From: Extreme geomagnetically induced currents
dB/dt of GICs
Alert level
Criterion
RC (nT/h)
AE (nT/min)
SC (nT/s)
Caution
Dst < −300 nT
100–150
2000
40–110
Warning
Dst < −600 nT
150–400
4000
Emergency
Dst < −900 nT
400–1250
6000
Transient alert
High SEP flux