An earthquake measuring 6.5 on the Richter scale jolted Puerto Rico early on Monday, the U.S. Geological Survey (USGS) said. The focus of the quake, which occurred at 0401 GMT, was located 56 km north of the town of Hatillo, Puerto Rico, with a depth of 28.51 km under the sea, the USGS said. There were no immediate reports of casualties or damage to properties. The Pacific Tsunami Warning Center said in its advisory that the quake could trigger a local tsunami.