EG28: Identification of an air-filled collapse by using ERT and SRT geophysical methods. A case study from Latvia

This study investigates a recently formed ground collapse by applying electrical resistivity tomography (ERT) and seismic refraction tomography (SRT) methods. The findings reveal that the newly developed karst cover collapse sinkhole is associated with the highly soluble gypsum rocks prevalent in the region. This case study demonstrates the challenges and limitations in identifying a relatively small collapse sinkhole associated with great geotechnical and environmental risks and the potential need for more detailed studies. The air-filled cavity could be confidently identified by ERT survey only using dense electrode spacing (1 m between electrodes) and formed a low resistivity anomaly in the inverted section. The SRT survey did not confidently identify the location of the sinkhole despite the use of dense geophone spacing and the cavity being filled with air.