Seismic investigation of submarine permafrost and permafrost-associated gas hydrates in the southern Canadian Beaufort Sea

Submarine permafrost is largely unexplored with fundamental knowledge gaps regarding its extent, thickness, degradation rates, carbon pool and the stability of permafrost-associated gas hydrates. Most of the submarine permafrost, found beneath shallow Arctic shelves in the Northern Hemisphere is relict permafrost formed during glacial and low sea level periods in the last ∼ 1 million years. With the end of the last glaciation and the subsequent sea level rise, the Arctic continental shelves were inundated, resulting in a change from very cold air temperatures to today’s warmer bottom waters, causing the submarine permafrost to thaw. The relict permafrost is still responding to this thermal change and continues to thaw. Permafrost is an essential climate variable because its degradation can lead to substantial greenhouse gas emissions. Permafrost degradation is also a potential geohazard, threatening Arctic communities and infrastructure through landslides or ground collapses. To date, Earth system models used for climate assessments and projections lack representation of key processes that affect carbon dynamics. The role of submarine permafrost is completely missing in these models due to essential knowledge gaps. In this thesis, I use marine 2D multichannel seismic data to investigate submarine permafrost and permafrost-associated gas hydrates in the southern Canadian Beaufort Sea. This work aims to improve knowledge of the lateral and vertical extent, physical conditions and potential thawing of submarine permafrost and gas hydrates on the outer continental shelf. The results imply, although permafrost has been degraded, that the stability for permafrost-associated gas hydrates seem to be largely maintained. However, thawed ice-bonding permafrost may leave sediments behind susceptible for slope failure. The retreat of ice content is essential for microbial decomposition rates and opening of migration pathways for trapped greenhouse gases.

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Zitierform:
Grob, H.J., 2025. Seismic investigation of submarine permafrost and permafrost-associated gas hydrates in the southern Canadian Beaufort Sea.
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