Sep 14 1999 - Taupo Volcanic Centre

The September 1999 deformation survey (lake levelling) about Taupo Volcanic Centre has just been completed. Lake levelling surveys at Taupo are conducted every three months. The results from the September 1999 survey show only small changes from the June 1999 survey (see TPO-1999/03). The major trends identified in previous surveys are still present. These trends are:

1. Uplift about the lake centre, including Horomatangi Reef, Scenic Bay, Rotongaio and Motutaiko Island areas;
2. Subsidence along the northern shores, with the maximum occurring at Kinloch. The rate of subsidence is declining.

Figure 1: Time series plots showing height changes (mm) at selected sites.

The subsidence along the northern shores, represented by data from Kinloch in Figure 1 above, has been observed since the early 1980’s. The rate of subsidence has been decreasing over the last 2 - 3 years and the latest data continues to support that observation. Uplift about the lake centre has been observed since mid-1996. The latest results show a minor decline in the rate of these uplift trends.

Only minor earthquake activity has occurred within Taupo Volcanic Centre between June and September.

The Alert Level for Taupo Volcano remains at Level 0.

Brad Scott
Volcano Surveillance Co-ordinator