I've just found out: the first international help offered was by the US military in Hawaii.
It wasn't needed, as we had very few people trapped, but the offer was made, and since out anti-nuclear stance has resulted in a widening gap militarily between NZ and the US, It was a generous offer.

Andrea's post says it all. There were eruptions of silt in Christchurch like small volcanos. It happened in the wee small hours, and our houses are built with earthquakes in mind, and don't fall down on you.
The buildings which suffered most were very old -by our standards- listed heritage stone buildings downtown, with very few people in them. About 90 buildings will be demolished, mostly lovely old ones.