Report on Rotorua (New Zealand) — 5 November-11 November 2003
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 5 November-11 November 2003
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2003. Report on Rotorua (New Zealand). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 5 November-11 November 2003. Smithsonian Institution and US Geological Survey.
38.08°S, 176.27°E; summit elev. 757 m
All times are local (unless otherwise noted)
Two eruptions occurred at Kuirau Park in Rotorua caldera around 1100 on 6 November. They blasted mud, rock, and ash 14 m into the air. Gray mud and small rocks littered a zone ~20 m wide. The eruption destroyed trees around the crater. The eruptions occurred just meters from the site of a large blowout in 2001. The area is known for this kind of phreatic activity.
Geologic Background. The 22-km-wide Rotorua caldera is the NW-most caldera of the Taupo volcanic zone. It is the only single-event caldera in the Taupo Volcanic Zone and was formed about 220,000 years ago following eruption of the more than 340 km3 rhyolitic Mamaku Ignimbrite. Although caldera collapse occurred in a single event, the process was complex and involved multiple collapse blocks. The major city of Rotorua lies at the south end of the lake that fills much of the caldera. Post-collapse eruptive activity, which ceased during the Pleistocene, was restricted to lava dome extrusion without major explosive activity. The youngest activity consisted of the eruption of three lava domes less than 25,000 years ago. The major thermal areas of Takeke, Tikitere, Lake Rotokawa, and Rotorua-Whakarewarewa are located within the caldera or outside its rim, and the city of Rotorua lies within and adjacent to active geothermal fields.