Svalbard rockslide adventures- how Arctic is too Arctic?

-by Louise Vick The answer: there is no such thing as too Arctic!

From Left: Michael Fuchs (BGR), Dr Drivel (NGU), Nick Schüßler (BGR), Martina Böhme (NGU), Louise Vick (UiT), Dirk Kuhn (BGR), Andreas Grumstad (UiT), Photograher: Reginald Hermanns (NGU)

In the summer 2021 UiT was lucky enough to be involved in an unstable rock slope field campaign in Svalbard. The trip was managed by the Engineering Geology group at BGR in a project collaboration with the Geohazard and Earth Observation group at NGU. Our fearless polar expedition leaders were Dirk Kuhn from BGR and Reginald Hermanns from NGU. They, together with other team members, have published two articles from data from previous mapping campaigns as a part of this project. See Kuhn et al 2019, and Kuhn et al 2021 on the unstable slope at Forkastningsfjellet for reference.

Some of group embarking on the first day of mapping at Forkastningsfjellet. Note tilted beds of a partial rockslide collapse in the upper right side. From left: Reginald Hermanns, Dr Drivel (Tim Redfield), Martin Böhme, Louise Vick and Dirk Kuhn

Andreas and I tagged along to lend some extra eyes to the slope problems, and to see slides in a different geological environment. We weren’t dissapointed! You may or may not know that Svalbard is a sedimentary rock landscape, with a layer cake assemblage evoking images of the Grand Canyon and desertscapes in the US. These sedimentary layers are not quite horizontal- they dip ever so slightly to the south. Therefore, tracking our journey northward up Isfjorden/Billifjorden resulted in a sail through time- each step northward revealing an older layer to the assemblage.

Layercake rocks make mapping deformation interesting… displacement is easy to prove (or disprove)

Our group of 7 researchers set out from Longyearbyen on the Ocean B- a 20 m 5 cabin yacht captained and crewed by the Polish company Natango. These come highly recommended by the way- food and service was impeccable. We had plans to stop at 6 potentially unstable rock slopes along the flanks of Isfjorden and Billifjorden. In the end, we made 5 detailed stops, plus some token tourism at during the downtime at Pyramiden and Nordenskiöldbreen. The deformation of these sedimentary rock slopes is quite different to those we see in Troms. While displaced segments are clearly bounded by structures, the material itself is often intact, preserving it’s layer cake stratigraphy and enabling offset/rotation to be mapped. Several times we encountered blocks of rock which may have looked in situ from the geomorphology, and only once we tracked its lithology to cliffs 100’s of metres above could we say it was offset. However in other cases I was convinced we had an offset block as a result of deformation, but the stratigraphy showed it was in situ. In these cases, Winfried Dallman (another UiT geologist) and his lithological maps proved invaluable for checking where in the lithological hell we might be! In addition, the paleontology skills of Michael Fuchs was helpful for checking we had correctly identified the sequences against the geological maps.

Dislocated and rotated blocks of Forkastningsfjellet
Andreas standing by beds that appear tilted, but are in fact in situ and part of an isoclinal fold on Hjortfjellet.

There is also a lot of active surface processes taking place. Debris flows, frost shattered ground, gelifluction and eminent talus fan systems were ubiquitous in the mountain slopes and plateaus. These often made it difficult to interpret signs of deeper deformation. They were indicative of the process regime in Svalbard- wet cold summers and frosty snowy winters. We observed some frost heave hexagons in higher areas, within shattered talus from rockslide action.

Patterned ground from frost heavy in a graben created by deep seated deformation

Forkastningsfjellet Forkastningsfjellet is a mega rockslide near to longyearbyen. The deformation stretches across the entire elongated ridgeline of the mountain. Large blocks have slumped down towards the water, rotating backwards with a clear back-tilt of the stratigraphy (in situ material sits more or less horizontal). In 2016 a small part of of the mega slide failed, coming the rest on the beach and partially in the water.

2016 partial collapse of Forkastningsfjellet. Credit: Icepeople

Kuhn et al. 2019 related the ongoing failure of Forkastningsfjellet to continuous deformation following deglaciation of the region ~13 thousand years ago. Slow creep, potentially exacerbated by permafrost retreat known to be occurring drastically across the Arctic, led to the eventual release of the 2016 slide and potentially will lead to more failures. The sheer size of the monster (a potential failure of up to 10 Mm3) and the proximity of the mountain to civilisation means there is a risk of tsunami impact to people or *the all-important* infrastructure.

Map by Kuhn et al. 2019 of landslide blocks at Forkastningsfjellet

Fun in the Arctic

We had fun editing plans on the fly due to Polar Bears at landing sites, crashed drones, and that *tropical* Arctic summer weather blowing in. Downtime meant extra time looking at beautiful glaciers and mountains, and listening to Dr Drivel (Tim) tell us stories numbering from -12 to 97, and i quote ‘regrets are for fools‘.

Dr Drivel, for once, remaining silent in the face of nature

It was great to get back to basics with real geology field mapping (albeit with an ipad instead of a compass), and the sedimentary rocks provide a welcome break from our usual hard, old metamorphic rocks in Troms.

We even had some nice weather days! On good days the temperature is more or less like autumn fieldwork in Troms- brisk but bearable, and even pleasant at times. We are holding out hopes for an opportunity to go back! In the meantime, keep an eye on the literature 😉

The lovely curves of Hjortfjellet

Andreas enjoying lunch in the sunlight
Martina surveying her mountain

Nordenskiöldbreen (glacier)

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