope damage. We extend our models by accounting for changing groundwater conditions in proximal valley rock slopes tied to high subglacial water pressures. Glacier loading cycles in parallel with long-term mountain water table variations generate substantial fracture propagation. Major damage occurs during initial ice occupation and first glacier retreat, while subsequent readvances result in minor damage. Superposition of annual groundwater cycles (i.e., hydro-mechanical fatigue) strongly increases rock slope damage during glacial loading cycles, destabilizing the toppling-mode valley flank in our models. The kinematics and dimensions of the predicted instability closely resemble observed characteristics of major landslides in the field at Aletsch. Our results extend simplified assumptions of glacial debuttressing, demonstrating in detail how thermo-hydro-mechanical stresses acting in concert with glacier cycles drive progressive rock mass failure preparing future paraglacial slope instabilities.
- Published
- 2017
211. Characterization of CO₂ plumes in deep saline formations using fluid pressure tomography
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Hu, Linwei, Loew, Simon, and Helmig, Rainer
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Earth sciences ,ddc:550 - Published
- 2017
212. Processes Controlling The Distribution Of Permeability In Crystalline Rocks In The Upper 2 Kilometers Of The Earth’s Crust
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Achtziger, Peter, Loew, Simon, Faulkner, Daniel, and Mariethoz, Gregoire
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Earth sciences ,ddc:550 - Published
- 2017
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213. Thermal Tracer Tomography to Characterise Aquifer Heterogeneity
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Somogyvári, Márk, Loew, Simon, Bayer, Peter, Brauchler, Ralph, and Bour, Olivier
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Earth sciences ,ddc:550 - Published
- 2017
214. Classification of slope processes based on multitemporal DInSAR analyses in the Himalaya of NW Bhutan.
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Dini, Benedetta, Daout, Simon, Manconi, Andrea, and Loew, Simon
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ROCKSLIDES , *BRAIDED rivers , *WATER table , *ROCK glaciers , *ROCK slopes , *GLACIERS , *HOME range (Animal geography) - Abstract
Slope deformation in mountainous terrain can be driven by different processes, the nature of which is either gravitational and irreversible or seasonal and reversible, the latter induced by permafrost variations or by hydromechanical or thermomechanical effects. The importance of identifying such deformations is not only related to the hazard they can pose, but also to the understanding of changes that permafrost or local hydrological conditions undergo. Here, we carry out a multi-temporal InSAR analysis over a mountainous area 8000 km2 large, straddling north-western Bhutan and southern Tibet. We propose a methodology to separate locally deforming areas