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NZ's tsunami monitoring system in place - 30/09/2010

The likely impact of tsunami on New Zealand’s coastline is now better understood following the completion of a major project to install sea level monitoring devices.

Sea level gauges have been installed at 17 sites around New Zealand and offshore islands. Pressure sensors at the gauges measure any significant change in the sea level, with data being transmitted in real time to GNS Science’s GeoNet data management centre.

GNS Science assesses the data and advises the Ministry of Civil Defence and Emergency Management (MCDEM) about the level of threat posed by tsunami. MCDEM is responsible for managing the response to any threat, which may include issuing public warnings.

The tsunami network project, led by Land Information New Zealand (LINZ), now forms an important component of a wider tsunami monitoring system for New Zealand and across the Pacific.

Graeme Blick, Chief Geodesist at LINZ, said the project was initiated following the devastating Boxing Day 2004 tsunami in the Indian Ocean, caused by a 9.3 magnitude earthquake off the coast of Sumatra. Waves up to 1 metre in height were recorded at sites around New Zealand 18 to 25 hours after the earthquake occurred, highlighting New Zealand’s vulnerability to tsunami.

Mr Blick said the installation took five years to complete, and was made more challenging by the rough and rugged environment in which the sea level gauges were installed, and the long process of obtaining approvals and consents. The last sensor was installed in July 2010.

Agencies involved included GNS Science, MCDEM, NIWA, MORST, Waikato University and consultancy firm URS, as well as Australian agencies involved in the development of a similar network there.

“The fact the network was completed on time and within budget is testament to the cooperative effort that went in to the project,” Mr Blick said.

GNS Science worked closely with LINZ, providing technical expertise throughout the installation phase. Dr Ken Gledhill, Geohazards Monitoring Manager for GNS Science, said the project was a great example of collaboration across the public and private sectors.

Over the past 150 years, New Zealand has experienced about 10 tsunami higher than 5 metres, which can put people and property at risk. Large earthquakes can have devastating effects, both on land and water, Dr Gledhill said, as the people of Christchurch can testify.

“Since installation of the network began in 2005, several large regional and distant earthquakes have generated tsunami,” he said. “The network has successfully detected these, including the 2009 Samoan and 2010 Chilean earthquakes and the resulting waves that hit our coastline.”