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Landslides (2008) 5:213226DOI 10.1007/s10346-008-0114-7 Received: 18 April 2007 Accepted: 17 November 2007 Published online: 23 January 2008 Springer-Verlag 2008
A. P. Dykes . J. Warburton
Characteristics of the Shetland Islands (UK) peat slides of 19 September 2003
Abstract An extreme rainfall event over the southern Shetland Islands in northern Scotland, UK, on 19 September 2003, triggered at least 20 significant peat slides and at least 15 smaller landslides of varying types. The peat slides were examined and surveyed to characterise and explain the distinctive morphological features that were produced. The failures varied in size from 0.4 to 7.3 ha (2,300 to 59,000 m3 displaced volumes of peat) and involved blanket peat up to 3 m deep and slope gradients as low as 4. Almost all of the failure surfaces were located at the peatmineral interface. The morphological features included large areas (up to0.5 ha) of intact peat that moved without breaking up, linear compression and thrust features and unusual occurrences of mineral debris. These features suggest peat of high tensile strength throughout its depth and the generation of high and sometimes artesian water pressures at the base of the peat during the event. However, the variations between peat slides highlight some of the difficulties of trying to assess the susceptibility of blanket peat to failure without full knowledge of the local peat geotechnical properties and structural features within the peat mass.
Keywords Peat slides . Blanket peat . Shetland Islands .
Landslide morphology
IntroductionMass movements in peat deposits are relatively uncommon, even in the British Isles where around 80% of all the worlds recorded peat failures have occurred (Dykes and Kirk 2006; Evans and Warburton 2007). However, in 2003, several peat failure events occurred that brought this type of phenomenon to public attention because the impacts were severe enough to command widespread media interest in the UK and Ireland (Table 1). These events consisted both of multiple rainfall-triggered slides of peat (or peaty soil)-covered slopes and head-loaded peat flows caused by engineering activities. The aim of this paper is to present details of the Shetland Island peat slides of 19 September 2003 and to highlight distinctive features not seen, to the same degree, in peat failures elsewhere. The only similar published examples also...