An unusually large event with moment magnitude MW 4.2 occurred on May 18, 2020 in Kiirunavaara Mine (Sweden), followed by very intense aftershock activity for about 2 weeks. A comprehensive interdisciplinary study found that the event was the result of a combination of stress, rock stiffness, strength, structural and mining factors.

In this paper, we concentrate on the observed patterns of seismic source parameters, inferred seismic velocity, and inferred stress and strain changes before and immediately after the large event, to appreciate potential warning signs for future similar events. The observations of the relation between investigated source parameters - apparent stress, energy index and seismic velocity changes - and calibrated stress and strain change from a calibrated mine scale numerical model, add to the understanding of system changes during the event and may assist in future to infer the stability state of parts of the mine, and potentially to identify some emerging instability hazards.