from the effects of long-wavelength signals through the analysis of the spatio-temporal behaviour of 4-years long time series of surface displacements. We present the mapping of hundreds of small-scale features that appear to be actively deforming, as well as several examples of reversible deformation rarely detected at this scale in such a challenging and vast region. The analysis of the multi-annual trend of ground deformation shows a relatively small number of irreversible gravitational movements clearly related to rock slides which attests a low level of recent activity of large rock slope instabilities in the region. In the southernmost, lower elevation parts of the study area, we quantify reversible surface displacements with amplitudes ranging between 5 and 17 mm, and showing maximum displacements towards the satellite in summer months, thus compatible with hydro-mechanical effects related to groundwater table variations. In addition, the ground movement induced by the active layer's response to thawing and freezing over the gentler slopes and high-elevation permafrost regions of Bhutan and southern Tibet is on average around 10 mm, with maxima up to 28 mm. The localised displacements appear to be largely associated to braided stream plains, glacier outwash plains or low angle, fine sediment covered slopes. • Inventory of gravitational and reversible surface displacements for NW Bhutan • Classification of slope processes made on the basis of time series trends • Reversible, mostly vertical deformation, observed in the permafrost region • Reversible deformation with horizontal component observed at lower elevations • Rock glaciers appear to have lower creep rates than in the Alps. [ABSTRACT FROM AUTHOR]
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- 2019
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215. Evaluation of the hydro-mechanical properties and behavior of Opalinus Clay
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Wild, Katrin M., Loew, Simon, and Elsworth, Derek
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PERMEABILITY (ROCK FORMATION, HYDROLOGY) ,DURCHLÄSSIGKEIT (GESTEINSSCHICHTEN, HYDROLOGIE) ,PHYSICAL ROCK PROPERTIES (PETROGRAPHY) ,UNTERGRUNDLAGERUNG RADIOAKTIVER ABFÄLLE ,PHYSIKALISCHE GESTEINSEIGENSCHAFTEN (PETROGRAPHIE) ,EXPERIMENTAL GEOLOGY (EARTH SCIENCES) ,EXPERIMENTALGEOLOGIE (ERDWISSENSCHAFTEN) ,ROCK-FLUID INTERACTION (PETROGRAPHIE) ,STRESS-STRAIN BEHAVIOUR (ELASTOMECHANICS) ,CLAY (PETROGRAPHY) ,SPANNUNG-DEHNUNGSVERHALTEN (ELASTOMECHANIK) ,Earth sciences ,ROCK-FLUID INTERACTION (PETROGRAPHY) ,TRIAXIALVERSUCH ,ddc:550 ,UNDERGROUND STORAGE OF RADIOACTIVE WASTES ,TRIAXIAL TEST ,TON (PETROGRAPHIE) - Published
- 2016
216. Hydro-mechanically coupled processes in heterogeneous fractures: experiments and numerical simulations
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Vogler, Daniel, Loew, Simon, and Zimmerman, Robert W.
