Nov 5 1997, 3:10 pm - Ruapehu Volcano

The ongoing minor eruptive activity from Crater Lake has continued this week with two steam eruptions through the crater lake, one on Monday afternoon (2:40 pm) and one yesterday afternoon (5:03 pm). Both were accompanied by volcanic earthquakes.

Monday's event was not observed due to the weather conditions. Observations on Tuesday from the eastern side of the volcano confirmed an eruption had accompanied the volcanic earthquake recorded on Monday. Fresh light grey mud and ash coated the snow to the west of the summit crater. It also appeared that a small flood had passed down the Whangaehu Glacier into the Whangaehu River valley.

Tuesday evening's event occurred under very clear conditions and the resultant steam plume was well observed. This resulted in some over-reporting by the media.

Observations this afternoon, from an overflight by DoC and other personnel on the mountain confirm that small floods were generated about the crater lake by these steam eruptions. Water and mud has also flowed into the Whangaehu valley. Some fresh impact craters are also present about the crater. Geysering and convection is occurring in the crater lake.

Volcanic tremor levels increased slightly after Monday's event and have remained slightly above background since that time.

In summary, activity has increased over the last two days, but not enough to warrant the Alert Level being raised from one to two at this time. Further reactivation of activity could occur while the background seismic level remains slightly elevated.

The Alert Level remains at Level 1.

Brad Scott (for C.P. Wood)
Volcanology Section Leader