Jul 1 2011 - GeoNet turns 10!

GeoNet Pilot Network

At the time of the launch New Zealand had an ageing and limited sensor network with only a few real-time sites providing data which could be used to rapidly assess geological hazards such as earthquakes, volcanic eruptions, tsunami and landslides. Most of the seismograph stations operating at the time recorded data on cassette tapes which were mailed to us weekly. With the small number of real-time stations, locating earthquakes in a timely manner was difficult. An earthquake north of Auckland in the year before GeoNet launched took over two hours to locate approximately, and over a day before an acceptable location was available. Today, GeoNet operates over 500 sensor network sites of various types with almost all data streamed continuously to the two data centres or delivered when shaking is detected.

The GeoNet website was launched soon after the start of GeoNet. The first serious challenge did not come from an earthquake or volcanic eruption, but from a toy dinosaur which magically appeared in front of the volcano-cam on White Island causing sustained hit rates of 10 per second. By 2005 the website was receiving a few hundred hits per second following a widely felt earthquake. Today a similar earthquake will generate sustained hit rates of over 10,000 per second!

GeoNet website circa 2002

The huge amount of data collected by GeoNet over the last decade has allowed scientists to improve our understanding of New Zealand’s tectonic structure and geological hazards. An example is the discovery of “slow earthquakes” under the North Island where the Pacific and Australian tectonic plates meet. The PositioNZ continuous GPS network, supported by Land Information New Zealand (LINZ), provided the first example of a slow slip event in New Zealand, and the combined PositioNZ and GeoNet GPS networks have seen many since. These events vary in duration and size but are caused by slow movement between the two plates. The movement is often equivalent to a magnitude 7 earthquake but occur over periods of weeks to months rather than seconds.

The most significant challenge of the decade has been, and continues to be, the Canterbury earthquakes, starting with the Darfield M 7.1 event last September. It is sobering to consider that if this earthquake had occurred 10 years earlier there would have been only one real-time station in the whole Canterbury region (the site at McQueen’s Valley that Cantabrians have come to love) and only four in the whole South Island. At that time it would have taken an hour or more to get an acceptable location. Now the front page of the GeoNet website displays the high levels of shaking within a minute or two and an accurate location follows soon after. And the refinements continue as we strive to be even faster using automated systems which can potentially provide good results within a few minutes.

We would like to thank all of the people who have made the first decade of GeoNet a success: a few people with vision of the GeoNet concept, EQC as our major funder, and LINZ who fund the PositioNZ and tsunami networks. A special vote of thanks to all of the landowners who host our sensor network sites – without your support GeoNet could not operate. GeoNet is successful because of the supportive and research orientated culture and dedicated staff here at GNS Science. Thank you all.