Abstract
Spatial distribution of paleolandslides coincides with postglacial faults (PGFs) in northern Fennoscandia, yet the timing of the seismic events and associated paleoslides is insufficiently known. We applied airborne LiDAR (Light Detection And Ranging) to record distribution of paleolandslides possibly associated with the known Suasselkä postglacial fault in Kittilä, western Finnish Lapland. Landslide-buried organic material was radiocarbon dated to bring insight if the landslides were generated by single high-magnitude (Mw>7) earthquake or if seismic activity has continued through the Holocene. We found a total of four sets of previously unrecognized paleolandslides to indicate fault-activity in the Kittilä area. The size of the landslide scarps exceeded up to 250–300m in width, up to 600m in length and 10m in the height of the back-wall. A previously unrecognized (tentatively PGF) scarp, 6m in height and in conjunction with paleolandslides, was found in granite rock west of the Kittilä village. The slide debris was similar to local tills, yet the maximum electrical conductivity (σa) anisotropy was incoherent to any of the ice-flow (morphological) stages recognized through LiDAR or known fabric-sedimentary stratigraphy. We found peat/gyttja beneath 6m of slide debris which yielded radiocarbon (14C) age of 4400±35BP (cal. 5055yrBP). Our previous finding of landslide-buried woody remnants of birch (Betula ssp.) yielded cal. 9730yrBP in Kittilä. These ages suggest that seismic activity has continued at least 5ky after deglaciation.
Published Version
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