Declining temperatures at the Mt Ruapehu's Crater Lake has seen volcanologists lower the mountain's Volcanic Alert level from Level 2 to Level 1.

The Aviation Colour Code has been changed from Yellow to Green.

Activity at Ruapehu has calmed down since May 11.

The earlier volcanic unrest recorded in May this year is no longer present, says GNS volcanologist Natalie Balfour.

The Volcanic Alert Level is now lowered to Volcanic Alert Level 1, meaning there is minor volcanic unrest.

The gas emissions decreased and the level of volcanic tremor has also declined. The temperature of the summit Crater Lake has declined from 46 degrees Celsius on May 11 and is now at 23 degrees Celsius.

A gas flight was completed on Monday and recorded the gas output at levels typical of background for Mt Ruapehu, says Natalie.

The elevated level of volcanic tremor which was at moderate levels has declined and shows now similar levels to what it was in the second half of 2015.

Data available at present indicates the period of elevated volcanic unrest at Mt Ruapehu is over, says volcanologist Natalie Balfour.

GNS Science volcanologists continue to closely monitor Ruapehu through the GeoNet project.