Msc Students 2019-2020
Moira Arnet
Hydro-biogeochemical characterization of the Bedretto Underground Laboratory for Geoenergies (BULG)
Our knowledge on the residence times and compartmentalization of fluids in the crust remains poorly constrained, despite a general understanding that flow tends to be channeled through preferential pathways. In other words, we still know very little about how deep fluids stored in fractures located a few meters away from each other can be different in terms origin, composition, temperature and biomass. The BULG, short for Bedretto Underground Laboratory for Geonergies, is a new rock laboratory developed as a testbed for research on geoenergies (Figure 1). Deep-seated up to 2 km below the surface, this laboratory gives us the opportunity to investigate hydro-biogeochemical processes in the upper crust at an unprecedented level.
This Master’s thesis, structured around field and bio-geochemical analyses in our laboratory facilities at ETH, aims to provide the first baseline characterization of the BULG in terms of deep fluid geochemistry and microbiology. This thesis will have a strong field component, with likely several surveys planned to collect water samples from tunnels and boreholes, followed by laboratory analyses at ETH. The expected results will provide insights on the spatial distribution of deep fluids and their bio-geochemical properties in the crust and also help interpreting the main field experiments planned at the BULG.
Supervisors: Bernard Brixel, Prof. Cara Magnabosco, Dr. Nima Gholizadeh
Michael Berta
A laboratory study to observe fracture propagation under controlled permafrost conditions
Observing the mechanisms of freezing-thawing cycles and water uptake in rock cracks is important in order to understand the process of fracture propagation in Alpine environments. Crack propagation can be enhanced due to forces caused by the expansion of ice while freezing. This increase in speed of the disintegration of rocks can lead to failure in otherwise unforeseen circumstances. For the prediction of rock falls for example every bit of new knowledge concerning this topic is of great value. This thesis will take an experimental approach on a laboratory scale to reproduce and study the effects of ice forming and moving in cracks due to temperature changes.
Combining investigations of frozen specimens loaded in three-point-bending configurations with temporal observations of water and ice migration on specimens housed in a purpose-built freezing box, we will investigate the processes that allow water to migrate through frozen rock to existing fractures, and the effect of permafrost melt on the initiation of cracking processes in granite bedrock.
Supervisors: Dr. Kerry Leith, Ying Li
Anja Bieler
Estimating the thickness and volume of landslides by relying on surface deformation data
Ground deformation is measured with different techniques at unstable slopes, including in-situ based and remote sensing instruments. However, surface data is not sufficient to constrain the volumes of the mobilized mass, which is an important parameter for landslide hazard assessments. In order to identify the depth of a landslide process, direct site investigations such as (i) drilling deep boreholes and/or (ii) using geophysical methods can be applied. In case (i), logistics as well as budget issues hinder the realization of a number of investigation points suitable. In case (ii) spatial and temporal resolution are intrinsically limited, and thus may provide incomplete results difficult to interpret. Recently, several authors have proposed the possibility to use surface deformation data only to extract information on thickness and basal geometry of landslides (Aryal et al., 2015; Booth et al., 2013; Delbridge et al., 2016; Nikolaeva et al., 2014). These approaches are applied to different types of landslides, and assuming different boundary conditions, mechanical properties, and/or rheologies of the moving mass. The main goal of this thesis project is to investigate the different modelling approaches proposed, and to understand their potential application in a more general framework.
Supervisors: Dr. Jordan Aaron and Dr. Andrea Manconi
Nora Bühler
Does climate change influence the frequency of large rock slope failures?
