An earthquake measuring six on the Richter scale hit New Zealand's South Island on Monday.According to GeoNet, the island country's earthquake monitoring agency, the tremor centred 30 km north-west of Wanaka town, The New Zealand Herald reported.The agency recorded the temblor as "severe".Tremors were also felt as far as the capital city of Wellington which is near the North Island's southernmost point.No casualties or damage to property have been reported yet.