Surface Deformation and Slope Instabilities in Deglaciating Mountain Environments

This exciting project aims to improve our understanding of the impact of glacial retreat on slope stability and surface and sub-surface deformation in high mountain areas. The project will use the latest satellite data and technologies to measure present-day and past deformation around glacial valleys that have been recently exposed due to retreat. The study has the potential to focus on areas in the High Himalayas, the Pamirs, the Southern Alps of New Zealand, Alaska, Andes and/or Patagonia depending on the candidate’s interests and the progression of the project, and there will be opportunities for fieldwork in some of these destinations if desired.

Background
This project will explore a range of space-based synthetic aperture radar (SAR, e.g. Sentinel-1) and optical (e.g. Planet) imagery (Elliott et al, 2016) to develop quantitative methodologies for assessing surface deformation around retreating glaciers in high mountain areas (Luckman et al., 2007). Characterising this activity is important for assessing the location and rates of loss of ice mass in these areas, as well as for determining changes in the stability of surrounding slopes  that may lead to mass failure and, where lakes exist, flooding (Quincey et al., 2005). Attention will be focussed on both glacierised and recently deglacierised terrain, as well as around the glacier margins where periglacial processes are active. On-glacier, measurements of surface deformation from Interferometric Synthetic Aperture Radar (InSAR) may indicate seasonal variations in flow, and/or rates of surface lowering. Surface velocity fields derived for surging glaciers may yield insights into their trigger mechanisms, the processes controlling surge evolution, and/or provide early indication of a developing event. Off-glacier, time-series analysis of slope stability (Dini et al., 2019) may identify the onset or acceleration of failures at the margins and test ideas around the loss of buttressing versus the uphill migration of permafrost as dominant drivers of mass movement events.

Further ideas could explore the potential to examine the stability of moraines at lake margins formed at the toes of retreating glaciers, as these constraints are important for determining the potential susceptibility to failure from shaking events such as earthquakes. It may also be possible to derive horizontal and/or vertical displacements over rock glaciers to provide some novel insight into their poorly-understood dynamics.

Initially the project will focus on the region of the high Himalayas of Central Asia, building on previous studies from within the project supervisory groups (e.g. Quincey et al., 2009 and King et al., 2017) using both SAR and optical imagery as well as digital elevation models (DEMs). Further deglaciating and deformation prone areas will also be targeted such as in the Southern Alps of New Zealand, the Patagonian region of southern Chile/Argentina, the Andes, Alaska or the Pamirs of Central Asia. All of these high mountain areas are becoming increasingly dynamic as the environment warms and the project will seek to quantify the changes that are evident over annual to decadal timescales.

The Hispar Glacier of the Karakorum as viewed in remote sensing images: (left) Sentinel-1 InSAR Phase and Amplitude image and (right) Sentinel-2 Multispectral RGB image. These datasets can provide complementary information on glacial valley behaviour.

Objectives
In this project, the student will apply the latest remote sensing techniques in measuring surface deformation, landsliding and glacial retreat in mountainous regions. The project will have the following specific objectives:

  1. To use satellite-based radar (InSAR) around retreating glaciers in high mountain areas (one or more of Himalayas/Southern Alps NZ/S. America) to characterise surface and subsurface changes associated with melting ice and surface elevation changes. Images will be used to map out and identify the extent of glaciers within SAR images and constrain the location and rates of deformation in time series analysis of InSAR data. Larger surface displacements will be quantified using feature tracking techniques on both SAR and optical images.
  2. To quantify and characterise the initiation and acceleration of landslide failures at the valley margins as the ice retreats through time, using high resolution InSAR data on the slopes. These data will be used to test ideas of the driving mechanisms of slope instability.
  3. To advance the techniques and datasets used to constrain rates of ice mass loss using the analysis of optical data, SAR amplitude and optical stereo-derived DEM differences for estimating extents and volumes of ice change at spatial and temporal resolutions that have not previously been possible.

The balance between these components will vary depending on the specific interests of the student.

Potential for Impact
This project is timely as the impact of climate change is changing the dynamics and behaviour of glaciated systems in high mountain areas. Improved knowledge of the rates of deformation and stability in these regions is urgently needed. The international scope and relevance of this work will allow presentation of the project outcomes at international conferences and the results of the work will be published in leading international journals.

Training Environment
The student will work under the supervision of Dr John Elliott, within the Tectonics group of the Institute of Geophysics & Tectonics in the School of Earth & Environment at Leeds, and by Dr Duncan Quincey in the River Basin Processes and Management cluster within the School of Geography. The student will be embedded in a large group of postgraduate research students and postdoctoral staff working on remote sensing and geodesy projects applied around the globe and will benefit from being part of two very active and world-leading research groups within the Faculty. There is also the potential for field-based training depending on the interests of the candidate, and for field assisting on other related projects.

The Institute of Geophysics & Tectonics also hosts the Centre for the Observation and Modelling of Earthquakes, Volcanoes and Tectonics (COMET http://comet.nerc.ac.uk/) which provides a large group of researchers engaged in surface deformation research with whom the student can interact across the themes of hazards, tectonics and volcanology. The successful PhD student will have access to a broad spectrum of training workshops put on by the Faculty that include an extensive range from scientific computing through to managing your degree, to preparing for your viva (http://www.emeskillstraining.leeds.ac.uk/). The student will also have the opportunity to engage with a wider range of scientists within COMET at a number of other UK institutions who have a broad interest in problems of active tectonics and earthquakes.

Student profile
The student should have a strong interest in remote sensing, surface deformation problems, and a strong background in a quantitative science (earth sciences, physical geography, geophysics, geology, physics, natural sciences). Ability to work within a G.I.S framework and experience of remotely sensed datasets would be useful.

References

Dini, B., S. Daout, A. Manconi & S. Loew (2019).
Classification of slope processes based on multitemporal DInSAR analyses in the Himalaya of NW Bhutan,  Remote Sensing of Environment, 233, p.111408.

Elliott, J. R., R. J. Walters & T. J. Wright (2016).
The role of space-based observation in understanding and responding to active tectonics and earthquakes, Nature Communications, 7, doi:10.1038/ncomms13844.

King, O., Quincey, D.J., Carrivick, J.L. and Rowan, A.V., (2017).
Spatial variability in mass loss of glaciers in the Everest region, central Himalayas, between 2000 and 2015. The Cryosphere, 11(1), pp.407-426.

Luckman, A., Quincey, D. & Bevan, S., (2007).
The potential of satellite radar interferometry and feature tracking for monitoring flow rates of Himalayan glaciers. Remote sensing of Environment, 111(2-3), pp.172-181.

Quincey, D.J., Luckman, A. & Benn, D., (2009).
Quantification of Everest region glacier velocities between 1992 and 2002, using satellite radar interferometry and feature tracking. Journal of Glaciology, 55(192), pp.596-606.

Quincey, D.J., Lucas, R.M., Richardson, S.D., Glasser, N.F., Hambrey, M.J. and Reynolds, J.M. (2005).
Optical remote sensing techniques in high-mountain environments: application to glacial hazards. Progress in Physical Geography, 29(4), pp.475-505.