Volcano photos. Gallery 8, Kuirau Park Rotorua, 26/01/2001.

Notes and comments from BJ Scott. (images below)

These notes and comments are based on a visit on Friday evening, and again on Monday.

On Friday 26 January about 3.30 to 3.40 PM NZDT, a muddy hot pool 2.5-3m diameter (Spring 721) burst into eruption, generating the largest hydrothermal eruption in Kuirau Park since 1966. The eruption of blocks and mud was to about 100 metres height and produced a thick carpet of blocks and mud to the east, extending over 120m from the vent. The eruption was very directional. Very little ejecta is distributed to the west (may be less than 30m from the vent). Blocks up to about 1m diameter were projected over 50m from vent, while blocks around 0.1m or less diameter landed over 100m away. The crater formed is about 10-12m in diameter.

It was possible to recognise 4 eruption deposits on Friday evening, and this may give some insight into the eruption. These are;

1) A ballistic block bed, the most widely distributed unit. It would appear that this unit is almost entirely formed from Oranui Formation.

2) A basal dark grey mud deposit directed to the east, ranging from about 400mm thick to a trace of only mm at Ranolf Street.

3) An upper, smaller and slightly lighter grey muds deposit. This was also distributed to the east, overlying the basal darker mud. It was smaller in distribution and the dispersal access was a little more to the SE. Thickness appeared to be about 100-150mm at it’s thickest.

4) A dark grey, very liquid hydrothermal mud distributed to the west, onto the adjacent road. This appears to be the contents of Spring 721.

The ballistic blocks appear to be present through almost all of the deposit. That is there are blocks that are clearly on top of all the mud’s, while other blocks are coated by mud with shelter zones on their leeward sides. Based on first impressions the dark grey liquid mud’s where erupted first, to the west. Then the main phase of the eruption commenced, ejecting mud’s and ballistic blocks to the east, this was followed by a smaller mud rich phase (no relationship with ballistics was ascertained), which was followed by a distinct ballistic shower, numerous cm sized blocks are impacted into all the mud’s. The ballistics extend well beyond the mud’s to the NE and its is not clear from first impressions the exact relationship to the mud’s.

Fallout of the mud layers has loaded all the trees and shrubs within the ejecta apron bending and braking many.