  We show that distinctive alterations in scaling parameters of Dst index time
series occur as a strong magnetic storm approaches. These alterations reveal a
gradual reduction of complexity as the catastrophic event approaches. The
increase of the susceptibility coupled with the transition from anti-persistent
to persistent behavior may indicate that the onset of a severe magnetic storm
is imminent. The preparation of a major magnetic storm could be studied in
terms of "Intermittent Criticality". The analysis also suggests that the
continuous scale invariance is partially broken into a discrete scale
invariance symmetry.
