This is a 1989 event to a Continental operated PE B747 with tired out engines and a confirmed surge and rundown on the righthand side and then a likely single surge on the left hand side after the crew allows an excessive pitch. The aircraft lost altitude and caused some alarm to the tower when it disappeared below the tree line out of Gatwick.
Agree that most surges are single events over in a second, unless of course the initating cause is not corrected.
The crews actions in this event were criticized in the AAIB report for the excessive pitch