Quakes increasing: volcanic alert raised for Mount Ngauruhoe after 40 year slumber

March 2015 – NEW ZEALAND - GNS Science has increased the volcanic alert level for Mount Ngauruhoe after an increase in the number of earthquakes around the volcano. Duty volcanologist Art Jolly said the change at Ngauruhoe indicated the volcano had entered a state of minor volcanic unrest prompting the alert level to be lifted from zero to one. During the past three weeks there has been an increase in the number and magnitude of earthquakes recorded by the GeoNet seismographs around Mt Ngauruhoe.

Swarms of earthquakes around Ngauruhoe have been recorded in the past, most recently in December 2014. Jolly said it was “more likely than not” the unrest would not result in an eruption in the short term. GNS Science would continue to monitor the volcano closely. Initial analysis indicates the earthquakes around the volcano were shallow, occurring at depths of less than about 5kms. The last major eruption at Ngauruhoe was in 1975 although earthquakes near the volcano are not unusual.

Mount Ngauruhoe is an active stratovolcano or composite cone in New Zealand, made from layers of lava and tephra. It is the youngest vent in the Tongariro volcanic complex on the Central Plateau of the North Island, and first erupted about 2,500 years ago. Although seen by most as a volcano in its own right, it is technically a secondary cone of Mount Tongariro. The volcano lies between the active volcanoes of Mount Tongariro to the north and Mount Ruapehu to the south, to the west of the Rangipo Desert and 25 kilometres to the south of the southern shore of Lake Taupo. –Stuff NZ