LKAB measures and reports vibrations on the ground for seismic events in millimetres per second. The value shown is called Peak Particle Velocity, and is the greatest value that occurs regardless of the direction of the vibrations. Earlier vibrations were reported in the vertical, i.e. upright, since the instruments followed a Swedish standard that stipulated that only vertical vibrations should be measured. The instruments have been replaced, and from February 2015 LKAB reports in Peak Particle Velocity.