Raoul Online

New Zealand’s northernmost chain of volcanoes, the Kermadec Islands, came online yesterday when GeoNet added a new seismograph and webcam to their website.

Wednesday 27th May 2009

A team from GeoNet visited Raoul Island volcano in the Kermadecs earlier this month to install monitoring equipment that will make tectonic and volcanic activity in the island chain more accessible to New Zealanders. Whilst there they installed two tsunami gauges, two seismographs, volcano monitoring instruments, GPS monitoring, a webcam, and lake level and temperature monitors.

The equipment will monitor the active volcano known as Raoul and provide useful information on the tectonic earthquakes that occur in the area where the Australian and Pacific tectonic plates collide. The tsunami gauges will dramatically extend the reach of New Zealand’s tsunami detection network, providing information about waves generated in the south-west Pacific Ocean that might affect our coasts.

The first of the two seismographs was put on the GeoNet website yesterday morning, showing a small number of earthquake events against a noisy background. The noise is not thought to be significant tremor or telemetry noise but highlights the fact that every site has its own peculiarities and requires fine-tuning as it joins the GeoNet network. It could be that the trace is set too sensitively for the seismograph and needs to be backed-off to provide meaningful data. This work will take place over the coming days as GeoNet staff integrate the instruments with the rest of the network.

The installation includes two tsunami gauges in separate locations on Raoul Island that will provide a dramatic improvement in the ability to detect tsunami waves from the south-west Pacific that might affect New Zealand shores. One or both of the Raoul Island gauges will join the tsunami network within about a week once the necessary changes have been made to the databases and webpages to accept and present the incoming data.

The webcam, already online, offers a view of both Green and Blue Lakes, parts of Raoul Island’s active geothermal system.

Data from the instruments on Raoul Island arrives at GeoNet’s data centres via satellite link. It is then processed through various databases, and information selected for display on the webpages is prepared for publication. This will take more or less time, depending on the information, so the data on the website should be considered as “near real-time.” With the data now flowing in, GeoNet staff have to make the final adjustments to integrate the information with the rest of the network, and the processing delay for various instruments will soon be apparent.

Raoul Island is largely uninhabited, apart from a small team of Department of Conservation staff who carry out weed control, meteorological observations and other conservation work. This explains why GeoNet has installed two of each instrument, where possible. Servicing remains a challenge, and any failures can only be addressed on planned visits. It is not yet clear whether both seismographs, tsunami gauges etc. will appear on the website in the long-term. Data from the dual instruments will be available to scientists but, in most cases, only one set will be presented on the website. The alternate instrument will be made available in the case of a failure to keep the website updated until the next scheduled maintenance visit makes repairs possible.

With the instruments now commissioned and the data flowing in, the GeoNet website will be fine-tuning the presentation of the data over the next two to three weeks.

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