Washington: A strong earthquake of 6.3 magnitude shook far northern Chile on Monday, experts from the US Geological Survey said.

It 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 USGS said.

The epicenter of the quake was at a depth of 111.3 kilometers (69.2 miles), the US-based quake monitoring group said. However no immediate damage or casualties were reported.

The Pacific Tsunami Warning Center measured the earthquake at 6.6-magnitude, but said no  tsunami threat existed.