The application of GPR and ERI in combination with exposure logging and retrodeformation analysis to characterize sinkholes and reconstruct their impact on fluvial sedimentation

Abstract

This work illustrates the practicality of investigating sinkholes integrating data gathered by ground penetrating radar (GPR), electrical resistivity imaging (ERI) and trenching or direct logging of the subsidence‐affected sediments in combination with retrodeformation analysis. This mutidisciplinary approach has been tested in a large paleosinkhole developed during the deposition of a Quaternary terrace on salt‐bearing evaporites. The subsidence structure, exposed in an artificial excavation, is located next to Puilatos, a village that was abandoned in the 1970s due to severe subsidence damage. Detailed logging of the exposure revealed that the subsidence structure corresponds to an asymmetric sagging and collapse paleosinkhole with no clear evidence of recent activity. The sedimentological and structural relationships together with the retrodeformation analysis indicate that synsedimentary subsidence controlled channel location, the development of a palustrine environment and local changes in the channel pattern. GPR profiles were acquired using an array of systems with different antenna frequencies, including some recently developed shielded antennas with improved vertical resolution and penetration depth. Although radargrams imaged the faulted sagging structure and provided valuable data on fault throw, they did not satisfactorily image the complex architecture of the fluvial deposit. ERI showed lower resolution but higher penetration depth when compared to GPR, roughly capturing the subsidence structure and yielding information on the thickness of the high‐resistivity alluvium and the nature of the underlying low‐resistivity karstic residue developed on top of the halite‐bearing evaporitic bedrock. Data comparison allows the assessment of the advantages and limitations of these complementary techniques, highly useful for site‐specific sinkhole risk management. Copyright © 2016 John Wiley & Sons, Ltd.

Identifying the boundaries of sinkholes and subsidence areas via trenching and establishing setback distances

“…In the deeper area the sinkhole fill reaches 7-9 m in thickness. This should be These features may be interpreted as inversion artefacts related to collapse faults or fault zones (e.g., Zarroca et al, 2017;Fabregat et al, 2017). The ERI and geological sections shown in figure 5 illustrate the interpreted faults and fissures and their correspondence with those exposed in the trenches.…”

Sinkholes in hypogene versus epigene karst systems, illustrated with the hypogene gypsum karst of the Sant Miquel de Campmajor Valley, NE Spain

“…However, in areas with sharp lateral changes in resistivity related to tectonic or collapse faults, this unrealistic assumption results in the occurrence of artificial highand low-resistivity nodes that overprint the actual resistivity configuration of the subsoil. Nonetheless, the identification of such inversion artifacts allows the identification of fault zones (e.g., Sevil, 2018; Zarroca et al, 2012Zarroca et al, , 2017.…”

Geomorphological Dating of Pleistocene Conglomerates in Central Slovenia Based on Spatial Analyses of Dolines Using LiDAR and Ground Penetrating Radar

“…Among them, the GPR method provides the highest resolution images. It has been widely used to image the structure of dolines and to locate the potential collapse dolines [42][43][44][45][46][47][48]. …”