Aftershocks rattled New Zealand's Christchurch, hours after two earthquakes struck the city and terrified residents there.
The strongest aftershock, a shallow 5.1 magnitude tremor, struck early in the morning at 6.37am local time (5.37pm Irish time), just 21km from the earthquake-devastated city.
It was part of a swarm of 25 earthquakes of magnitude 3.0 or stronger to shake the already fragile city overnight, and sets up a tense Christmas period for Christchurch residents.
The latest earthquakes come 10 months after a devastating quake that claimed 181 lives in the city.
Two shallow quakes of magnitude 5.8 and 5.9 and a series of aftershocks struck on Friday as malls were packed with afternoon Christmas shoppers, sending stock tumbling from the shelves and turning the festive mood to panic.
The quakes, which temporarily closed the international airport and disrupted communications, were the latest in a series that began 15 months ago and have destroyed much of the inner-city.
Local news media reported people fleeing in fear as the quake and a first wave of aftershocks rattled the city, leading to liquefaction and flooding in some suburbs worst hit by previous earthquakes.
Liquefaction is caused when shaking loosens the bonds between soil particles, turning the ground into a quagmire.
The lives of people in New Zealand's second largest city have been shattered by the series of earthquakes that began in September last year when a 7.0 tremor struck.
That quake caused widespread destruction but because it hit just before dawn there were few casualties.
But on 22 February, a lunchtime 6.3 quake killed 181 people and reduced much of the downtown area, including the city's Anglican cathedral, to rubble, while in the suburbs thousands of homes were damaged or destroyed.
The cost of repairing the city has been put at NZ$20bn (€11.9bn).
Smaller earthquakes in the 3.0-4.0 range have become an almost daily occurrence in Christchurch but only a few thousand from a population of more than 350,000 people are reported to have left the city.
Deputy mayor Ngaire Button said the latest quakes coming at the end of a difficult year, were likely to prompt more people to consider leaving the city but she doubted many would go.
The US Geological Survey said a 5.8-magnitude quake struck at 1:58 pm (12.58am Irish time) Friday at a depth of less than 5km.
It was followed 70 minutes later by a 5.9 tremor at about the same depth.
One person was rushed to hospital after being injured in a shopping mall and the National Crisis Management Centre was activated.
Civil Defence controller David Coetzee said the toll could have been much higher had the central business district not been cordoned off after earlier quakes.
Telephone services were cut in many areas and electricity supplies disrupted, but police said there were no reports of other injuries or widespread damage.
The international airport and shopping malls were all evacuated and closed as a precautionary measure.
Airport chief executive Jim Boult said flights resumed in the early evening.
Police spokesman Stephen Hill said a few buildings collapsed and people were also urged to stay away from hill suburbs because of a risk of rock falls.
New Zealand sits on the so-called "Ring of Fire" the boundary of the Australian and Pacific tectonic plates, and experiences up to 15,000 tremors a year.
