WELLINGTON - An earthquake with a preliminary magnitude of 6.8 struck south of New Zealand's capital on Friday, according to the US Geological Survey, causing strong shaking and knocking objects off shelves.

The quake, which hit near the northern tip of New Zealand's South Island, was at a depth of about 10 km (6 miles), according to NZ Geonet, which originally reported the magnititude of the quake as 6.0.

The tremor followed a 6.9-magnitude quake in late July.