Early Holocene coastal landslides linked to land uplift in western Sweden

ABSTRACT

The recent availability of high-resolution digital elevation data has revealed numerous large landslide scars in glaciomarine deposits in Western Sweden. In order to determine the timing and cause of six such landslides, geomorphic and stratigraphic investigations were undertaken. Based on cross-cutting relationships between the landslide scarps, raised shorelines, and other wave-washed deposits, the geomorphology indicates that the slides occurred along early Holocene coastlines. Parts of each slide occurred below and above sea level. Stratigraphic investigations at the six landslides reveal the presence of glaciomarine fine sand below glaciomarine clay and the presence of confined aquifers beneath the landslides. Given this stratigraphy and the geomorphic link to the coastlines, it is interpreted that the emergence of the groundwater recharge zones above sea level allowed pore pressure to build within the aquifers and led to slope failures. It is suggested that the mechanism linking falling isostatic sea level to these near-shore/coastal landslides may also apply to continental slope landslides during periods of falling eustatic sea level.

KEYWORDS:

• Landslide
• Sweden
• sea level

Acknowledgements

The authors wish to acknowledge the mapping efforts of H. Mikko that initially identified many of these landslides. G. Peterson and L. Rodhe provided comments and discussion on earlier drafts of this manuscript, and D. Long and an anonymous reviewer provided constructive reviews. Drilling and geotechnical data collection were carried out by Bohusgeo AB.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

Colby A. Smith is an American glacial geologist currently working for the division of Geohazards and Climate at the Geological Survey of Sweden.

Olof Larsson is a Quaternary geologist at the Geological Survey of Sweden branch office in Gothenburg. He works in the division of Marine Environment and Planning.

Mats Engdahl is a Quaternary geologist at the Geological Survey of Sweden branch office in Gothenburg. He works with Quaternary deposit and landslide mapping in western Sweden. Nowadays, he also works with geology in urban planning.

ORCID

Colby A. Smith http://orcid.org/0000-0002-7335-6281