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Seismographs part of nuclear monitoring effort - 12/05/1999

A global network of 170 seismographs, including three in New Zealand territory, will be part of a United Nations initiative to monitor the Comprehensive Nuclear Test Ban Treaty.

The seismographs, which will be linked by satellite to a UN data centre in Vienna, will be located in the Bay of Plenty, Canterbury, and on Raoul Island.

The Canterbury and Bay of Plenty seismographs will be owned and operated by the Institute of Geological & Nuclear Sciences Limited (GNS). The two instruments will enhance the Institute’s existing national network of seismographs.

The seismograph at Raoul Island will be owned and operated by the United States.

GNS seismologist Warwick Smith, who has been a New Zealand representative on the Treaty planning group for 15 years, said the seismograph network would be the main tool for detecting underground explosions.

" Scientists have learnt quite well how to tell the difference between large nuclear explosions and earthquakes, but there are still problems in distinguishing small explosions from earthquakes," Dr Smith said.

" The network has to be so good at detecting small nuclear detonations, and distinguishing them from earthquakes, that it will act as a deterrent."

The best available sites had been selected worldwide to make the network as effective as possible. A good site was well away from traffic and other artificial sources of "noise" such as the sea, rivers, or human activity. It also needed to be on solid rock.