SANTIAGO (AFP) - A strong 6.3-magnitude earthquake shook far northern Chile on Monday, but caused no injuries or damage, Chilean and US experts said. The quake struck at 1635 GMT about 90 kilometers (55 miles) northeast of Calama, a city of more than 100,000 people in the heart of the Atacama desert in the Antofagasta region, the US Geological Survey said. The epicenter of the quake was at a depth of 111.3 kilometers (69.2 miles), the US-based quake monitoring group said. Chile's National Emergency Office put the quake's epicenter closer to Calama and deeper in the earth than the USGS reading.