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FRACTURED ROCKS + CLEAVAGE (GEOLOGY) ,BRUCHFESTIGKEIT (ELASTOMECHANIK) ,NUMERICAL SIMULATION AND MATHEMATICAL MODELING ,STRESS-STRAIN (GEOLOGIE) ,FLUIDMECHANIK ,STRESS-STRAIN (GEOLOGY) ,NUMERISCHE SIMULATION UND MATHEMATISCHE MODELLRECHNUNG ,ROCK MECHANICS (CIVIL ENGINEERING) ,GRANITE (PETROGRAPHY) ,HOT DRY ROCK, GEOTHERMAL ENERGY EXCHANGER (GEOPHYSICS) ,BREAKING STRENGTH (ELASTOMECHANICS) ,KLÜFTE + SPALTEN (GEOLOGIE) ,FELSMECHANIK (BAUINGENIEURWESEN) ,GEOTECHNIK (ANGEWANDTE GEOLOGIE UND GEOPHYSIK) ,EXPERIMENTALGEOLOGIE (ERDWISSENSCHAFTEN) ,GRANIT (PETROGRAPHIE) ,HOT DRY ROCK, GEOTHERMISCHE ENERGIENUTZUNG (GEOPHYSIK) ,FLUID MECHANICS ,ENGINEERING GEOLOGY (APPLIED GEOLOGY AND GEOPHYSICS) ,EXPERIMENTAL GEOLOGY (EARTH SCIENCES) ,Earth sciences ,ddc:550 - Published
- 2016
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217. Seismic characterization of rockslides using existing regional networks
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Dammeier, Franziska, Loew, Simon, Moore, Jeffrey R., Haslinger, Florian, and Mangeney, Anne
- Subjects
ALPEN (EUROPÄISCHE GEBIRGE) ,NATURAL HAZARDS + NATURAL CATASTROPHES ,ROCK-SLIDE ACCUMULATIONS + ROCK-AVALANCHE ACCUMULATIONS (GEOMORPHOLOGY) ,STEINSCHLAG (GEOMORPHOLOGIE) ,ALPS (EUROPEAN MOUNTAINS) ,SEISMOGRAMS/COMPOSITE RECORDINGS (GEOPHYSICS) ,ANGEWANDTE GEOLOGIE UND GEOPHYSIK/UNTERSUCHUNGSERGEBNISSE, DEUTUNG DER DATEN ,APPLIED GEOLOGY AND GEOPHYSICS/TREATMENT OF INVESTIGATION DATA AND INTERPRETATION OF DATA ,CENTRAL ALPS (WESTERN ALPS) ,SEISMOGRAMME/ZUSAMMENGESETZTE AUFZEICHNUNGEN (GEOPHYSIK) ,NATURGEFAHREN + NATURKATASTROPHEN ,STEINSCHLAGFORMEN + MURENFORMEN (GEOMORPHOLOGIE) ,ROCK-FALL + ROCK-SLIDE (GEOMORPHOLOGY) ,ZENTRAL-ALPEN (WESTALPEN) ,Earth sciences ,ddc:550 - Published
- 2015
218. Age and formation mechanisms of exfoliation joints in the Aar Granites of the Central Alps (Grimsel region, Switzerland)
- Author
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Ziegler, Martin, Loew, Simon, and Bahat, Dov
- Subjects
FRACTURED ROCKS + CLEAVAGE (GEOLOGY) ,GRIMSEL PASS (BERNESE ALPS) ,GRIMSELPASS (BERNER ALPEN) ,ABSONDERUNGSFORMEN DER GESTEINE (GEOLOGIE) ,STRUKTUR + TEXTUR + GEFÜGE (PETROGRAPHIE) ,AAR MASSIF (BERNESE ALPS) ,STRUCTURE + TEXTURE + FABRICS (PETROGRAPHY) ,Earth sciences ,JOINTING OF ROCKS (GEOLOGY) ,SECONDARY FABRICS (PETROGRAPHY) ,AARMASSIV (BERNER ALPEN) ,KLÜFTE + SPALTEN (GEOLOGIE) ,SEKUNDÄRGEFÜGE (PETROGRAPHIE) ,ddc:550 - Published
- 2014
219. Stress development and geomechanical controls on the geomorphic evolution of alpine valleys
- Author
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Leith, Kerry J., Loew, Simon, and Moore, Jeffrey R.
- Subjects
Earth sciences ,VALLEYS + TERRACES (GEOMORPHOLOGY) ,ALPEN (EUROPÄISCHE GEBIRGE) ,GEOMORPHOLOGISCHE VORGÄNGE + ERDOBERFLÄCHENFORMEN (GEOMORPHOLOGIE) ,TÄLER + TERRASSEN (GEOMORPHOLOGIE) ,ALPS (EUROPEAN MOUNTAINS) ,ANGEWANDTE GEOLOGIE UND GEOPHYSIK/UNTERSUCHUNGSERGEBNISSE, DEUTUNG DER DATEN ,APPLIED GEOLOGY AND GEOPHYSICS/TREATMENT OF INVESTIGATION DATA AND INTERPRETATION OF DATA ,GEOMORPHOLOGICAL PROCESSES + EARTH SURFACE RELIEF FORMS (GEOMORPHOLOGY) ,ddc:550 - Published
- 2012
220. Kinematics and failure mechanisms of the Randa rock slope instability (Switzerland)
