SINGAPORE/WASHINGTON : A magnitude 7.1 earthquake hit about 100 miles north-northwest of Visokoi Island in the South Sandwich Islands off South America, the US Geological Survey said. The quake’s depth was measured at 9.1 miles deep. The Pacific Tsunami Warning Center said that based on historical data the threat of a widespread destructive tsunami did not exist. Meanwhile a powerful 6.9 magnitude earthquake struck in the far south Atlantic ocean in the inhospitable South Sandwich Islands region, the US Geological Survey said Sunday. The USGS which monitors quakes worldwide initially said the quake was of magnitude 7.1, but later revised its strength downward. It also slightly revised the epicenter’s location.The quake, which struck at 0752 GMT, had an epicenter 154 kilometers (96 miles) northwest of the uninhabited Visokoi Island, and 1,975 kilometers (1227 miles) east-southeast of Stanley, the main city on the Falkland Islands, the USGS reported.The epicenter was at a depth of 16.5 kilometers.