A magnitude-6.1 earthquake has shaken northern Argentina, but there were no immediate reports of casualties or damage. The US Geological Survey (USGS) said that the tremor hit at 4:46 a.m. local time (2:46 a.m. EST; 0746 GMT) Monday, about 69 miles (112 kilometers) east-southeast of the city of Santiago del Estero. The USGS also said the earthquake struck very deep: 342 miles (550 kilometers) below the Earth's surface. The Argentinean city of Santiago del Etero has a population of 245,000.