Taupo News

 

The ongoing seismic unrest period has now lasted for about 10 months.

The decreasing trend itself, starting early this year, reflects in the reduction of the number of earthquakes (find the attached graph below) and returns gradually to levels before May 2022. The rate of the inflation may have decreased as well over the measured period.

Therefore, the alert level for the volcano is being reduced to "Green".

Seismic activity summary

About 1750 shallow earthquake events have been measured beneath the center of Lake Taupō since May 2022. The largest earthquake to date occurred on 30 November 2022 with a magnitude M 5.7 at about 9 km below the lake surface. 4 quakes during the period were recorded with magnitudes of 4 or more. The activity can be divided into 5 sections:

A. 1 Jan 2022 – 30 April 2022: Pre-unrest. This shows a normal level of earthquake activity

B. 1 May – 15 September 2022: Initial period of heightened earthquakes

C. 16 September – 29 November 2022: Earthquake activity is lower, but still above that before unrest started

D. 30 Nov – 31 Dec 2022: Magnitude 5.7 event and it's aftershocks

E. 1 Jan 2023 – 2 April 2023: Earthquake activity is lower, but still above that before unrest started

GNSS (GPS) instruments have registered ground uplift at a rate 60 ± 20 mm per year since May 2022 at Horomatangi Reef in the central part of the lake.

All known seismic unrest periods at the volcano have ended with a lowering of numbers of earthquakes and the rate of uplift by returning to normal, pre-seismic levels. None of these unrest phases have resulted in eruption.

Source: GeoNet New Zealand volcano activity update 5 April 2023