The first stage of New Zealand’s tsunami monitoring network has gone live, offering data from four tide gauges to the public in near real-time.
New Zealand’s tsunami monitoring network, due for completion in 2010, will consist of 20 monitoring stations located on mainland New Zealand and selected island locations. Designed to monitor tsunami waves in the south-west Pacific area, the network is a collaborative effort between New Zealand, Australia and other countries in the south-west Pacific.
The first stage of the network is now available to the public, showing near real-time graphs of tide levels at four stations on the GeoNet website, with the raw data being made available to the scientifically-minded after a delay.
Data from tide gauges located at Gisborne, Napier, Wellington and the Chatham Islands can be viewed in the tsunami section of the GeoNet site. The graphs show relative tide levels recorded at the sites over the previous 36 hours, clearly illustrating the variation between high and low tides. Each trace shows the mean tide level (the dark line) calculated from the maximum and minimum readings taken at regular intervals. The grey shaded area shows the variation that occurred during the sampling period.
An explanatory brochure, which describes tsunami formation, the network and how it works is available as a pdf here.
The tide gauge image can be found here: New Zealand Tsunami Monitoring Network.
At this early stage, the information displayed by the tide gauges offers little in the way of early warning of a tsunami event. Three of the four gauges are located on mainland coasts, and the Chatham Island gauge is the only one located at a significant distance. However, it is not clear whether a tsunami wave generated by a large quake off the coast of South America would be displayed by the Chathams gauge in sufficient time for the public to take appropriate action.
As with all technology, it will be how experts analyse the data supplied by the network of gauges. Interpreting whether a small incoming wave is likely to be followed by a larger one is best left to experts in the field. It is these experts who continue to analyse the tsunami risk imposed by a particular event and are responsible for issuing official warnings.
Nevertheless, the gauges now available for public scrutiny will provide some reassurance that experts have correctly interpreted the risk posed by a particular event and, on occasions when a small wave does intercept our coasts, the gauges will show that the event has passed even though most members of the public were unable to detect a change in sea level at the time.
As the network is extended it will improve our ability to detect incoming tsunami waves and identify their landfall on our coasts. The knowledge gained from studying these smaller events will enable better forecasting and management of larger events.
[Compiled from data provided by the Geonet project and its sponsors EQC, GNS Science and FRST.]