Ngauruhoe volcano (New Zealand): minor volcanic unrest
Mon, 23 Mar 2015, 08:4308:43 AM | BY: T
New Zealand's GNS Science reports an increase in earthquakes under the volcano, interpreted as weak signs of volcanic unrest. The Volcanic Alert Level was raised to level 1 (minor volcanic unrest), but no eruption is expected in the near future.
Earthquakes (yellow and red circles) near Ngauruhoe during the past 14 days
from the original report:
"During the last two to three weeks there has been an increase in the number and magnitude of earthquakes being recorded by the GeoNet seismographs around Mount Ngauruhoe. Initial analysis indicates these earthquakes are shallow, occurring at depths of less than about 5 km.
The last significant eruption at Ngauruhoe was in 1975. Earthquakes are not unusual near Ngauruhoe, but it is some time since we last recorded significant numbers or events above magnitude 1. Similar numbers, but smaller events occurred in December 2014. Other swarms of earthquakes near Ngauruhoe occurred in 1983, 1991, 1994, 1995 and again between 2006 and 2010, but otherwise Ngauruhoe usually has little earthquake activity.
The Volcanic Alert Level was raised to Level 1 in June 2006 and then lowered to Level 0 in December 2008 in response to the earthquake activity at that time. No other parameters we measure at Ngauruhoe (gas, temperature) changed during these times.
The current change at Ngauruhoe indicates the volcano has entered a state of volcanic unrest, like we have recorded several times in the last 30 years. No previous periods of unrest have resulted in a volcanic eruption. The outcome of this unrest is more likely than not that there will be no eruption in the short term, like during the 2006-2010 unrest."