Strong earthquake clusters are still hitting Christchurch today, sending goods toppling from shelves, causing rockfalls and driving terrified residents from buildings 10 months after a quake killed almost 200 people in the city.
An initial 5.8 magnitude earthquake at 1.58pm was centred 20km north-east of Lyttelton at a very shallow depth of 8 km.
It was followed by a series of strong aftershocks, the largest at 3.18pm measuring 6.0 magnitude revised from 5.3, which locals corrected reported earlier as feeling worse than the initial quake at 1.58pm.
The most recent one was at 4.50pm measuring 5.0 with a depth of 10km, 20km north-east of Lyttelton.
No tsunami warning has been issued.
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Now, there's a warning from a scientist there would be further shakes.
"In coming days the most likely scenario is that there'll be a series of aftershocks in a similar location, and they'll gradually drop off," Ken Gledhill a seismologist with GNS Science told TVNZ News this afternoon.
"This is just a reminder that this area is more active than it was in September 2010."
New Zealand straddles the boundaries of the Indo-Australian and the Pacific tectonic plates and is hit by about 14,000 quakes every year, of which only a small number usually top a magnitude of 5.
Scientists had warned after the February quake that there would be further shakes, probably as large as magnitude 6.
No serious injuries or damages
Following the shakes this afternoon, a number of people have received minor injuries, and at least one required hospital treatment, but there are no immediate reports of serious damage, injuries or casualties at this stage.
St John responded to 19 emergency calls from the first quake. It said all the injuries have been minor.
The majority were chest pains, people collapsing, people having
seizures, panic attacks and anxiety issues.
There was one minor car accident and one person had a knock to their head.
Four people have been rescued by the Coastguard after being trapped by rock falls in Boulder Bay.
Police said there are significant rockfalls at Redcliffs and a stopbank on New Brighton Road has collapsed.
A partly demolished building on the corner of Barbadoes and Kilmore Streets has collapsed, but the Fire Service advises there was no-one inside..
A vacant house at Aynsley Terrace has also collapsed.
The WINZ building in New Brighton has been damaged, but all its staff were evacuated safely.
Scarborough rock face has suffered some collapse but this has been contained by the containers at the foot of the cliff.
People are also being urged by police to stay away from hill suburbs because of the risk of rock falls.
Phone networks are under pressure and police are urging
residents keep mobile calls for emergency use and to text rather
than phone otherwise.
Travel and evacuations
ONE News reporter Jack Tame described the first large shake at 1.58pm as "pretty fast and pretty violent", while Christchurch Mayor Bob Parker said "we are very concerned."
Parker adds that the psychological impact of today's earthquake and aftershocks are big.
He said nothing can prepare Cantabrians for more earthquakes, and is urging people to stay off the streets to keep them clear in case of emergency.
Christchurch Airport has re-opened, coming after runways, navigation systems and buildings were fully assessed.
Chief Executive Jim Boult said there has been no damage to the airports runways, which are now open for landings and departures.
He said the terminal is open and he expects flight operations to re-commence about 6pm.
Boult warns there will be significant delays and some flight cancellations, and it will likely be well into tomorrow before the backlog is cleared.
He said people should check with their airlines before going to the airport.
The airport was evacuated then closed earlier this afternoon following the first large tremor of 5.8 magnitude at 1.58pm.
People outside the airport said they heard a loud roar and the cars in the parking building started moving from side to side.
One News reporter Joy Reid was driving at the time of the first quake and said it felt like someone was pulling on the wheels of her car, causing her vehicle to swerve across the road.
She said all motorists pulled over and stopped, and residents came spilling out of their homes and buildings.
TV ONE's Close Up reporter said Abby Scott said earlier today that people were shaken and that traffic was backed-up.
There was severe traffic congestion in some areas, including around the Palms Mall and New Brighton Road.
There were reports of major holes on Broadhaven Avenue.
But police said while there's significant traffic on the city streets, it's not gridlocked at this stage.
The Lyttelton tunnel is open.
Police are urging drivers to slow down and stay off the roads if you do not need to travel.
ONE News reporter Jack Tame, who is in Christchurch for his holiday break, told ONE News that there are cues for petrol.
But Petrol chain Z adds that there's plenty of fuel in the city.
It said stocks are high for the holiday season, and there was a delivery via coastal tanker into the Port of Lyttelton today.
It said the infrastructure appears sound and is operational so there's no need to queue or panic buy.
It said all its stations are in good shape, but three at New Brighton, Linwood and Shirley have no power.
ONE Sport reporter Toni Street said trees started to rattle and lasted 20 to 30 seconds during the initial strong shakes.
Riccarton Mall has since been deemed structurally safe following an evacuation on what was one of its busiest days of the year.
However, management are yet to decide whether to re-open today, awaiting decision of letting staff back in.
Earlier today the mall was the first to evacuate with thousands of people spilling onto the streets.
One person has been taken to hospital after being injured at Eastgate Mall when the quake hit this afternoon.
The quake came 10 months after a 6.3 quake hit the city killing about 180 people.
The New Zealand dollar briefly dipped to $0.7725 from $0.7740 in thin trading after news of the quake, before recovering. New Zealand stocks cut pared gains to trade up 0.14%.