Weren't I a souless android I'd have cried when I first heard about it. The Ministry of Truth -truth be told- was just a tiny rock a few meters over Vivec, it wasn't as if a giant meteor hit the island...and damn those Argonians too, can't wait to put them slaves in their place.
Well, the meteor would have originally been moving at the usual speed for such objects, about 10-30 km/s. For comparison purposes, a similar object, no more than 50 meters in diameter, exploded over Tunguska (Siberia) in 1908.
http://en.wikipedia.org/wiki/Tunguska_event
This was an air blast, so the damage was somewhat amplified. But still, it was estimated to produce an explosion roughly equal to a large thermonuclear bomb.
The Ministry of Truth is about the same size, and if it resumed its original momentum before being magically stopped, then we can say with some confidence that it would level the whole southern half of Vvandenfell. Now, you may say that conservation of momentum prevents this, but conservation of momentum has already been thrown the wind when Vivec stopped it.
So yes, the impact is larger than you might think.