| Borehole instrument boosts earthquake monitoring in Auckland 9 May 2008 A new borehole earthquake recorder installed by GNS Science will boost earthquake and volcano monitoring capability in the Auckland region.
The instrument has been installed at the bottom of a 250m-deep disused Auckland Regional Council borehole at Riverhead, about 20km northwest of Auckland City.
It is the deepest seismic instrument in New Zealand and forms part of a network of six earthquake instruments around Auckland designed to pick up early signs of volcanic unrest in the Auckland Volcanic Field, which extends from Papakura to Orewa. The other five instruments are on the ground surface.
The Auckland Volcano Seismic Network is part of a national network of seismic instruments operated under the GeoNet Project, a division of GNS Science.
GeoNet Project Director, Ken Gledhill, said placing the instrument in a deep borehole eliminated disturbance from ground vibration, common to all big cities.
“ The sound of a big city masks the shaking caused by earthquakes and makes monitoring of small tremors very difficult. By recording down a borehole, rather than at the surface, much of this ground noise vanishes,” Dr Gledhill said.
The borehole seismic recorder is made by The University of Auckland and the signal is transmitted by radio in real-time and available to scientists running the national GeoNet monitoring system.
“It is a great example of cooperation by several organisations,” said GeoNet Volcano Network Coordinator Craig Miller.
“Following the success of the Riverhead recorder, we are looking at installing similar recorders in unused boreholes at Herne Bay and Karaka in South Auckland,” Mr Miller said.
This will bring the Auckland Volcano Seismic Network to eight instruments. GNS Science hopes to install a further two instruments, on Waiheke Island and Whangaparaoa Peninsula, in the future.
While the earthquake hazard in Auckland is not high by New Zealand standards, the focus of the recording instruments in Auckland is on small earthquakes that might precede an eruption of the Auckland Volcanic Field. By getting away from human ground noise, a borehole recorder will enable better data to be collected that can be used to give timely warning of a possible future volcanic eruption in Auckland. Elevated earthquake activity is one of the signs of volcanic unrest. Aucklanders could expect to get days to weeks warning of a possible eruption after earthquake activity starts.
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Contact:
Craig Miller, GeoNet Volcano Network Coordinator, GNS Science, P: 07-374-8211
Dr Ken Gledhill, GeoNet Project Director, GNS Science, P: 04-570-1444 |