A large number of scientific contributions (e.g. BAFU 2017, Speicher 2017, Phillips et al. 2017, Ravanel et al. 2017, Haque et al. 2016) have suggested that many recent rock slope failures in the European Alps have been triggered by climate warming. For example, Huggel et al. 2012 and Fischer et al. 2012 could show that rock fall frequencies above 2000 masl increased significantly since 1990 at regional (Swiss Alps and adjacent areas) and local (Mont Blanc) scale, based on 52 events larger than 1000 m3 (PERMOS data base) covering the period 1900-2010. This increase in frequency could be correlated with a significant departure of mean annual temperature from the 1960–1990 average for a dataset describing conditions in Switzerland. Paranunzio et al. 2016 systematically studied the climatic conditions and anomalies occurring before 41 rock fall events in the Italian Alps with volumes of several hundred to several million m3. They show that positive and negative temperature anomalies triggered the majority of analysed rock fall events in a complex manner, and that melting of permafrost is clearly not the only rock fall trigger.
However, there have been no studies which investigated systematically changes in the frequency of rock fall events based on complete inventories covering a large range of rock fall volumes. To fill this gap, we have generated a new database for rapid rock slope failures in the Swiss Alps covering events larger than 100’000 m3 (Bühler 2019). This catalogue covers the period between 1700 and 2019 and includes 86 events with reliably estimated volume, date and location of occurrence, and pre-disposing factors (such as slope orientation, permafrost occurrence and geological setting). Volume-cumulative frequency plots of the events demonstrate completeness of the catalogue for all size classes, and significant changes in the ratios between large and small events through time.
In this second thesis related to this topic we will try to enlarge this database with events from the Italian and French Alps. In addition, we will try to physically explain the volume dependence of climate sensitivity through an analysis of the depth and permafrost conditions of selected events from our data base.
Supervisors: Prof. Simon Löw, Dr. Jordan Aaron
Pascale Carlen
Analogue Modelling of Large Landslides
Landslides are a natural hazard that kill about 4,000 people every year and cause billions of dollars in damage worldwide. New techniques to understand landslide mechanisms and quantify landslide risk can reduce losses from landslides. In many large landslides in rock and soil, two key questions must be answered to assess risk: 1) what is the volume of material involved in the failure? 2) What is the subsurface mechanism governing movement? This project addresses both of these questions using an analogue modelling approach.
Large landslides have distinctive 3D surface displacement fields, which are a function of their volume and movement mechanism. Several authors have recently proposed methods to use this field data to estimate the volume and movement mechanisms of large moving landslides, based on inverting subsurface characteristics from surface displacements. Validation of these methods is difficult, due to a lack of subsurface data. The goal of this project is to run analogue laboratory experiments to understand the relationship between surface and subsurface displacements.
Supervisors: Dr. Jordan Aaron
Nadir Dazzi
Understanding groundwater flow in unsaturated fractured zones of alpine mountains: from field observation to numerical simulation
Groundwater flow through thick unsaturated fractured zones (above the water table) is often dominated by high-permeability discontinuities that form the preferential pathways and accommodate “fast” flow, whereas the low-permeability rock matrix that only permit “slow” flow plays a minor role. For example, the water resulting from precipitation and/or snowmelt at Aletsch (Valais, Swiss Alps) tends to infiltrate into the subsurface and flow through conductive fractures (e.g. joints and faults). The objective of this MSc thesis is to develop a combined observational and numerical study to advance the state-of-the-art in understanding in this problem. The student will be integrated in a long-term interdisciplinary monitoring project in an alpine environment, i.e. Aletsch glacier, Switzerland. The methods to be used in this project will include both field work and numerical modelling. Advances in understanding this problem has important implications for many geo-engineering problems related to the Earth’s surface/near-surface, such as rock slope stability, tunnel excavation, nuclear waste disposal and groundwater management.
Supervisors: Dr. Qinghua Lei, Nicolas Kyochi Oestreicher, Marc Hugentobler, Prof. Simon Löw
Niels Goedhart
Understanding Lunar Landslides Using Deep Learning and Numerical Modelling
Extremely-rapid, flowlike landslides can impact people and property far from their source. These types of landslides have been studied for over 100 years, however a consensus regarding the mechanisms that govern their motion has yet to emerge. Understanding the movement mechanisms is crucial for accurate prediction and management of the hazard posed by these catastrophic events. The recent availability of high quality imagery of the Moon has revealed numerous extraterrestrial flowlike landslides. These flows have the potential to reveal previously unknown features of catastrophic landslides, and may reveal information about dynamic erosion processes on the moon, and the rate of erosion of lunar craters. In this project, the student will use recent advances in numerical modelling and deep learning to map and analyse flowlike landslides on the moon. This will provide information about the mechanics of flowlike landslides, as well as the surface evolution and erosional state of the lunar surface.
