Geologic Background:
The Tarawera Rift is a feature within the
Okataina volcanic center, which is defined by the
Haroharo caldera and the Haroharo and Tarawera rhyolite
dome complexes. The caldera formed between 250,000 and
50,000 years ago during the eruption of at least four
ignimbrite sheets. In the last 10,000 years, lava domes
and related pyroclastic deposits have filled much of the
caldera.
Historic Activity:
- Phreatic explosions have been recorded 17 times from
1886 to 1973.
- Most famous eruption was in 1886 when a 17 kilometer
long fissure erupted 1.3 cubic kilometers of basaltic ash
and hot mud in one night burying three villages.
Recent Activity:
- Short intense sequences of earthquakes have occurred
in the area in February 1983, February 1986 and November
1987. All earthquakes appeared to be of tectonic
origin.
Data Sources:
- Smithsonian's SEAN Bulletin (V. 12, No. 11)
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