A strong quake of magnitude 6.8 struck north of Antarctica. The US Geological Survey said the quake's epicenter was 98 kilometre northeast of Visokoi Island, part of the South Sandwich Islands archipelago, a British overseas territory. <br/><br/>The quake was very shallow, at a depth of only 10 kilometre below the seabed. The US Pacific Tsunami Center said the quake was not expected to cause a tsunami.