—This paper describes a methodology based on Answer Set Programming (ASP) to work with incomplete geographic data. Source geographic data which describes a risk zone is translated to ASP description and it allows to solve query’s which can not be solved by a normal GIS. An evacuation plan can change when new situations are presented, for instance traffic, a zone in extreme danger or other natural modification of the zone to be evacuated. Since 1994, Risk Management Office in Mexico has declared around 30 km from the Popocat´epetl Volcano crater a danger zone. This office defined several roads to evacuate the people when a Volcano event can be presented. Our approach allows to simulate and to give support to generate new evacuation plans. The results developed by the ASP approach can be translated to a visual format and can be incorporated to a GIS to develop other kind of analysis by using the geographic data.