WELLINGTON -- A strong earthquake measuring 7.0 on the Richter scale struck off the coast of the South Pacific island nation of Vanuatu early Tuesday, the U.S. Geological Survey reported.

No tsunami warning was issued by the Pacific Tsunami Warning Center and there were no immediate reports of casualties or damage.

The quake, which occurred at 05:52 a.m. Tuesday Vanuatu local time (19:52 GMT Monday), was centered about 225 km north of Luganville on the island of Santo, northern Vanuatu, at a depth of121.8 km.

Another quake of 6.6 magnitude was recorded on Monday.