MIL OSI – Source: GeoNet Quake & Volcanic Alerts – Volcanic Alert Bulletin: RUA 2015/02 Ruapehu Volcano
Ruapehu Crater Lake heating and intermittent volcanic tremor.
Volcanic Alert Level 1
Aviation Colour Code: Green
3 pm Wednesday 29 April 2015
The Crater Lake is currently in a heating phase which started in late 2014 when the lake was 15°C, reaching a peak of over 40°C in late January–early February 2015 (see RUA 2015/01). The temperature declined to about 31°C in mid March and is now at 37-39°C. We have not observed any other changes at the Crater Lake.
Over the last 2-3 weeks we have been recording intermittent moderate to strong levels of volcanic tremor at Mt Ruapehu, which has been some of the strongest we have seen in the last 8 years. The signals are similar to those in 2006 and 2007 but weaker than those recorded in 1994/1995.
Historically we have not seen a direct relationship between volcanic tremor and discrete volcanic eruptions or sequences of eruptions. However it is one of those signals often present before, during or after enhanced volcanic unrest. Mt Ruapehu remains at Volcanic Alert Level 1 (minor unrest).
The Volcanic Alert Level ranges from 0 to 5 and defines the current status at a volcano.
The Aviation Colour Code for Ruapehu is Green. Aviation Colour Codes are based on four colours and are intended for reference only in the international civil aviation community.
GNS Science continues to closely monitor Ruapehu through the GeoNet project. http://www.geonet.org.nz/volcano