A magnitude 6.4 earthquake struck Vanuatu in the South Pacific Ocean, according to seismologists. No tsunami warnings were issued. The earthquake struck at 5:47 p.m. ET on Monday and was centered in the Vanuatu region, according to the United States Geological Survey (USGS). It occurred at a preliminary depth of 6.2 miles (10 kilometers). The epicenter was located about 306 miles (493 kilometers) from Isangel, Vanuatu, and roughly 313 miles (504 kilometers) from Sigatoka, Fiji, the USGS reported. Initial estimates put the quake at magnitude 6.8 before it was revised downward. No tsunami warnin...