The Vanuatu Meteorology and Geohazards Department is warning tourists and aviation centres of the drastic change in activity.
Meteorologist Esline Bule said the background noise and gas levels on Ambryn were very significant and while ash has settled a little on Ambae, seismic activity remains at level three, indicating minor eruptions.
"Already Ambae there's a significant ash fall last weekend, in the western part. Ambryn, the volcanic ash is not manifested much yet in the villages. But there's things happening at the top in the crater."