UNDERSTANDING LONG-TERM SLOPE DEFORMATION FOR STABILITY ASSESSMENT OF ROCK SLOPES: THE CASE OF THE OPPSTADHORNET ROCKSLIDE, NORWAY — IJEGE
 
 
You are here: Focus and scope Issues from 2005 to 2018 International Conference on Vajont 1963-2013 / Proceedings - Thoughts and analyses after 50 years since the catastrophic landslide Topic 2 - Predicting large landslide phenomena UNDERSTANDING LONG-TERM SLOPE DEFORMATION FOR STABILITY ASSESSMENT OF ROCK SLOPES: THE CASE OF THE OPPSTADHORNET ROCKSLIDE, NORWAY
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UNDERSTANDING LONG-TERM SLOPE DEFORMATION FOR STABILITY ASSESSMENT OF ROCK SLOPES: THE CASE OF THE OPPSTADHORNET ROCKSLIDE, NORWAY



Abstract:
The Oppstadhornet rockslide is a 10 Mm3 slide that occurs on the island of Otrøya in westernmost Norway. Terrestrial cosmogenic nuclide dating indicates that the Oppstadhornet rockslide became active ca. 16.6-14.2 kyrs ago when the retreat of the Scandinavian ice sheet exposed the island from the continental ice cover. Sliding along the main sliding surface was active during the late Pleistocene and Holocene. Our data suggest that the paleo-slip rate in the Late Pleistocene was slightly faster than in the Holocene however large uncertainty margins ask for care with this interpretation. Present day displacement rates of ca. 2 mm/year measured with differential Global Navigation Satellite Systems are similar to the paleo-slip rates, however they vary over the entire rockslide body and at several locations after 10 years we could not yet measure any significant displacement. The long-term activity of this rockslide suggests that - in contrast to dynamic stability models - moderate earthquake shaking with a recurrence time of 475 years will not cause the Oppstadhornet rock slope to fail.

Authors:
Reginald L. Hermanns - Geological Survey of Norway (NGU) - Trondheim, Norway
Thierry Oppikofer - Geological Survey of Norway (NGU) - Trondheim, Norway
Halgeir Dahle - Norwegian Road Authorities, Norway
Trond Eiken - University of Oslo - Oslo, Norway
Susan Ivy-Ochs - ETH Zurich- Zurich, Switzerland
Lars H. Blikra - Åknes Tafjord beredskapsenteret IKS, Norway
Keywords
long-term behavior of rockslides, terrestrial cosmogenic nuclide dating, differential Global Navigation Satellite System, paleo-slip rate, displacement rate, seismic triggering
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