Supervisors: Dr. Jordan Aaron, Prof. Simon Löw, Valentin Bickel
Tobias Halter
Searching for the rupture plane of the unstable Guobu rock slope adjacent to the Laxiwa Hydropower Station, China
The Laxiwa Hydropower Station in China witnessed its nearby right-bank Guobu slope (700 high, 1000 m wide and only 500 m away from the dam) displacing horizontally more than 7 m as well as significant signs of instability (e.g. tension cracks and rockfalls) soon after the reservoir impoundment in 2009. This unstable granitic rock slope remains active many years after the impoundment and has accumulatively displaced up to ~40 m, imperilling the hydropower plant and downstream residents. If the slope fails catastrophically at some point in the future, the landslide into the reservoir may generate significant impulsive waves overtopping the Laxiwa Dam and flooding nearby towns/villages. Thus, it is crucial to predict the future evolution of this unstable rock slope. Extensive drilling efforts have been conducted at the Guobu slope attempting to detect its potential rupture plane, but with no success. A strong debate still remains on whether such a rupture plane exists underneath the unstable rock mass volume, and if so, where is it? The objective of this MSc thesis is to study the geological settings and kinematic behaviour of the Guobu rock slope and search for its potential rupture plane. The student will be integrated in an international and interdisciplinary project and collaborate with many other researchers in the host/partner institutions and relevant hydropower companies/institutes.
Supervisors: Dr. Qinghua Lei, Dr. Andrea Manconi, Prof. Simon Löw, Prof. Yaoru Liu
Julian Hemmi
Runout Analysis of Three Rock Avalanches in the Illgraben Catchment
The Illgraben debris flow torrent, located in the Rhone-Valley in central Switzerland, is the site of a unique facility that monitors extremely-rapid, flowlike landslides. In addition to numerous debris flows, two rock avalanche deposits have been identified, mapped and dated. Monitoring of the slopes in the upper part of the catchment has revealed the possibility of future rock avalanche activity in the torrent. In this project, the student will integrate field data and numerical modelling in order to make probabilistic predictions of the potential impact area and velocity of a potential future rock avalanche. The two past events mapped in the torrent will be used to calibrate a numerical model, which will then be used for prediction. Empirical runout analysis will also be performed, and the results compared to numerical predictions. Depending on the interests of the student, field work may be undertaken to better constrain the deposit distribution of the previous rock avalanches in the catchment.
Supervisors: Dr. Jordan Aaron and Dr. Brian McArdell (Geologist, Swiss Federal Institute WSL)
Patricia Hug
Holocene rock avalanches and evolution of the polygenic Frébouge cone, Val Ferret Mont Blanc Massif
The Mont Blanc Massif presents a striking, glacially scoured high-relief topography; when combined with steep slopes and fractured rock walls, high rates of gravitational movements, such as rock avalanches, are inevitable. The focus of this MSc thesis is on deciphering the evolution of the Frébouge polygenic cone. To do this, several landscape reconstruction tools will be combined. Much of the build-up of the cone has been through debris flows that remobilize the forefield sediment of the nearby Frébouge glacier and by glacial sediment during glacier advance phases. This is augmented by debris delivered by both ice and snow avalanches, as well as rockfall. Blocky deposits on the distal part of the cone indicate rock avalanche events. The timing and source for the blocky, rock avalanche deposits have yet to be established. Cosmogenic nuclide dating will be used to establish their age. By combining information on boulder and bedrock lithologies (all granitic) in the steep walls, insights into the source area may be gleaned. The student will use Dan3D runout modelling to compare candidate release areas with the distribution of the rock avalanche deposits at the cone toe and to model the dynamics of the rock avalanche, which must have fallen and partly travelled on the glacier. Furthermore, temporal constraints on build-up of the debris-flow deposits may be established through trenching. Detailed geomorphological field mapping will help in constructing a relative age sequence supplemented by interpretation of imagery gained with an unmanned aerial vehicle. The data obtained in this study, will allow reconstruction of the timing of cone build-up, and allow estimation of the contribution of the several geomorphological processes to cone volume. Insight into the evolution of glacier-influenced polygenic cones in steep mountain environments aids our understanding of these processes, including their interaction and the hazards that they pose to communities in steep mountain valleys.
