Aviation Colour Code is used as a guideline for international civil aviation, and reflects the potential impact of volcanic eruptions on that industry.

The Te Maari area on Tongariro continues to produce steam and volcanic gases and an eruption could still occur with little or no warning. The Volcanic Alert Level therefore remains at 1.

Last week numerous reports were received regarding potential eruptions from Te Maari, but these reflected weather conditions and natural variations in steam and gas emissions. GNS volcanologist Michael Rosenberg said, “As soon as the weather gives a good steam plume the phones start ringing. We are all going to have to get used to steaming at Tongariro. It might continue for years and vary substantially from time to time, even if we get no more eruptions.”

Tongariro has had no eruptive activity since an explosion on 21 November 2012. Earthquake activity has been negligible since before the November 2012 eruption and the flux of volcanic gases has remained relatively low and stable for several months.

Through the GeoNet project GNS Science continues to monitor Tongariro for any earthquake activity, makes frequent measurements of volcanic gas concentrations and keeps a close watch for any visible changes.

Background Aviation Colour Codes are based on four colours and are intended for quick reference only in the international civil aviation community. Code Green indicates that a volcano has no eruptive activity.

The Volcanic Alert Level ranges from 0 to 5 and defines the current status at a volcano. Level 1 indicates volcanic unrest, with departures from background levels.

Steven Sherburn Duty Volcanologist