Damage assessment in the case of post-mining-induced seismicity: How to use and adapt macroseismic intensity scales?

Following coal mine closures, the impact of flooding on underground mining excavations and on the geomechanical stability of the rock mass has the potential to trigger superficial earthquakes. The generated vibrations may induce damages to the surface infrastructures. Therefore, they represent a significant source of concern for the population. Nowadays, seismic risk assessment procedures in Europe usually build upon the EMS-98, which has been developed for natural tectonic earthquakes. This study aims to investigate the applicability of EMS-98 to seismic events induced by post-mining context while comparing it to a new intensity scale MSIIS-22 adapted to very low intensities from mining-induced earthquakes. To this end, three damage assessment methods are proposed: application of EMS-98 coupled with a semi-empirical vulnerability approach, direct application of MSIIS-22 and its intensity damage correspondence, and adaptation of the semi-empirical vulnerability approach to MSIIS-22 using observed data. This framework is applied to two testing sites that have experienced mining and post-mining-induced seismic events. The results show that damage estimates from the three methods are similar despite differences in the definition of the intensity degrees and damage states. Further data from post-mining-induced seismic events would be needed in order to confirm these preliminary findings.