A volcanic earthquake "swarm" beneath the crater lake of Mt Ruapehu in the central North Island is unusual but unrelated to the eruption on White Island this week. GNS Science volcanologists regularly monitor Mt Ruapehu, an active volcano at the southern end of the Taupo Volcanic Zone in New Zealand. Since Wednesday, volcanologists have been recording a swarm of volcanic earthquakes, and say they have not seen one like it in recent years. There had been no changes in volcanic gas, lake chemistry or lake overflow. "Currently, we are uncertain of the implications of the recent observations," they said on Friday. "However, at this time these changes at Ruapehu are not considered sufficient to change the volcanic alert level." There was a minor eruption on White Island, 49km off the coast of Bay of Plenty, on Wednesday night. But the volcanologists say the changes at Mt Ruapehu are not related to the eruption on White Island. The alert level for White Island has been lowered to two from three. The volcano is no longer erupting but remains in moderate-to-heightened unrest. Volcanologists say the temperature of the crater lake on Ruapehu has been rising since late 2015 and since mid-April has risen from 25C to 40C. Similar temperatures, and rates of increase, were observed in March 2011, April 2014 and February 2015. Mt Ruapehu remains at alert level one, which suggests minor volcanic unrest. Mt Ruapehu is a popular tourist destination, and has some of the most popular walks in New Zealand.