An earthquake measuring 6.4 on the Richter scale hit the Santa Cruz islands in the South Pacific on Friday. The fresh tremors came a day after a series of huge quakes sparked a region-wide tsunami alert. Seismologists said the quake was centered about 314 kilometres north-northwest of Santo, Vanuatu, at a depth of 9 kilometres. The quake struck at about 8:16 am (local time). No tsunami warning has been issued.