- Author
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Gischig, Valentin, Loew, Simon, and Moore, Jeffrey R.
- Subjects
RUTSCHUNGEN (GEOMORPHOLOGIE) ,Paleontology, paleozoology ,ROCK MECHANICS (CIVIL ENGINEERING) ,ROCK-SLIDE ACCUMULATIONS + ROCK-AVALANCHE ACCUMULATIONS (GEOMORPHOLOGY) ,RANDA (KANTON WALLIS) ,Earth sciences ,GROUND DISPLACEMENTS (GEODESY) ,STEINSCHLAG (GEOMORPHOLOGIE) ,ddc:560 ,STEINSCHLAGFORMEN + MURENFORMEN (GEOMORPHOLOGIE) ,FELSMECHANIK (BAUINGENIEURWESEN) ,ddc:550 ,LANDSLIDES (GEOMORPHOLOGY) ,BODENBEWEGUNGEN (GEODÄSIE) ,ROCK-FALL + ROCK-SLIDE (GEOMORPHOLOGY) ,RANDA (CANTON OF VALAIS) - Published
- 2011
- Full Text
- View/download PDF
221. Structural control of multi-scale discontinuities on slope instabilities in crystalline rock
- Author
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Molina, Freddy X.Y., Loew, Simon, and Jaboyedoff, Michel
- Subjects
DIGITAL ELEVATION MODELS + DIGITAL TERRAIN MODELS (GEODÄSIE) ,GEOGRAPHICAL INFORMATION SYSTEM ,ROCK MECHANICS (CIVIL ENGINEERING) ,MATTERTAL (CANTON OF VALAIS) ,NATURAL HAZARDS + NATURAL CATASTROPHES ,GNEIS (PETROGRAPHIE) ,GNEISS (PETROGRAPHY) ,STRUKTUR + TEXTUR + GEFÜGE (PETROGRAPHIE) ,FOLIATION (GEOLOGY) ,NATURGEFAHREN + NATURKATASTROPHEN ,STRUCTURE + TEXTURE + FABRICS (PETROGRAPHY) ,Earth sciences ,STEINSCHLAG (GEOMORPHOLOGIE) ,FELSMECHANIK (BAUINGENIEURWESEN) ,SCHIEFERUNG (GEOLOGIE) ,MATTERTAL (KANTON WALLIS) ,GEOGRAFISCHE INFORMATIONSSYSTEME ,DIGITAL ELEVATION MODELS + DIGITAL TERRAIN MODELS (GEODESY) ,ROCK-FALL + ROCK-SLIDE (GEOMORPHOLOGY) ,ddc:550 - Published
- 2010
222. A three-dimensional analysis of excavation-induced perturbations in the Opalinus Clay at the Mont Terri Rock Laboratory
- Author
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Yong, Salina, Loew, Simon, and Fidelibus, Corrado
- Subjects
STRESS-STRAIN (GEOLOGY) ,STRESS-STRAIN (GEOLOGIE) ,PHYSICAL ROCK PROPERTIES (PETROGRAPHY) ,AUTOMATISCHE REKONSTRUKTION VON 3D GEBÄUDEMODELLEN UND STADTMODELLEN (GEODÄSIE) ,SEKUNDÄRE SEDIMENTSTRUKTUREN (ABLAGERUNGSMILIEU) ,PHYSIKALISCHE GESTEINSEIGENSCHAFTEN (PETROGRAPHIE) ,UNTERDOGGER (STRATIGRAPHIE) ,CLAY (PETROGRAPHY) ,MONT TERRI (CANTON OF JURA) ,BOHRLOCHBESCHREIBUNG + KERNBOHRAUFNAHME (BERGBAU) ,ddc:550 ,LOWER DOGGER (STRATIGRAPHY) ,FRACTURED ROCKS + CLEAVAGE (GEOLOGY) ,UNTERGRUNDLAGERUNG RADIOAKTIVER ABFÄLLE ,BOREHOLE DESCRIPTION + BOREHOLE DETAILS + LOGGING (MINING) ,UNDERGROUND STORAGE OF RADIOACTIVE WASTES ,MONT TERRI (KANTON JURA) ,SECONDARY SEDIMENTARY STRUCTURES (SEDIMENTARY ENVIRONMENT) ,BUILDING AND CITY MODEL RECONSTRUCTION IN 3D (GEODESY) ,KLÜFTE + SPALTEN (GEOLOGIE) ,TON (PETROGRAPHIE) ,Paleontology, paleozoology ,Earth sciences ,ddc:560 - Published
- 2007
223. The relation between natural fracturing and stress heterogeneities in deep-seated crystalline rocks at Soultz-sous-Forêts (France)
- Author
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Valley, Benoit C., Evans, Keith Frederick, and Loew, Simon
- Subjects
