The Poutu Fault Zone is a seismically active area of the central North Island of

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

Geology

The intra-rift Poutu Fault Zone extends from inland of Turangi on the shores of

Lake Taupō Lake Taupō (also spelled Taupo; mi, Taupō-nui-a-Tia or ) is a large crater lake in New Zealand's North Island, located in the caldera of the Taupō Volcano. The lake is the namesake of the town of Taupō, which sits on a bay in the lake's no ...

towards

Mount Ruapehu Mount Ruapehu (; ) is an active stratovolcano at the southern end of the Taupō Volcanic Zone and North Island volcanic plateau in New Zealand. It is northeast of Ohakune and southwest of the southern shore of Lake Taupō, within the Tongari ...

on the east side of the mountain. It has two segments known as the Poutu North fault at long and the Poutu South fault at long and 23 strands have been characterised which probably merge into a single fault plane at depth. The southern end of the Poutu North fault is in close proximity to a number of recently active vents of

Mount Tongariro Mount Tongariro (; ) is a compound volcano in the Taupō Volcanic Zone of the North Island of New Zealand. It is located to the southwest of Lake Taupō, and is the northernmost of the three active volcanoes that dominate the landscape of th ...

. The northern end of the Poutu North fault essentially passes under the volcanic peak of

Pihanga Pihanga is a andesitic volcanic peak in the North Island Volcanic Plateau, located to the north of Mount Tongariro, between Tongariro and Lake Taupo. Lake Rotoaira lies to the south-west of Pihanga, and the smaller Lake Rotopounamu is situated ...

. Accordingly there is the potential for both active faulting and magmatic processes to trigger earthquakes. The relative proportions contributed is important for determining earthquake associated risk and previous assumptions about magmatic processes being dominant are not the case. However magmatic activity is associated with higher earthquake activity and increased slippage rate. This is essentially a tectonic fault zone making up the south eastern intra-rift faults of the Tongariro Graben in the Taupō Rift. The fault zone may well extend beyond the shore line of Lake Taupo. The nearby intra-rift

Waihi fault zone The Waihi Fault Zone is a seismically active area of the central North Island of New Zealand whose earthquakes have been associated with significant loss of life. Geology The intra-rift Waihi Fault Zone extends at least from Little Waihi at L ...

to the west, by about , is parallel. The Poutu fault zone to the south appears discontinuous to the active faults on the eastern side of the Ruapehu graben. Up to magnitude 6.9 earthquakes might occur with a mean of 6.6 about every 550 years along the fault.

References

{{Seismic faults of New Zealand Seismic faults of New Zealand Taupō Volcanic Zone Tongariro Volcanic Centre