  Due to the paucity of strong recorded accelerograms, earthquake engineering
analysis relies on accelerogram amplitude scaling for structural
damage/collapse assessment and target spectrum matching. This paper
investigates seismological characteristics of scaled accelerograms so as to
inform future ground motion selection and seismic risk assessment methods. If a
recorded accelerogram is scaled linearly by multiplying it with a positive
factor, it is shown using the Representation theorem and the accelerogram
Fourier spectrum that moment magnitude scales logarithmically and static stress
drop scales linearly. Other seismic parameters such as the Joyner-Boore
distance metric and the effective rupture area are invariant to scaling an
accelerogram. This proposed interpretation of scaling is validated in the time
as well as the frequency domains using a hybrid method for ground motion
simulation. Finally, a discussion is made over the seismological correctness of
accelerogram scaling. It is suggested that a suite of scaled accelerograms can
be considered as being seismologically correct if this suite's magnitude given
rupture area and stress drop distributions are similar to empirical
observations.