STRESS-STRAIN (GEOLOGY) ,STRESS-STRAIN (GEOLOGIE) ,HOT DRY ROCK, GEOTHERMAL ENERGY EXCHANGER (GEOPHYSICS) ,SOULTZ SOUS FORÊTS (FRANCE) ,GEOPHYSICAL METHODS OF WELL EXAMINATION + LOGGING (APPLIED GEOLOGY AND GEOPHYSICS) ,UPPER RHINE VALLEY, ALSACE (FRANCE) ,GEOPHYSIKALISCHE BOHRLOCHUNTERSUCHUNGSMETHODEN (ANGEWANDTE GEOLOGIE UND GEOPHYSIK) ,SOULTZ SOUS FORÊTS (FRANKREICH) ,OBERRHEINGEBIET, ELSASS (FRANKREICH) ,HOT DRY ROCK, GEOTHERMISCHE ENERGIENUTZUNG (GEOPHYSIK) ,Earth sciences ,ddc:550 - Published
- 2007
- Full Text
- View/download PDF
224. Analysis of surface subsidence in crystalline rocks above the Gotthard highway tunnel, Switzerland
- Author
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Zangerl, Christian Josef, Eberhardt, Erik, Lombardi, Giovanni, and Loew, Simon
- Subjects
Earth sciences ,PHYSICAL ROCK PROPERTIES (PETROGRAPHY) ,GROUND MOVEMENTS + ROCK MOVEMENTS + COLLAPSES + CAVINGS (MINING) ,TUNNELLING METHODS (TUNNELLING) ,GOTTHARD GROUP, GOTTHARD REGION (TICINO ALPS) ,PHYSIKALISCHE GESTEINSEIGENSCHAFTEN (PETROGRAPHIE) ,GEBIRGSBEWEGUNGEN + BODENSENKUNGEN + BODENAUFBRÜCHE + EINSTÜRZE (BERGBAU) ,TUNNELBAUVERFAHREN (TUNNELBAU) ,GOTTHARDGRUPPE, GOTTHARDREGION (TESSINER ALPEN) ,ddc:550 - Published
- 2003
225. Generalization of a 3-dimensional fault interaction model including tectonics, fluids, and stress transfer
- Author
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Fitzenz, Delphine Danielle and Loew, Simon
- Subjects
STRESS-STRAIN (GEOLOGIE) ,STRESS-STRAIN (GEOLOGY) ,DUCTILE SHEAR ZONE (GEOLOGY) ,PALAEOTECTONICS + NEOTECTONICS (GEOLOGY) ,PALÄOTEKTONIK + NEOTEKTONIK (GEOLOGIE) ,SAN ANDREAS FAULT, CALIFORNIA (USA) ,FAULT (GEOLOGY) ,SEISMIZITÄT (GEOPHYSIK) ,KOCAELI, PROVINZ + IZMIT, STADT (TÜRKEI) ,VERWERFUNGEN (GEOLOGIE) ,DUCTILE SHEAR ZONE (GEOLOGIE) ,FLUIDE IN ERDKRUSTENPROZESSEN (PETROGRAPHIE) ,SAN ANDREAS GRABEN, KALIFORNIEN (USA) ,SEISMICITY (GEOPHYSICS) ,FLUIDS IN CRUSTAL PROCESSES (PETROGRAPHY) ,KOCAELI, PROVINCE + IZMIT, CITY (TURKEY) ,Earth sciences ,ddc:550 - Published
- 2002
226. Ground water flow systems in the Rotondo Granite, Central Alps (Switzerland)
- Author
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Ofterdinger, Ulrich Stefan, Kinzelbach, Wolfgang, and Loew, Simon
- Subjects
Earth sciences ,PIZZO ROTONDO (TESSINER ALPEN) ,PIZZO ROTONDO (TICINO ALPS) ,GRUNDWASSERFLUSS + BRUNNENHYDRAULIK (HYDROLOGIE) ,ddc:550 ,GROUNDWATER FLOW + WELL HYDRAULICS (HYDROLOGY) - Published
- 2001
227. Structural, geomechanical and petrophysical properties of shear zones in the eastern Aar massif, Switzerland
- Author
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Laws, Susanne, Burg, Jean-Pierre, Descoeudres, François, and Loew, Simon
- Subjects
SCHERZONE (GEOLOGIE) ,SHEAR ZONES (GEOLOGY) ,PHYSICAL ROCK PROPERTIES (PETROGRAPHY) ,GOTTHARDGRUPPE, GOTTHARDREGION (TESSINER ALPEN) ,ROCK MECHANICS (CIVIL ENGINEERING) ,PHYSIKALISCHE GESTEINSEIGENSCHAFTEN (PETROGRAPHIE) ,GOTTHARD GROUP, GOTTHARD REGION (TICINO ALPS) ,AAR MASSIF (BERNESE ALPS) ,FELSMECHANIK (BAUINGENIEURWESEN) ,AARMASSIV (BERNER ALPEN) ,CD-ROM (DOKUMENTENTYP) ,CD-ROM (DOCUMENT TYPES) ,Earth sciences ,ddc:550 - Published