Supervisors: PD Dr. Naki Akçar (University of Bern, Lehrauftrag at ERDW ETH),Prof. Susan Ivy-Ochs, Dr. Jordan Aaron, Prof. Philip Deline (Savoie University)
Simran Johal
How fracture topology influences fluid flow: joint field and numerical study
In tight rocks, fluid flow is confined to a network of interconnected fractures embedded in impermeable rock masses. Characterizing these fractures and understanding how they collectively interact to create flow pathways is an important task in many civil, rock and hydraulic engineering applications. However, despite significant computational advances, practitioners and researchers still struggle to describe these fracture systems realistically due to the lack of high-resolution data.
This Master’s thesis, structured around both field and desktop work, aims to help bridge the gap between data and models by simulating geologically-sound fluid flow scenarios on discrete fracture networks (DFNs). To this end, we will start by characterizing real, natural fracture systems based on state-of-the-art field mapping techniques tailored to surface outcrops, tunnel exposures and borehole data obtained at or in the vicinity of the Grimsel Rock Laboratory, an underground (0.5 km depth) site in the Central Aar Massif dedicated to research in crystalline rock. We will then build DFNs to simulate fluid flow, track how pressure diffuses and compare our results to high-resolution cross-hole hydraulic datasets. If time allows, we will also test our results on fracture patterns from the Bedretto Rock Laboratory, where new fault-stimulation experiments are currently underway.
Supervisors: Bernard Brixel, Dr. Qinghua Lei, Dr. Martin Ziegler
Moritz Lesche
Large rock slope deformation triggered by reservoir impoundment: A case study of the Guobu slope at the Laxiwa Hydropower Station, China
The Laxiwa Hydropower Station in China witnessed its nearby right-bank Guobu slope (700 high, 1000 m wide and only 500 m away from the dam) displacing horizontally more than 7 m as well as significant signs of instability (e.g. tension cracks and rockfalls) soon after the reservoir impoundment in 2009. This unstable granitic rock slope (with an estimated volume >5 Mm3 and prone to flexural toppling) remains active many years after the impoundment and has accumulatively displaced up to ~40 m, imperilling the hydropower plant and downstream residents. The objective of this MSc thesis is to conduct a combined field investigation and numerical modelling to unravel the large deformational behaviour of the Guobu rock slope at the Laxiwa Hydropower Station due to the reservoir impoundment. The research in this MSc thesis involves both field work and numerical modelling. The student will be integrated in an international and interdisciplinary project and collaborate with many other researchers in the host/partner institutions and relevant hydropower companies/institutes.
Supervisors: Dr. Qinghua Lei, Prof. Simon Löw, Prof. Yaoru Liu
Zhasmin Mussina
Tamins rock avalanche dating and runout modelling MSc project
This project is aimed at combing several methods, particularly cosmogenic nuclide exposure dating and DAN3D runout modelling, to understand the timing and dynamics of the Tamins rockslide. In the region of the confluence of the Hinterrhein and Vorderrhein Rivers, deposits related to both the Flims and the Tamins landslides as well as marked terraces interfere to form a complex and enigmatic landscape. Although huge on its own (1-2 km3), the Tamins deposits have received notably less study than the nearby Flims deposits (12 km3), because of the latter’s dominance of the landscape. The Tamins deposits comprise huge semi-intact bedrock-like massifs (Rascheu, Cartschitscha, Ils Aults, Crest’Aulta) that must have moved en bloc down from the Kunkelspass niche. Modelling with Dan3D-flex which allows the moving mass to remain semi-intact during flow may help to understand the origin of these blocks. Although over the last century and a half the area has been studied by numerous workers, fundamental questions remain about the relationship of the two landslides and the sequence of events. The age of the Tamins rockslide is one of the key missing pieces in the puzzle. The study of colossal landslides as for example at Flims and Tamins provides a glimpse into processes that are not possible to view at present as no events of such magnitude have occurred during historical times. Insights into past and future failures can be gained.
