An earthquake measuring 6.1 on the richter scale hit off the coast of the South Pacific island of Vanuatu on Monday. The US Geological Survey said the quake struck at a depth of 59 kilometres around 160 kilometres south of the capital Port Vila. Vanuatu had been hit by a series of quakes in recent weeks including one of 7.5 magnitude on the 21st of last month and one of 7.0 magnitude on Sunday.