The volcanic earthquake swarm which intensified at Mt Ruapehu around April 25-26 is now declining and the Crater Lake temperature has peaked at 42 °C. A short period of moderate volcanic tremor was recorded on Monday afternoon. Mt Ruapehu remains at Volcanic Alert Level 1 (Minor volcanic unrest).
Since April 25-26 we have been recording a volcanic earthquake swarm beneath the Crater Lake of Mt Ruapehu. The number of events and size has now declined. Swarms of volcanic earthquakes like these are uncommon on Ruapehu in recent years. Seismic activity at Mt Ruapehu is usually dominated by volcanic tremor. A period of moderate volcanic tremor lasting about an hour was recorded from 13:10h on Monday 2 May.
The temperature of the Crater Lake has been rising and since mid-April 2016. It has risen from 25 °C to 42 °C and is now equal to the highest recorded since 2011. The temperature appears to have reached a maximum and no increase has been recorded in the last day.
Currently we are uncertain of the implications of the recent observations. However at this time these changes at Ruapehu are not considered insufficient to change the volcanic alert level. The volcanic alert level for Mt Ruapehu remains at Volcanic Alert Level 1 (Minor volcanic unrest).
GNS Science volcanologists continue to closely monitor Ruapehu through the GeoNet project.