The Manaro Voui volcano on Ambae island has started emitting ash and volcanic gas, triggering fears of an imminent eruption. The government has ordered all 11,000 residents of the island to leave immediately. Officials have raised the activity measure of the volcano to level four, on a scale in which level five represents a major eruption. Ambae is one of about 65 inhabited islands in the Pacific nation about one-quarter of the way from Australia to Hawaii. The last time the Ambae volcano erupted was in 2005.