The land cover on landslide scars was determined based on the land cover in the surrounding areas to avoid possible bias due to any modification of vegetation cover after landslide occurrence. The land cover information was digitised on orthorectified images

in ArcGIS software to obtain land cover maps for each year analysed. In order to focus on the impact of humans, the eight land cover classes were regrouped into two broad classes: (i) (semi-)natural environments and (ii) human-disturbed environments. The (semi-) natural land cover is here defined as the land cover that is not or only slightly selleck screening library affected by anthropogenic disturbances, and is composed of natural forest and páramo. The BMS387032 human-disturbed land cover includes all land cover types that result from

human occupation (degraded forest, matorral, agricultural land and pine plantations). A multi-temporal landslide inventory was created based on the aerial photographs and the satellite image. A stereoscope was used to detect the landslides based on the aerial photographs. Local variations in tone, texture or pattern, and the presence of lineaments were used to infer slope instabilities; similar to the methodology described in Soeters and van Westen (1996). We identified features as fresh landslides only when clear contrasts in vegetation density and cover with the surroundings were observed. Digitisation of landslide patterns was done in ArcGIS software where the planimetric landslide area was obtained. As it was not always possible to differentiate depletion, transport and deposition areas, the total landslide area is likely to be overestimated as it might include depositional areas. Field data obtained in 2008, Cell press 2010 and 2011 allowed us to validate the landslide inventory of 2010. This validation indicated that the landslide inventory from the remote sensing data was almost complete, and that only a very few small landslides were omitted mainly because their

size was close to the minimal mapping area. Although the inventory covers a time span of 48 years (1963–2010), landslides were only detectable at four discrete times (date of the aerial photographs and satellite image) and correspond to morphologically fresh features produced shortly before the date of the image. Our observations during intensive field campaigns in the Eastern Cordillera suggest that landslide scars are recolonised by vegetation in less than three years’ time, making them undetectable on any optical remote sensing data. The landslide inventory, thus, unavoidably misses landslides that occurred and disappeared during the time lapses between the analysed images.