The occurrence, mechanisms and hazards of large landslides along tablelands

Abstract

The largest terrestrial coalescent landslide areas of the Earth, spanning hundreds to thousands of square kilometres, occur along the fringes of relatively low-relief sedimentary and volcanic tablelands. However, difficulties in landslide recognition in these areas have led to underestimations of their frequency and likelihood. In this Review, we explore the global distribution, controls and dynamics of landslides occurring along tableland fringes. Landslide fringes are caused by the uninterrupted and extensive presence of weak sub-caprock lithologies below a more competent caprock. Topography, escarpment height and caprock thickness do not affect landslide size but can locally influence the type of displacement. Rotational landslides dominate most landslide fringes and will eventually lead to tableland consumption over million-year timescales. Some tableland rims can generate catastrophic long-runout rock avalanches or earthflows, which might in turn trigger tsunamis, river avulsion or outburst floods. Tablelands can also fail by slow (centimetre per year) landslide movements sufficient to cause damage to infrastructure. These hazards are increasing especially in high-latitude tablelands owing to cryosphere degradation, as observed in Western Greenland. A more detailed global inventory of landslide fringe activity is urgently needed to better quantify these potential hazards. The fringes of extensive flat-topped sedimentary or volcanic plateaus, called tablelands, host the largest coalescent landslide areas of the Earth. This Review highlights the factors contributing to extensive landslide fringes and emphasizes how climate change and cryosphere degradation could increase their hazard potential.