The Paeroa Fault is a seismically active area in the

Taupō District Taupō District is a territorial authority district in New Zealand. It covers 6,333 km² of land, and a further 610 km² of lake area, including Lake Taupō, New Zealand's largest lake, and Lake Rotoaira. The district stretches from th ...

Waikato Region The Waikato () is a Regions of New Zealand, region of the upper North Island of New Zealand. It covers the Waikato District, Waipā District, Matamata-Piako District, South Waikato District and Hamilton, New Zealand, Hamilton City, as well as ...

of the central

North Island The North Island ( , 'the fish of Māui', historically New Ulster) is one of the two main islands of New Zealand, islands of New Zealand, separated from the larger but less populous South Island by Cook Strait. With an area of , it is the List ...

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

Geology

North of

Lake Taupō Lake Taupō (also spelled Taupo; or ) is a large crater lake in New Zealand's North Island, located in the caldera of Taupō Volcano. The lake is the namesake of the town of Taupō, which sits on a bay in the lake's northeastern shore. With ...

, volcanic

ignimbrite Ignimbrite is a type of volcanic rock, consisting of hardened tuff. Ignimbrites form from the deposits of pyroclastic flows, which are a hot suspension of particles and gases flowing rapidly from a volcano, driven by being denser than the surrou ...

at least thick, and called the Paeroa Ignimbrite (dated to 339 ± 5 ) is exposed along the very steep fault scarp of the Paeroa Fault that defines the western flank of the high Paeroa Range. The Paeroa Ignimbrite appears to have been erupted from a linear vent alignment parallel to the current Paeroa Range and fault. This fault area of the

Taupō Rift The Taupō Rift is the seismically active rift valley containing the Taupō Volcanic Zone, central North Island of New Zealand. Geology The Taupō Rift (Taupo Rift) is a intra-arc continental rift resulting from an oblique convergence in the H ...

is displacing at a rate of /year. At the north eastern end of the fault is the geothermally active

Maungaongaonga Maungaongaonga is an high dacite volcano located between Rotorua and Taupō in the North Island Volcanic Plateau. The area of the mountain is a scenic reserve and some of its southern slopes are highly geothermally active. Geography Maungao ...

volcano that with the fault defines the far south western border of the Ōkataina Volcanic Centre. The

Ngapouri-Rotomahana Fault The Ngapouri-Rotomahana Fault is a seismically and volcanically active area of the central North Island of New Zealand. Geology Coming from the south the Ngapouri-Rotomahana Fault can be interpreted as a splay of the Paeroa Fault beneath the s ...

too extends to the

Ōkataina Caldera Ōkataina Caldera (Ōkataina Volcanic Centre, also spelled Okataina) is a volcano, volcanic caldera and its associated volcanoes located in Taupō Volcanic Zone of New Zealand's North Island. It has several actual or postulated sub calderas. The ...

and is a splay from the Paeroa Fault. The southern portion of the fault is associated with the raised Paeroa Fault block immediately to its east which is the largest ground surface fault block within the

Taupō Volcanic Zone The Taupō Volcanic Zone (TVZ) is a volcano, volcanic area in the North Island of New Zealand. It has been active for at least the past two million years and is still highly active. Mount Ruapehu marks its south-western end and the zone runs n ...

. The raised block further to the east goes into the down lands associated with the Reporoa Caldera that extend to form the Taupo-Reporoa Basin. To the west is the adjacent Te Weta Fault block in what has been called the Paeroa Garben, a rift valley that extends to the much more inactive now Horohoro Fault.

Risks

This intra-rift fault has been estimated to have single event earthquakes in its northern portion about 6.4 Mw and for the whole fault, rupture intensity of about 6.8 Mw with up to upward displacement. Almost half of rupture events in the last 16,000 years have been associated with nearby volcanic eruptions so it is not only the direct earthquake impact that may be important. The Mamaku eruption of about 8000 years ago and Rotoma eruption of about 9500 years ago of the

are associated in time with deposits indicating the earthquake fault rupture events took place either just before or during the eruption sequence.

References

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