SYDNEY (Reuters) - An undersea earthquake with a magnitude of 6.1 magnitude struck in the remote Southern Ocean south of New Zealand on Wednesday (Sept 20), the US Geological Survey said.

The quake, at a shallow depth of 10 km, was recorded 211 km west of the sub-Antarctic Auckland Island, off New Zealand's South Island, the USGS said.

There were no tsunami warnings issued immediately after the quake.

NZHerald.co.nz said the tremor was initially classified as a strong quake, but was later classified as moderate.

The quake occurred in a seismically active area where there have been some well-documented big shakes recently, the website said.