Geothermal subsidence and land movement is a natural phenomenon in geothermal areas which can be exacerbated by operating geothermal generation facilities. Subsidence is caused by pressure decline in compressible geological formations, and has been observed in the Wairakei-Tauhara geothermal system since the early 1960s. Typically subsidence in geothermal areas occurs over a large area and very gradually which causes minimal effects on the surface. However, subsidence anomalies have been detected in the Crown Road area, Spa-Rakaunui Rd area and in the Wairakei Valley.
Contact Energy operates several geothermal operations on the Wairakei-Tauhara geothermal system and undertakes a significant amount of work to understand why subsidence occurs and how it can be mitigated and managed. They work with independent experts at GNS Science to predict future rates of subsidence in the known 'subsidence bowls' in the Wairakei-Tauhara geothermal system and have independent land movement monitoring in place, with routine surveying of over 3,100 survey marks spread across 120 square kilometres.
If you would like to know more about subsidence in the Wairakei-Tauhara geothermal area please contact Contact Energy on 07 376 2100.