Integrating geomorphological mapping , trenching , InSAR and GPR for the 1

13 This contribution illustrates the advantages of integrating conventional 14 geomorphological methods with InSAR, ground penetrating radar and trenching for 15 sinkhole mapping and characterization in a mantled evaporite karst area, where a 16 significant proportion of the karstic depressions have been obliterated by artificial fills. 17 The main practical aim of the investigation was to elucidate whether buried sinkholes 18 overlap the areas planned for the construction of buildings and services, in order to 19 apply a preventive planning strategy. Old aerial photographs and detailed topographic 20 maps were the most useful sources of information for the identification of sinkholes and 21 helped to obtain information on their chronology, either a minimum age or bracketing 22 dates. The InSAR technique provided subsidence rate values ranging from 4.4 to 17.3 23 mm/yr consistent with the spatial distribution of the mapped sinkholes. This quantitative 24 deformation data helped corroborating independently the existence of active buried 25 sinkholes and improving the delineation of their limits. The GPR profiles contributed to 26 the precise location of sinkhole edges, provided information on the geometry of buried 27 sinkholes and deformation structures and helped to site trenches and to rule out the 28 existence of sinkholes in particular areas. The main input derived from the trenches 29 includes: (1) Confirming or ruling out anomalies of the GPR profiles attributable to 30 subsidence. (2) Precise location of the edge of some filled sinkholes. (3) Information on 31 subsidence mechanisms recorded by various deformation structures and cumulative 32 subsidence magnitude. (4) Calculating minimum long-term subsidence rates using 33 radiocarbon dates obtained from deformed sinkhole deposits. (5) Unequivocal evidence 34 of active subsidence in areas assigned for the construction of buildings. 35 36