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1.19 Matahina Hydro Dam Seismic Hazard Assessment - New Zealand

  • Commissioned in the late 1960s, the Matahina Dam and 72MW hydro generation facility is situated in a tectonically active part of New Zealand. It suffered damage and began leaking at its abutments during the 1987 M6.3 Edgecumbe earthquake. It was repaired in 1988 and then reassessed and upgraded to meet international safety and performance standards.

  • Against international competition, GNS won the contract to assess the seismic hazards posed to the dam and its reservoir.

  • The GNS study revealed that the Waiohaou fault zone was active and closer to the dam than previously thought. The assessment included geological and fault mapping, gravity profiling, and seismic reflection profiling. GNS concluded that there had been four earthquakes of magnitude 7.2 or greater at or near the dam site in the past 11,500 years.

  • Based on this work, US-based co-contractors, implemented a US$40M strengthening project that allowed the dam and hydro facility to have more than acceptable engineering and safety standards.


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