- 2001
228. A new strategy to map landslides with a generalized convolutional neural network.
- Author
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Prakash N, Manconi A, and Loew S
- Abstract
Rapid mapping of event landslides is crucial to identify the areas affected by damages as well as for effective disaster response. Traditionally, such maps are generated with visual interpretation of remote sensing imagery (manned/unmanned airborne systems or spaceborne sensors) and/or using pixel-based and object-based methods exploiting data-intensive machine learning algorithms. Recent works have explored the use of convolutional neural networks (CNN), a deep learning algorithm, for mapping landslides from remote sensing data. These methods follow a standard supervised learning workflow that involves training a model using a landslide inventory covering a relatively small area. The trained model is then used to predict landslides in the surrounding regions. Here, we propose a new strategy, i.e., a progressive CNN training relying on combined inventories to build a generalized model that can be applied directly to a new, unexplored area. We first prove the effectiveness of CNNs by training and validating on event landslides inventories in four regions after earthquakes and/or extreme meteorological events. Next, we use the trained CNNs to map landslides triggered by new events spread across different geographic regions. We found that CNNs trained on a combination of inventories have a better generalization performance, with a bias towards high precision and low recall scores. In our tests, the combined training model achieved the highest (Matthews correlation coefficient) MCC score of 0.69 when mapping landslides in new unseen regions. The mapping was done on images from different optical sensors, resampled to a spatial resolution of 6 m, 10 m, and 30 m. Despite a slightly reduced performance, the main advantage of combined training is to overcome the requirement of a local inventory for training a new deep learning model. This implementation can facilitate automated pipelines providing fast response for the generation of landslide maps in the post-disaster phase. In this study, the study areas were selected from seismically active zones with a high hydrological hazard distribution and vegetation coverage. Hence, future works should also include regions from less vegetated geographic locations.
- Published
- 2021
- Full Text
- View/download PDF
229. Impacts drive lunar rockfalls over billions of years.
- Author
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Bickel VT, Aaron J, Manconi A, Loew S, and Mall U
- Abstract
Past exploration missions have revealed that the lunar topography is eroded through mass wasting processes such as rockfalls and other types of landslides, similar to Earth. We have analyzed an archive of more than 2 million high-resolution images using an AI and big data-driven approach and created the first global map of 136.610 lunar rockfall events. Using this map, we show that mass wasting is primarily driven by impacts and impact-induced fracture networks. We further identify a large number of currently unknown rockfall clusters, potentially revealing regions of recent seismic activity. Our observations show that the oldest, pre-Nectarian topography still hosts rockfalls, indicating that its erosion has been active throughout the late Copernican age and likely continues today. Our findings have important implications for the estimation of the Moon's erosional state and other airless bodies as well as for the understanding of the topographic evolution of planetary surfaces in general.
- Published
- 2020
- Full Text
- View/download PDF
230. The Punatsangchhu-I dam landslide illuminated by InSAR multitemporal analyses.
- Author
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Dini B, Manconi A, Loew S, and Chophel J
- Abstract
We use multitemporal analyses based on Synthetic Aperture Radar differential interferometry (DInSAR) to study the slope adjacent to the large Punatsangchhu-I hydropower plant, a concrete gravity dam under construction in Bhutan since 2009. Several slope failures affected the site since 2013, probably as a consequence of toe undercutting of a previously unrecognised active landslide. Our results indicate that downslope displacement, likely related to the natural instability, was already visible in 2007 on various sectors of the entire valley flank. Moreover, the area with active displacements impinging on the dam site has continuously increased in size since 2007 and into 2018, even though stabilization measures have been implemented since 2013. Stabilisation measures currently only focus on a small portion of the slope, however, the unstable area is larger than previously evaluated. Highly damaged rock is present across many areas of the entire valley flank, indicating that the volumes involved may be orders of magnitude higher than the area on which stabilisation efforts have been concentrated after the 2013 failure. The results highlight that satellite-based DInSAR could be systematically used to support decision making processes in the different phases of a complex hydropower project, from the feasibility study, to the dam site selection and construction phase.
- Published
- 2020
- Full Text
- View/download PDF
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