Characteristics of large landslides in sensitive clay in relation to susceptibility, hazard, and risk

Abstract

The clay plains of the Saint Lawrence Lowlands of eastern North America are subject to large landslides in sensitive clay. These landslides occur relatively infrequently, but can have very significant consequences. This type of risk (low frequency, high consequence) can be difficult to manage, as the return period is long enough that the most recent major event tends to be forgotten by the time the next major event occurs. This paper examines characteristics of large landslides in sensitive clay with the purpose of understanding the nature of the hazard, and this work is extended to develop a high level appreciation of risk to a network of linear infrastructure, using railways as an example. The analysis considers the characteristics of a number of large landslides documented in the literature, as well as statistical characteristics of a digital inventory of large landslides, including: surface area, debris travel distance, retrogression length, proximity to other landslides, crater shape, landslide mechanism, temporal frequency, and documented effects. A linear network with between 100 and 1000 river crossings in the sensitive clay deposits in eastern Canada is expected to suffer a major disruption once every 10 to 100 years.