A Land to Sea Perspective on Coastal Geohazards in Northeastern Canadian Fjords

Abstract

Situated at the confluence of cryosphere, land, and sea, fjords are both sensitive to, and shaped by, climate dynamics. At one end of the system, steep glacier-carved walls and glaciated headlands host active and complex geomorphic processes; at the other, deep fjord basins, also shaped by ongoing submarine activity, preserve marine sediment and bedforms that archive postglacial landscape evolution. Under current climate trends, deglaciation and permafrost degradation are increasing the frequency and magnitude of mass movements in fjord environments and heightening risks to public safety. These geohazards include rock avalanches, glacial lake outburst floods, submarine landslides, and turbidity currents—some of which can generate destructive displacement waves, posing risk to marine infrastructure and coastal communities. However, the prevalence, frequency, and magnitude of these events in eastern Canadian fjords and the processes that control them remain poorly understood. To address the knowledge gap, this thesis integrates marine and terrestrial records from eastern Canadian fjords to investigate the timing, drivers, and mechanisms of these processes in the context of a changing climate. Three projects presented here investigate distinct processes in fjords —catastrophic rock avalanches, catchment-scale sediment flux, and progressive large-scale slope deformation—that collectively highlight the influence of cryospheric dynamics and climate variability on geohazard timing, frequency, and magnitude. The first project investigates the apparent scarcity of preserved rock avalanche deposits in northeastern Baffin Island, identifies key preparatory factors and environmental conditions that influence the timing and preservation of large slope failures in high-latitude fjord terrain, and provides a novel conceptual model that predicts increase in rock avalanche activity with increased permafrost degradation. The second project explores how ice margin processes and proglacial lake formation during deglaciation shape sediment transport and submarine deposition in the fjord head environment, revealing shifts in sedimentation style and geohazard potential linked to climate-driven ice margin dynamics. The third study focuses on the development of a deep-seated gravitational slope deformation in western Newfoundland, suggesting that glacial unloading played a critical role in its initiation and postglacial evolution, as constrained by structural mapping and terrestrial cosmogenic nuclide exposure dating. Together, these studies inform how deglaciation and climate variability shape high-latitude fjord landscapes and highlight evolving hazard potential in regions undergoing rapid environmental change.