Mass movements in peat: A formal classification scheme

Published accounts of peat mass movements throughout the last 500 years reveal common characteristics among the failures; however, there has been no consistency in the terminology used to describe them. Given the apparently increasing frequency of peat failures in the British Isles and the possibility of more peat failures elsewhere in the world as a consequence of climate change, there is a need for a specific classification scheme. This paper proposes a scheme that uses clearly defined terms that can be readily applied and reliably used to understand and assess future hazards from peat mass movements. The paper begins with a general definition of what should constitute a ‘peat failure’, then presents a precisely defined classification scheme for peat landslides (i.e. excluding creep), using type of peat deposit and failure morphology as the key criteria. The new scheme for peat failures is discussed in the context of existing landslide classification systems. Definitions are provided for bog bursts (flow failure of raised bogs), bogflows (flow failure of blanket bogs), bog slides (shear failure and sliding of blanket bogs), peat slides (shear failure at peat–mineral interface in blanket bogs), peaty-debris slides (shear failure within mineral substrate beneath blanket bogs) and peat flows (natural failures of other types of peat deposits including flow failure caused by head-loading). Some practical problems of classifying peat failures are discussed.