The 7.1 magnitude tremor that shook the South Island caused the most damage since the 1931 earthquake that flattened Napier.

The displaced of Christchurch were last night in makeshift shelters across the city, fearful of waking up again to more violent tremors.

Kyle Scott and Liz Blatch still had their wedding at Darfield's Oak historic homestead only hours after the 7.1 earthquake.

A formal curfew is now officially in place in the Christchurch central business district until 7am and those who breach it may be arrested, say police.

Christchurch Mayor Bob Parker says there is "significant structural damage" to his city after this morning's 7.1 quake, with some eastern suburbs facing possible evacuation.

Members of the public found a toddler, aged 20 months, floating in a pond in Nelson's Queens Gardens this morning.

The savage bashing and stomping of a 16-yr-old in Christchurch was recorded on a mobile so the video could be put on the net, a court hears.

Maurice Williamson's comments that opponents of land sales to foreigners were sometimes being racist was a case of humour backfiring, John Key said today.