Manaro Voui volcano started erupting last September, prompting Vanuatu authorities to order all 1100 residents of Ambae island to evacuate immediately.
People were allowed to return in October when volcanic activity subsided.
A GNS Science volcanologist, Brad Scott, said however, the volcano had become more active in the last ten days.
"There have been gardens covered by ash, limbs on trees broken. Some of the roofs over buildings and water supplies have since collapsed due to the weight of the volcanic ash."
Brad Scott said water samples from Ambae will arrive in New Zealand tomorrow for testing.
He said an aerial survey by a Royal New Zealand Air Force Orion this week will help authorities assess what's going on.