Tsunami warning issued after 7.8 magnitude quake rattles New Zealand

No casualties reported; citizens have been asked to watch out for aftershocks

A powerful 7.4-magnitude earthquake rocked New Zealand late today, the US Geological Survey said.

The shallow tremor hit just after 11:00 pm local time, some 90 kilometres from the South Island city of Christchurch, according to the agency.

However, the Pacific Tsunami Warning Center did not issue a warning following the quake and there were no immediate reports of casualties.

"Based on all available data a destructive Pacific-wide tsunami is not expected," reported the center.

The New Zealand government's GeoNet website said the quake was "felt widely" throughout the country and warned citizens to watch out for aftershocks.

Tamsin Edensor, a mother of two in Christchurch, said the shaking lasted a "long" time.

"We were asleep and woken to the house shaking, it kept going and going and felt like it was going to build up," she told AFP.

She said there was no sign of damage on her street and the power was still on, adding that she was worried about towns and villages closer to the epicentre.

"We're getting aftershocks at the moment. We're going to stock up on water supplies just in case."

In September, a strong 7.1-magnitude earthquake struck the east coast of New Zealand, generating a small tsunami, but no significant damage or injuries were reported.

In February 2011, a 6.3 earthquake left 185 people dead in the South Island city of Christhurch.

New Zealand is on the boundary of the Australian and Pacific tectonic plates, which form part of the so-called "Ring of Fire", and experiences up to 15,000 tremors a year.