Defacing the map: Cartographic vandalism in the digital commons

This article addresses the emergent phenomenon of carto-vandalism, the intentional defacement of collaborative cartographic digital artefacts in the context of volunteered geographic information. Through a qualitative analysis of reported incidents in WikiMapia and OpenStreetMap, a typology of this kind of vandalism is outlined, including play, ideological, fantasy, artistic, and industrial carto-vandalism, as well as carto-spam. Two families of counter-strategies deployed in amateur mapping communities are discussed. First, the contributors organise forms of policing, based on volunteered community involvement, patrolling the maps and reporting incidents. Second, the detection of carto-vandalism can be supported by automated tools, based either on explicit rules or on machine