The Upper Waikato Stream Fault is an eastern

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 ...

-bounding north–south striking normal fault in the Ruapehu

Graben In geology, a graben () is a depression (geology), depressed block of the Crust (geology), crust of a planet or moon, bordered by parallel normal faults. Etymology ''Graben'' is a loan word from German language, German, meaning 'ditch' or 't ...

, a seismically active area 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 ...

to the west of

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

. While its own whole fault rupture potential is , such a rupture could be part of a multi-fault rupture.

Geography

It is located near the eastern side of the

Tongariro National Park Tongariro National Park (; ), located in the central North Island, is the oldest national park in New Zealand and the sixth national park established in the world.Department of Conservation"Tongariro National Park: Features", retrieved 21 April ...

, and its surface traces commence to the east of

State Highway 1 The following highways are numbered 1. For roads numbered A1, see list of A1 roads. For roads numbered B1, see list of B1 roads. For roads numbered M1, see List of M1 roads. For roads numbered N1, see list of N1 roads. For roads numbered S ...

where it is known as "''the Desert Road''" and extend to the north east for crossing the top of the

Tongariro River The Tongariro River is a river in the North Island of New Zealand. The part of the Waikato River from the Waihohonu Stream, down to Lake Taupō, was formally named the Tongariro River in 1945. The river originates in the Central Plateau of the ...

and for a short distance into the foothills of the Kaimanawa Mountains.

Geology

The Upper Waikato Stream Fault is one of the eastern wall faults of the Ruapehu Graben and it is immediately to the north of the longer

Rangipo Fault The Rangipo Fault (also known in the past as Desert Road Fault, Whangaehu River Fault, 'Whangaehu Fault) is the eastern Taupō rift-bounding north–south striking normal fault complex of the Ruapehu Graben, a seismically active area of the ce ...

. Its alignment has it as a potential continuation from the west of the Wahianoa Fault. This intersection of the three faults could result in a 7.1 M_W event if all three faults had a total rupture. The fault is normal with a NE strike, and about a 75°W dip. From past to present the slip-rate has changed from /year between 45 and 36.1 ka BP to /year for an active period between 36.1 and 23.65 ka BP and after the

Taupō Volcano Lake Taupō, in the centre of New Zealand's North Island, fills the caldera of the Taupō Volcano, a large rhyolitic supervolcano. This huge volcano has produced two of the world's most powerful eruptions in geologically recent times. The vol ...

Oruanui eruption The Oruanui eruption (also known as the Kawakawa eruption or Kawakawa/Oruanui event) of Taupō Volcano in New Zealand around 25,700 years before present was the world's most recent supereruption, and its largest phreatomagmatic eruption charact ...

it has reduced to /year. It is believed to have been activated by this eruption.

Risks

The current assumed worse case is from a event rupturing this and two adjacent faults over by an average of . A whole fault rupture of the Upper Waikato Stream Fault by an average of would create a event.

References

{{Seismic faults of New Zealand Seismic faults of New Zealand Taupō Volcanic Zone Taupō District