A detailed description of an intense flash of auroral emissions that occurs equatorward of the dayside auroral oval observed with the IMAGE-FUV imagers is presented. The comparison of simultaneous snapshots of this subauroral flash obtained with the three FUV cameras indicates that proton precipitation is dominant. This transient proton aurora is triggered by the sudden increase of a solar wind dynamic pressure pulse. It occurs on closed field lines mapping to the equatorial plane at distances as small as ~4 RE. A second similar event is presented, and several other cases are mentioned. These shock induced transcient emissions develop with a time scale of a few minutes (typically ~5 min), and have a relaxation time on the order of ~10 minutes.