Since April 26 we have been recording a volcanic earthquake swarm beneath the Crater Lake of Mt Ruapehu. Swarms of volcanic earthquakes like these are uncommon on Ruapehu in recent years. Seismic activity at Mt Ruapehu is usually dominated by volcanic tremor.

The temperature of the Crater Lake has been rising since late 2015 and since mid-April 2016 the Crater Lake temperature has risen from 25 °C to 40 °C. Similar temperatures and rate of temperature increase were observed in March 2011, April 2014 and February 2015.

We have not noted any changes in other monitored parameters like volcanic gas, lake chemistry or lake overflow. A gas flight was performed on March 30 and the Crater Lake was sampled on April 14.

Currently we are uncertain of the implications of the recent observations. However at this time these changes at Ruapehu are not considered sufficient to change the Volcanic Alert Level.

GNS Science volcanologists continue to closely monitor Ruapehu through the GeoNet project. The changes at Mt Ruapehu are not related to the volcanic eruption that occurred at White Island on Wednesday 27 April.

Agnes Mazot Duty Volcanologist