Waihi Fault Zone Explained

Waihi fault zone
Other Name:Waihi North fault, Waihi South fault
Named For:Waihi Village
Pushpin Relief:1
Country:New Zealand
Region:Waikato Region
Range:Up to 7.2 Mw
Segments:2
Length:38km (24miles)
Strike:N-S
Displacement:2.6mm/yr±0.8mm/yr [1]
Plate:Indo-Australian
Status:Active
Type:Normal fault
Age:Miocene-Holocene
Volcanic Arc/Belt:Taupō Volcanic Zone
Embed:New Zealand geology database (includes faults)

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 38km (24miles) from Little Waihi at Lake Taupō towards Mount Ruapehu on the west side of the mountain.[1] It has two segments known as the Waihi North fault and the Waihi South fault and at least 19 fault strands (three of which were previously known as the Taurewa Fault). Together they make up the south western intra-rift faults of the Tongariro Graben in the Taupō Rift. The northern part of the Waihi South fault which is about 18km (11miles) long is just to the west of the recently active vents of Mount Tongariro so there is the potential for both active faulting and magmatic processes to trigger earthquakes. Some northern fault strands also pass through the presumed extinct Kakaramea-Tihia Massif volcano, although this is still associated with geothermal activity at the Hipaua Steaming Cliffs. The fault zone has the potential to be associated with up to 7.2 magnitude earthquakes with recurrence intervals of mean 6.6 magnitude earthquakes between every 490 and 1380 years. There is now good evidence from LiDAR that it extends to the north in a three fault complex another 14km (09miles) on land or even beyond the shore line of Lake Taupo.[2] The nearby intra-rift Poutu fault zone to the east, by about 10km (10miles), is parallel to the Waihi fault.[1] The active Taurewa and Rotopounamu faults that have been separately named by some are now assigned to the two fault zones.[3] [2] To the west of the Waihi Fault Zone the National Park Fault is the current western wall fault for the modern Taupo rift.[2]

Risks

Large landslides have occurred in the Hipaua Steaming Cliffs area of the Waihi fault escarpment and it is likely that some the large historical loss of life by New Zealand standards from these landslides has been related to earthquake activity on the fault.[4]

References

-39.061°N 175.634°W

Notes and References

  1. Gómez‐Vasconcelos. Martha. Villamor. Pilar. Procter. Jon. Palmer. Alan. Cronin. Shane. Wallace. Clel. Townsend. Dougal. Leonard. Graham. 2018. Characterisation of faults as earthquake sources from geomorphic data in the Tongariro Volcanic Complex, New Zealand. 10.1080/00288306.2018.1548495. New Zealand Journal of Geology and Geophysics.
  2. Web site: Active fault mapping in the south western bays (Pukawa, Omori, Kuratau) of Lake Taupō: Response to requests 2021. 2023-04-19.
  3. Crustal extension in the Tongariro graben, New Zealand: Insights into volcano-tectonic interactions and active deformation in a young continental rift . 2017. Geological Society of America Bulletin . 129 . 9-10 . 10.1130/B31657.1 . Martha Gabriela . Gómez‐Vasconcelos . Pilar . Villamor . Shane J . Cronin . Jon . Procter .
  4. Web site: C.M.. M.P.. Severne. Hochstein. Heat and mass transfer of the Hipaua thermal area (Tokaanu – Waihi geothermal area) Lake Taupo, New Zealand. 1994.