Abstract
Abstract. Two earth fissures appeared in Murcia province (southeastern Spain) after the flood occurred because of a heavy downpour on 28 September 2012. In this area, located within the Guadalentín Valley, up to 212 L m−2 was reported that day. More than 200 agricultural exploitations were destroyed by the flooding, with a devastating effect on many infrastructures, such as a main A-7 highway bridge that collapsed in this event. The earth fissures appeared after this flooding in the towns of Puerto Lumbreras and Totana. The first fissure showed a straight-line direction approximately parallel to the main geological structures of the Guadalentín Valley. The total length of the fissure was 400 m and was 2 to 3 m in depth. The soil in the fissure is classified as a low-plasticity silt with some sand and clay, ML, according to the Unified Soil Classification System. From the sieve and hydrometer tests, the percentage of silt in these samples was between 48 % and 68 %, the clay content between 12 % and 30 % and the sand content between 2 % and 40 %. The plasticity index was smaller than 9.2 for all the samples. To evaluate the piping and internal erosion susceptibility of the soil, pinhole, crumb and geochemical tests were done on the collected samples. A result of non-dispersive soil was obtained from crumb and pinhole tests. Nevertheless, the pH, sodium adsorption ratio and exchangeable sodium percentage tests showed that some samples could be affected by the dispersion of the soil. Also, the collapsible potential of the soil was studied, showing negative results for all the samples except for that collected at the southern end of the fissure, which showed a medium to high potential. Concerning the Totana fissure, it appeared with different branches and holes instead of as a rectilinear pattern. The total length of the fissure was 190 m, with the soil characterized as a silty soil. Lastly, INSAR data, GPS, GPR and land subsidence maps were used to study the possible origin of these fissures.
Highlights
Earth fissures are open-ground fractures that form in unconsolidated sediments as the result of tensional stresses applied in the ground
The soil affected by the earth fissure in the Saudi Arabia case (Bankher and Al-Harthi, 1999) was a Quaternary alluvium soil classified as a low-plasticity silt
The mapping of the Puerto Lumbreras earth fissure is shown in Fig. 1, modified from Mulas (2013)
Summary
Earth fissures are open-ground fractures that form in unconsolidated sediments as the result of tensional stresses applied in the ground These fissures are usually associated with land subsidence due to water withdrawal (Arizona Geological Survey, 2019; Schumann and Poland, 1970). This kind of fissure associated with land subsidence has been reported in many places around the world, as in Arizona (USA) (Jachens and Holzer, 1982), Saudi Arabia (Bankher and Al-Harthi, 1999) or China (Zhang et al, 2008; Hu et al, 2019).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
