Dhaka: A powerful magnitude 7.5 earthquake struck in the Drake Passage, located between the southern tip of South America and Antarctica, the Pacific Tsunami Warning Centre reported Friday. The United States Geological Survey (USGS) said the quake, initially measured at magnitude 8, was later revised to 7.5. It struck at a shallow depth of 11 kilometers. According to Philippines News Agency, the epicenter was more than 700 kilometers southeast of Ushuaia, Argentina, a city of about 57,000 residents. Following the tremor, Chile's Navy Hydrographic and Oceanographic Service issued a tsunami warning for its Antarctic territory, noting that the quake occurred around 258 kilometers northwest of the Base Frei research station.