An earthquake measuring 5.4 on the Richter scale jolted 100km SSW of Isangel, Vanuatu at 06:53:07 Hong Kong Time on Thursday(22:53:07 GMT on Wednesday), the U.S. Geological Survey said. The epicenter, with a depth of 40.9 km, was initially determined to be at 20.4259 degrees south latitude and 169.0241 degrees east longtitude.