Mar 7 1995 - Ruapehu Volcano

A volcano surveillance/research party visited Crater Lake, Mt Ruapehu on 1 March 1995, in order to measure the lake temperature, collect water samples for analysis and make geodetic measurements.

The temperature of the lake was measured as 45.5 °C and the water level had fallen to 15 cm below the outflow level. This value for the lake temperature indicates that the present heating cycle has passed its peak and the lake is starting to cool. The drop in water level is consistent with it being caused by thermal contraction of the water in the lake accompanying this cooling. Geodetic measurements show no significant changes over the last full set of data (May 1994) and are consistent with events of the past few months being a hotter, but otherwise typical, heating cycle. The levels of volcanic tremor and acoustic noise remain elevated above typical background levels for Crater Lake.

Alert Status

We recommend that the Alert Level remains at 2, as the levels of volcanic tremor and acoustic noise remain elevated and the lake temperature remains unusually high. Previous advice on restrictions on access to the Crater Lake area remains in force.

C.J.N. Wilson
Volcanology Programme Leader