Toward a process-based understanding of sediment degassing and ramifications for the mechanical stability of permafrost, Earth Materials and Processes
Abstract
About a quarter of the ice-free land area in the northern hemisphere is affected by thawing processes in perennially frozen ground called permafrost. In fact, numerous communities in Alaska and the Northwest Territories are already struggling with the practical implications of climate-induced soil destabilization, including catastrophic slope failure, road damage, enhanced erosion and house collapse. In some locations, these challenges have reduced habitability to a degree that makes relocalization of the entire community inevitable. the goal of this proposal is to contribute to our fundamental understanding of the delicate feedback between surface and subsurface processes that govern permafrost degradation and thereby the mechanical stability of the soil column. An improved understanding of the physical processes governing permafrost dissociation will advance our ability to assess the variability of future change and quantify the possibility of potentially catastrophic mechanical instabilities. An important component of the proposal is to study the processes giving rise to the large temporal and spatial variability in permafrost dissociation, because variations in permafrost stability are likely to directly translate into variations in soil stability. To achieve our goal, we link field observations, laboratory experiments and numerical modeling. For the field component, we propose to study the link between methane degassing and mechanical stability in three natural systems of increasing complexity: lakes, marine basins and subaerial permafrost. To understand observations, we integrate insights from recent laboratory experiments that shed light on the behavior of materials consisting of solid, fluid and gaseous components. We propose to complement these analog experiments with a virtual laboratory that allows us to extrapolate from an idealized laboratory setting to the natural world. We couple this granular-scale model to a regional-scale model through which we can analyze the large-scale consequences of the observed granular behavior. Using this two-tier modeling approach, we can both investigate the fundamental physics and capture the response of the system. We are particularly interested in identifying tipping points in the non-linear mechanics of degassing sediment and soil that could lead to large-scale mechanical instability. Our proposal has the potential to shed new light on the delicate feedback loops governing permafrost dissociation and could have an impact on our ability to adapt to rapid environmental change in the Arctic. The models we develop lend themselves to integration into large-scale models, to identification of testable predictions for further laboratory tests and comparison against future field data.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 01, 2019
- Source ID
- W911NF1910088
Entities
People
- Jenny Suckale
Organizations
- Army Contracting Command
- Stanford University
- United States Army