A magnitude 7.0 earthquake hit New Zealand, causing widespread damage to Christchurch, the country’s second largest city, on 3 September. No injuries have been reported at this stage and the Pacific Tsunami Warning Center says there is no immediate danger of a tsunami.

Many buildings are damaged and power is out as far away as Dunedin, more than 300 km south. The Avon River, which flows through the city, has overflowed its banks and the Christchurch police report damage to several bridges as well. Christchurch’s mayor, Bob Parker, has asked residents to stay off the roads

The tremor’s epicenter was 30 km west of Christchurch, near two active faults, the Alpine Fault and the Hope Fault. No one yet knows what structure was responsible for this event, says Ryan Gold with the U.S. Geological Survey (USGS) but he adds that the reports are consistent with a right lateral earthquake, in which two crustal plates slip along one another. New Zealand’s South Island lies at the meeting point of the Pacific and Indo-Australian plates.

New Zealand’s biggest earthquake was a magnitude 8.2 earthquake in 1855, centered in the Wairarapa region of the North Island.

The New Zealand Herald has updating reports related to the event.

Updated 9/6/10 10:00 AM: The earthquake has been dowgraded to a magnitude 7.0

Image: Hera Hjartardottir (twitpic: herasings)