Department of Earth Science

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Masterprosjekt - Energi

Effects of near-surface thawing of frozen surface sediments on the signatures of seismic surface waves

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Project description

The ongoing rise in temperature in the Arctic may have severe effects on huge areas of the todays permanently frozen tundra in the Northern Hemisphere. Thawing of frozen sediments will cause release of water, the soil to become unstable and possible outlets of climate gases. Seismic waves are very sensitive to the stiffness of sediments, and, thus, as frozen sediments thaw their seismic properties will alter significantly. If the seismic properties of near-surface sediments can be monitored over time, this can potentially be used to predict the heat flux into the terrestrial Arctic.

Seismic velocities in unconsolidated sediments will vary significantly with the extent of frozen water within the pore volume. Time lapse studies of surface waves in an area subjected to freezing and thawing can potentially be used to monitor vertical temperature distributions of the upper sediments. The problem is first to study the sensitivity of surface waves by seismic modelling, particularly related to observed seismic velocity variations of surface sediments in Svalbard.  Second, the problem is to adapt the seismic modelling to sediment conditions relevant for Adventdalen and compare with experimental data acquired during the spring of 2019. 

The work is to study seismic data acquired during spring and autumn of 2019 to study time lapse effects caused by various degrees of thawing of the upper sediments. Synthetic velocity models based on rock physics modelling and estimated velocity models based on inversion of real data and well data are to be used to discuss possible seismic signatures caused by various thawing rates of the upper sediments in Adventdalen at Svalbard.