Human settlement pressure drives slow-moving landslide exposure

Abstract

The rapidly growing population in many mountain regions is pressuring expansion onto steeper slopes, increasingly exposing people and their assets to slow-moving landslides [1, 2, 3, 4]. These moving hillslopes can inflict damage to buildings and infrastructure [5, 6], accelerate with urban alterations [7, 8], and catastrophically fail with climatic and weather extremes [9,10,11]. Cities in mountains especially face growing pressure from rising and migrating populations [12] seeking out economic opportunity [13,14]. Yet, systematic estimates of this exposure have been elusive [15,16]. Here, we identify from a new global database of 7,764 slow-moving landslides those that sustain human settlements to estimate their exposure across nine di↵erent IPCC mountain-risk regions [1]. Across most of these regions, we find that exposure to slow-moving landslides increases with sprawling urbanized areas, though clearly not with steeper terrain. We show regional contrasts in how exposure to floods may drive people to settle on moving hillslopes. East Asia stands out in how slowmoving landslide exposure increases in more urbanized basins with gentler slopes and less flood exposure. Our findings reveal how disparate knowledge creates uncertainty that undermines an assessment of the drivers of landslide exposure in regions facing increasing mountain risks, such as Central Asia, Northeast Africa, and the Tibetan Plateau.