Identification and Mitigation of Subsidence and Collapse Hazards in Karstic Areas: A Case Study in Alcalá de Ebro (Spain)

Sinkholes are a severe problem in urban areas located karstic regions, especially where evaporitic rocks such as gypsum exist. Identification and proposal of mitigation measures needed to reduce this geo-hazard effect on buildings social living. This paper presents case study the town Alcalá de Ebro (Spain), which is highest sinkhole risk region Europe. The identification series sinkholes that appeared analyzed. former involves geological investigation, including boreholes, field tests geophysics. latter addressed by use geogrids, mortar injections polyurethane injections. A complementary finite element analysis carried out set ground behavior associated with sinking process assess its future evolution. River appears be main cause sinkholes, results show treatments applied were successful their purpose, there no apparent deformations indicating subsidence or still active area. different techniques depending size sinkhole, objectives pursued affected discussed.