Tongariro volcano (New Zealand): seismic swarm, a possible precursor to new activity
23 July, 2012
Tongariro volcano is showing signs of a possible awakening. On 13 July 2012, an increase in small (<M2.5) earthquakes was detected. The quakes were clustered at depths of 2-7 km under the area between Emerald crater and Te Mari crater. More than 20 earthquakes were recorded until 20 July, when the seismic activity peaked and prompted GeoNet to raise the alert level from 0 to 1. Compared to a background average of 2 quakes per year, the swarm is significant and could indicate magma movements. Seismic activity dropped on 21 July with only 1 quake since then, but preliminary measurements show an increase in volcanic gas emission. NZ Scientist started to increase their monitoring at the volcano.