Supervisors: Prof. Susan Ivy-Ochs, Dr. Jordan Aaron, Prof. Adrian Pfiffner, Dr. Andrea Wolter
Lukas Röthlisberger
Differentiating natural and human-induced earthwquakes in Switzerland using machine learning
Lilith Schacherer
Preconditioning and runout of the Eibsee and Ehrwald rock avalanches following the Last Glacial Maximum
The impact of glacier retreat on rock slope instability since the Last Glacial Maximum is the subject of ongoing debate. Rock slope activity since ice retreat is typically attributed to increased kinematic freedom as a result of erosion during glaciation, debuttressing of valley walls which may have been supported by glacier ice, specific patterns of Holocene seismicity, or an exposure of rock slopes to increased chemical and biological weathering during the present interglacial. Here, rather than looking for a particular driver or trigger for rock slope instability, we will evaluate the potential for rock mass degradation in response to micro-cracking in critically stressed near-surface bedrock (0 – 2 km depth) in the region of the Eibsee and Ehrwald rock avalanches to the north and west of the Zugspitze peak (DE). Rather than focusing on a specific driver, this allows us to identify regions in which fracture development is likely to be ongoing, and slope stability is therefore decreasing with time.
Together with new sedimentological data gathered by the Technical University of Munich, we will evaluate the processes leading up to the rock avalanche using RS2 software, and model the dynamic runout of the rock avalanche using DAN 3D. Depending on results, additional dating of landslide deposits using cosmogenic nuclides may be used to better constrain the timing of processes leading up to the events.
Supervisors: Dr. Kerry Leith, Dr. Jordan Aaron, Prof. Susan Ivy-Ochs, Prof. Michael Krautblatter (TU Munich)
Haonan Yang
Progressive rock slope failure: a power law or dragon king?
Rock slope failure often shows a progressive manner such that numerous small and intermediate-scale instability phenomena appear before the occurrence of a large-scale catastrophic event. For example, on 15th May 2012, a massive rockslide carrying a large volume (~210,000 m3) of debris occurred near the village of Preonzo in the Swiss Alps. Field monitoring and observational data indicated that, before this avalanche, the slope continuously exhibited creeping behaviour over a long period of time as well as many instability features such as smaller-sized rockslides and countless rockfalls. During the slope destabilisation process, it exhibited episodic displacement rate accelerations in coincidence with rainfall events, suggesting that the slope was close to the critical point and were thus very sensitive to external perturbations. It is well known that a system close to the critical point is usually characterised by scale-invariant properties and self-similar behaviours. These properties/processes are often mathematically described by fractal or power-law statistics with no characteristic scale, indicating that phenomena at different scales are governed by the same mechanism and thus no distinct precursors may be predicted for large events. However, as the system approaches catastrophic failure, the nonlinear interactions among its constitutes at different scales become very significant and the positive feedbacks may lead to large-scale coherent collective behaviours dominating the entire system, e.g. the rupture plane formation. Such crises and extremes, called “dragon-kings”, tend to live beyond power-law, rendering a possibility of predicting their appearance. The objective of this MSc thesis is to understand the mechanisms that govern progressive rock slope failure leading to the emergence of power-law and dragon-king statistics. Field monitoring data such displacement variations will be analysed to examine the existence of power-laws and dragon-kings and their potential correlation with slope predisposition properties (e.g. fracture patterns) and external drivers (e.g. rainfall events).
Supervisors: Dr. Qinghua Lei, Prof. Simon Löw, and Prof. Didier Sornette