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Canterbury residents were last night shaken awake by two big aftershocks - exactly a month after the devastating 7.1 earthquake.
The first quake - magnitude 5 and centred 30km east of Darfield - was felt throughout the South Island, including Hokitika and Timaru, at 10.21pm. The second, magnitude 4 and centred 20km east of Darfield, struck eight minutes later.
The two aftershocks hit as Prime Minister John Key hosted a black-tie extravaganza in Auckland to raise money for victims of the September 4 quake.
GNS Science seismologist John Ristau said the 5.0 quake was "quite shallow" and could have damaged property.
"We haven't seen anything that size since the first few days (after the 7.1 quake)," he told The Press.
"If there were structures that were already significantly weakened from the main shock, this could cause a lot more damage than you might normally expect for a magnitude five."
The GNS website this morning listed two reports of heavy damage in New Brighton and West Melton, and 20 "slightly damaging" reports from throughout Christchurch.
A police southern communications spokesman said the only damage call received was of a power pole on a lean, but it was not clear if that could be attributed to the quake.
The quakes have put residents back on edge. There have been more than 1000 aftershocks in the past month.
Christchurch Mayor Bob Parker, who was at last night's fundraiser in Auckland - which raised more than $1 million - said texts started streaming in.
"I got a text straight away from several people, councillors and people I know. I called the chief executive of the airport to check if the airport was okay and that's fine. I feel bad because I'm up here - I'm not experiencing it."
Callers inundated NewstalkZB last night. One man said the first quake lasted about 12 seconds and another told host Tim Dower: "We could hear this one coming. It sounded like a train coming before it hit the back of the house."
The man said Christchurch had just got over the aftershocks. "It scares the hell out of you. There's nowhere to go, nothing you can do. Tonight is going to knock people back to where we were."
"Riccarton was rocking," texted one listener. "This is terrible," texted another.
One resident said his children had clambered under the bed. "Everyone just freaked right out. They are terrified."
"Everyone in Christchurch is so over this," said another man. "You can't sleep. Everyone is on tenterhooks. I'm a tough character, I've been mining ... but I've got three kids, and they're not coping."
Mr Parker said he was anxious to get back home, just to be with the people of the city, to provide comfort through leadership.
"The most this does is bring spirits down. When another aftershock happens, it gets to people. I myself feel it. Even tonight, in this building. Every time the floor trembles I think: 'Oh no, it's an earthquake, I have to run out of the building.' But then I remember I'm okay, I'm in Auckland - it's just a car going past."
The September 4 quake caused at least $4 billion of damage to homes, businesses and infrastructure and has led to 86,000 claims to the Earthquake Commission. About 70,000 of these have come from Christchurch.
About 1000 claims a day are still being lodged. The commission will accept claims for up to three months from the date the damage occurred.
Christchurch earthquake aftershocks: October 2010
View Christchurch earthquake aftershocks: October 2010 in a larger map