Geologic Background:
The 17-km-wide Rotorua caldera is the NW-most
caldera of the Taupo volcanic zone. Rotorua is the only
single-event caldera in the Taupo volcanic zone and was
formed about 220,000 years ago following eruption of the
>500 cubic kilometers rhyolitic Mamaku ignimbrite. 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, has been
restricted to lava dome extrusion without major explosive
activity.
Historic Activity:
- The major thermal areas of Takeke, Tikitere, Lake
Rotokawa, and Rotorua-Whakarewarewa are located within
the caldera or outside its rim.
- Whakarewarewa contains New Zealand's last remaining
active geyser field.
Recent Activity:
- On Sept. 18, 2000 a hydrothermal eruption occurred
from a spring.
- On Jan 26, 2001 a hydrothermal eruption occurred from
a spring. Largest since 1966.
Data Sources:
- Global Volcanism Network (V. 25, No. 10 to V. 26, No.
3).
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