Report on Maroa (New Zealand) — 28 March-3 April 2001
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
28 March-3 April 2001
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2001. Report on Maroa (New Zealand). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 28 March-3 April 2001. Smithsonian Institution and US Geological Survey.
38.42°S, 176.08°E; summit elev. 897 m
All times are local (unless otherwise noted)
On 30 March the IGNS reported that a moderate-sized hydrothermal explosion occurred in the Alum Lakes area, Wairakei, knocking over trees and destroying vegetation near the crater. Water levels at several of the Alum Lakes had dropped several weeks before the explosion.
Geological Summary. The 16 x 25 km Maroa caldera formed sometime after 230 thousand years ago (ka) in the NE corner of the 30 x 40 km Whakamaru caldera, which is the largest of the Taupo Volcanic Zone. The Whakamaru caldera partially overlaps with the Taupo caldera on the south and was formed during the eruption of the Whakamaru Group ignimbrites between about 340 and 330 ka. The Maroa caldera was subsequently filled by at least 70 rhyolitic lava domes or flows, mostly erupted along a SW-NE trend. Lesser amounts of basalt were also erupted. The latest dated magmatic eruption took place about 14 ka, when the rhyolitic Puketarata tuff ring and lava domes were formed (Brooker et al., 1993). The Orakeikorako, Ngatamariki, Rotokaua, and Wairakei hydrothermal areas are located within or adjacent to the Whakamaru caldera. Large hydrothermal eruptions have occurred at the Orakeikorako thermal area during the Holocene, the latest immediately prior to the 1800-year-old Taupo eruption.