Hipaua geothermal area
The Hipaua Steaming Cliffs are part of an active and moving geothermal field near Lake Taupo. The cliff area has been the source of several devastating landslides in the last 160 years and is a continuing threat to people and property along the Lake shoreline. Find out more about the Hipaua Geothermal Area and the efforts being made to minimise the risk and safeguard its community.
The Hipaua Geothermal Area is situated along State Highway 41 to the northwest of Tokaanu.
The eastern edge of the Little Waihi hamlet, on the southern shores of Lake Taupo, has been devastated twice by landslide debris flows, once in 1846 and again in 1910. These landslides came from a geothermal area known as the Hipaua Steaming Cliffs and flowed down the Waimatai Stream, killing a total of 65 people.
Hipaua Steaming Cliffs overlook the south-western tip of Lake Taupo from the lower slopes of the Kakaramea volcano. The cliff face is part of the Tokaanu-Waihi-Hipaua thermal area and is the surface impression of the Waihi Fault. This thermal area forms part of the Tongariro Volcanic Centre and is located along the western edge of the Taupo Volcanic Zone (TVZ).
The most recent landslide in this area was in July 2002 following heavy rainfall. Over 3,000 cubic metres (m3) of debris were removed from the road and landslide surface, closing State Highway 41 for several days. Although surface vegetation is abundant, the unstable volcanic clays in the area do not provide adequate support for the slopes during long periods of heavy rain.
Landslides in the Hipaua Geothermal Area are likely to be triggered by:
- heat generated by geothermal activity beneath the ground, weakening its soil structure
- the Hipaua thermal field moving northwards
- high rainfall over several days, when ground is already saturated
- the Waimatai and Omoho culverts damming up, spilling water and debris into the road
- an earthquake of Magnitude 6.3 on the Waihi Fault.
Over 1,700 vehicles a day use State Highway 41 (SH 41), which forms part of the main ‘alternate’ route around Lake Taupo. This area is at risk from landslides, with the soil consisting of altered clay and large rocks. During a landslide this material could:
- block culverts
- partially or completely block the road
- create a landslide dam blocking either the Waimatai or Omoho valleys.
Landslides in this area are likely to occur with no warning, putting drivers near Tokaanu at risk from falling rocks and slips from the Hipaua Cliffs and Omoho Valley. Earlier landslides have forced road users living west of Little Waihi Village to find alternate routes to work in Turangi, Taupo and Tokaanu.
There are also threats to the lake edge community at the base of the Waimatai Valley and below the Hipaua Cliffs. These include the:
- failure of the cliff face and existing debris slope along SH 41
- failure of the valley drainage system and (possibly) SH 41
- failure of the debris slope overlooking Little Waihi Village.
The risk of further landslide activity to the existing Waihi Village is also greatly increased because of:
- the steep slope faces of the Waimatai Valley
- weakened, unstable soils in the area
- the presence of remaining debris flows from previous slips, which include large rocks.
Any future development along the lakeshore in the vicinity of this valley is at risk, as are lifeline services such as transport routes (State Highway 41), power transmission lines, communications networks, water and sewerage supplies.
For more information, you can download a copy of the ‘Tephra’ article, ‘Hipaua Steaming Cliffs and Little Waihi Landslide’1 in PDF format from the Ministry of Civil Defence and Emergency Management’s website. You may first need a copy of the Adobe Acrobat Reader programme to view files, which you can download free of charge. To save a PDF to your computer, place your mouse over link, click right-hand mouse button, and select "save target as".
Very high rainfall can trigger slips along the section of State Highway 41 (SH 41) that runs through the Tokaanu-Waihi-Hipaua thermal field. This road forms part of the main ‘alternate’ route around Lake Taupo. There is a significant risk to motorists if there is a slope or road failure from the Hipaua sites.
Upstream of SH 41 culverts from the Waimatai Stream and the Omoho Stream carry sediment and vegetation into Lake Taupo following heavy rain. In extreme storms drainage outlets can become choked with trees and shrubby vegetation that act as dams. As the water level rises it puts pressure on the road and culverts. Water will eventually spill over the road into Lake Taupo, taking with it the accumulated debris.
If the slopes of the Waimatai or Omoho valleys fail, creating a landslide dam, the level of risk increases. Landslide dams and blocked culverts can result in rising ground water levels in surrounding hill slopes. This may cause slips or catastrophic culvert or landslide dam failures.
Slope failures have also been identified above Little Waihi Village. Isolated blocks of rock can be seen within the steep slope above the village in the vicinity of the waterfall. Rock fall from this slope poses a threat to the houses at the northern end of the village, as well as to the village water supply.
- We work with the Taupo District Council to monitor the area, identify risk and develop community-based contingency plans.
- We have commissioned consultants’ reports to outline the hazards with the Taupo District Council
- We will share any other relevant information with other agencies as it becomes available
For policy information on natural hazards, see our Regional Policy Statement.
- Waikato Regional Council - Natural Hazards
- Waikato Regional Council - Civil Defence and Emergency Management
- Waikato Regional Council - Geothermal Activity
- Waikato Regional Council - Earthquakes
- Waikato Regional Council - Landslides
- Waikato Regional Council - Subsidence