In this paper we present an application that exploitsa geographic information system as a front-end of acomplex information system supporting the managementof landslide hazard in Valtellina, an alpine valley inNorthern Italy. A decision support system (EYDENET, operational sinceOctober 1996), incorporating a geographic informationsystem and a data interpreter based on artificialintelligence techniques, processes the readings of the250 most significant instruments of a monitoring netof about 1000 sensors installed on differentlandslides in several alpine valleys. Data gathered by extensometers, clinometers andpluviometers, to check both movements of rocks andclimatic conditions which could affect them, areprocessed by EYDENET, that provides on-lineinterpretation of data, helps the users analyse them,and generates natural language explanations and alarmmessages for the people responsible for theenvironmental management and the civil protection.