New Zealand's Christchurch was rocked by a series of earthquakes on Monday even as vivid memories of a devastating earthquake in February that killed about 180 people had hardly faded.

As many as ten people have been reportedly taken to hospitals after they were wounded as buildings collapsed following a magnitude 5.5 earthquake hit the city.

The tremor was followed by a stronger quake of magnitude 6 hours later but no fresh injuries have been reported so far.

The nature of the injuries was not immediately revealed, but there were Twitter posts saying the injuries were 'moderately serious'.

They've had 5 earthquakes in 2 hours in Christchurch. In ascending strength. This concerns me, Mark Pesce wrote on Twitter. On Tweet described the second tremor as 'extremely strong'.

Another update on the social networking site said Christchurch Airport has been evacuated and terminal building and runways are being checked.

The epicenter of Monday's quake was 10 kilometers east of Christchurch, at a depth of 11 kilometers. The first quake shook the city at 1 PM and the tremors were felt as far away as Wellington and Invercargill.

The February 22 earthquake had a magnitude 6.3.