Space–time distribution of ancient and active alluvial karst subsidence: examples from the central Ebro Basin, Spain

Sinkholes in the salt-bearing evaporite karst of the Ebro River valley upstream of Zaragoza city (NE Spain)

“…The apparently higher activity of depressions located in developed areas may be related to: (1) the presence of good structural markers to detect subsidence deformation; (2) the triggering or acceleration of subsidence due different types of human activities; and (3) the compaction of man-made ground. Simón et al (2008) provide a subsidence rate of 3.2-4 cm/yr for a sector of a large depression located in El Portazgo industrial estate (Fig. 3).…”

“…Evidence of active subsidence has been recognized in 58% of these sinkholes; 46% of those located in agricultural land and 74% of those situated in urban areas. Subsidence rates have been measured or estimated in 10 points located in large collapse sinkholes filled with man-made ground, ranging from 0.4 to 11 cm/year (Simón et al, 2008;Gutiérrez et al, 2009) (Fig. 3).…”

Assessing karst hazards in urbanized areas. Case study and methodological considerations in the mantle karst from Zaragoza city (NE Spain)

“…Collapses represent the vertical propagation of cavities from the Miocene evaporites through the Quaternary alluvial deposits, finally reaching the surface. Vertical cavities can appear at surface, and depending upon the alluvial thickness, can involve areas with diameters from some meters up to several tens of meters (Mochales et al, 2007;Gutiérrez et al, 2008;Pueyo Anchuela et al, 2010 rates are on the order of 1-2 mm/yr in natural domains (Luzón et al, 2008;Simón et al, 2008;Gutiérrez et al, 2011), reaching 5 to 15 cm/yr in urban settings Pueyo Anchuela et al, 2014a,b). This situation does not exclude the sudden occurrence of collapses without any previous evidence of karst activity (e.g.…”

“…Karst processes have been contemporaneous with alluvial sedimentation (Holocene-Pleistocene; e.g. Luzón et al, 2008;Simón et al, 2008;Gil et al, 2013;Pueyo Anchuela et al, 2014a,b) and are still active. The studied zone is located over one of the Ebro river terraces where the thickness of Quaternary deposits ranges between 20 and 30 m (its variability in the surroundings of Zaragoza city is between 0 and nearly 50 m).…”

Quaternary alluvial sinkholes: Record of environmental conditions of karst development, examples from the Ebro Basin, Spain

“…3A and B) and coexisted with farming activities. An almost steady state could be inferred for that time; comparison of sinkholes identified in aerial photographs of different years shows that their total number remained approximately constant (Simó n et al, 2008). Strong differences between the number of sinkholes in irrigated (mean density 5.8 sinkholes per km 2 ) and nonirrigated fields (mean density 5 1.47) were observed, as well as a high number of sinkholes, about half of them, (Soriano, 1992 and references therein) developed in connection with irrigation channels (Fig.…”