Port Vila: A 6.6 magnitude earthquake struck the Pacific Ocean off Vanuatu, said United States Geological Survey (USGS). There were no immediate reports of damage or casualties. Also Read - Magnitude 3.9 Earthquake Hits Shahdol in Madhya Pradesh

The USGS put the preliminary magnitude at 6.6, down from an initial estimate of 6.8. It said it struck at a depth of 47 kilometers (29 miles), making it a shallow earthquake. Also Read - Earthquake Jolts Sikkim-Nepal Border, Tremors Felt in Assam, Bihar, Bengal

The Pacific Tsunami Warning Center said there is no threat of a tsunami as well. Also Read - Earthquake Jolts Los Angeles, Center East of LA International Airport

The Vanuatu Islands are on the so-called Pacific Ring of Fire, an arc of fault lines circling the Pacific Basin that is prone to frequent and large earthquakes. Volcanic eruptions also occur frequently in the region.