Safety first is the message authorities want to convey as many displaced locals face a second night away from their homes.

Some residents in the earthquake zone may be without power until the end of the week, says lines company Orion.

New Zealand's Caroline Powell and mount Lenamore lead the field at Burghley after the Cross Country stage.

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.

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.

Christchurch residents are recounting terrifying ordeals during this morning's 7.1 magnitude earthquake.

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