Submarine mega-slides from the Norwegian Continental margin and their relationship to periods of climatic change

• Main Author: Watts, Camilla, Jane
• Format: Thesis
• Language: English
• Published: 2019
• Subjects: Lofoten; Storegga; Tampen; North Atlantic
• Online Access: https://eprints.soton.ac.uk/432098/; https://eprints.soton.ac.uk/432098/1/Watts_Camilla_PhS_Thesis_June_2019.pdf

Submarine landslides can be orders of magnitude larger than their terrestrial counterparts. The largest of these submarine slides have the potential to generate devastating pan-oceanic tsunamis. For example, the Storegga Slide that occurred on the Norwegian Margin around 8,200 years ago, contained over 3,000 km3 of material. This slide produced a tsunami that has been detected on coastlines across the North Atlantic, reaching 5 m above sea level across much of Scotland. This landslide was the most recent in a series of mega-slides from the same location, during the last 2.74 Ma. The triggering of these slides has been linked to major deglaciations of the Quaternary period, yet only the 8.2 ka Storegga Slide has been accurately dated. Within the context of modern rates of climate change, this link between large slides and glacial cycles requires further evaluation. This thesis seeks to understand the timing of these mega-slides, by using a sediment core that captured the distal deposit of the last two slides from the Storegga Slide Complex. It is shown that the penultimate (Tampen) slide occurred at 55.9 ± 4 ka BP, rather than at ~130 ka BP as previously thought. The Tampen Slide is thus much younger than previously thought, and occurred during early period of MIS 3, following a significant deglaciation at the end of MIS 4. We therefore show that the last two mega-slides (Tampen and Storegga Slides) both occurred a few thousand years after periods of significant warming. By showing that the Tampen Slide is much younger than previously thought, this work suggests that mega-slide recurrence times may be shorter than previously thought. Finally, a new slide deposit from the Lofoten Contourite Drift is dated. We show that this slide occurred ~5,500 year ago during a period of relative climate stability, suggesting that slide occurrence is not always linked to climate cycles. This work highlights our incomplete understanding of submarine slide preconditioning and triggering.