Prior to 2003, there are two known cases where ultrarelativistic (>or~ 10MeV) electrons appeared in the Earth's inner zone radiation belts in association with high speed interplanetary shocks: the 24 March 1991 and the less well-studied 21 February 1994 storms. During the March 1991 event electrons were injected well into the inner zone on a timescale of minutes, producing a new stably trapped radiation belt population that persisted for ~10 ...