A 7.4-magnitude quake shook the southern Atlantic Ocean early Friday, the US Geological Survey said, with an epicenter 195 miles (316 kilometers) from islands hosting British Antarctic research stations.

There was no immediate tsunami warning following the quake. The USGS reported at least five aftershocks.

The quake struck at 5:32 am local time (0732 GMT) at a depth of 10 kilometers.

It was centered east-southeast of the remote British-administered South Georgia and South Sandwich Islands, which are about 620 miles (1,000 kilometers) east of the Falkland Islands.

The islands are home to two British Antarctic Survey stations that together hold up to 32 researchers, the survey's website said.

Magnitude 5.3 quake hits off northeastern Japan
Tokyo (AFP) Aug 19, 2016 - A magnitude 5.3 undersea earthquake struck Japan Friday off the coast of Ibaraki prefecture, just south of Fukushima, though there were no immediate reports of damages.

The quake struck at about 9:07 pm (1207 GMT) at a depth of some 37 kilometres (23 miles), the US Geological Survey said.

Buildings in Tokyo were shaken by the jolt, but there was no threat of a tsunami from the quake, the Japan Meteorological Agency said.

The crippled Fukushima Daiichi nuclear power plant, battered by a massive 2011 earthquake-generated tsunami and now undergoing decommissioning, has shown no irregularities in radiation levels, a spokesman for operator Tokyo Electric Power told AFP.

Japan sits at the junction of four tectonic plates and experiences a number of relatively violent quakes every year, but rigid building codes and their strict enforcement mean even strong tremors often do little damage.

But the massive undersea quake that hit in March 2011 sent a tsunami barreling into Japan's northeast coast, leaving more than 18,000 people dead or missing, and sending three reactors into meltdown at the Fukushima nuclear plant.

In April, two strong earthquakes hit southern Japan's Kumamoto prefecture followed by more than 1,700 aftershocks, leaving 50 dead and causing widespread damage.