Seafloor instruments reveal more earthquakes on the offshore Hikurangi subduction zone

Data collected from the Hikurangi subduction zone by an international team of scientists led by GNS Science shows there are many more earthquakes happening off the North Island's east coast than currently recorded.

Scientists from New Zealand, Japan and the United States of America have spent the last two weeks at sea on board NIWA’s specialised Research Vessel Tangaroa collecting earthquake monitoring instruments off the coasts of Hawke’s Bay and Gisborne.

These high-tech instruments include a newly developed type of Ocean Bottom Seismometer built by Professor Spahr Webb and his team at Columbia University in New York.

He said the data quality from the new instrument is much higher than he expected, and that he is surprised by the large number of earthquakes they had recorded.

Project Leader Dr Laura Wallace of GNS Science said the initial data collected from the offshore instruments suggests many more earthquakes are happening off the North Island's east coast than can be detected by onshore network of instruments operated by GeoNet.

"We really need instruments offshore the east coast of the North Island, continuously monitoring earthquakes and slow-slip events to get a complete understanding of all the creaks and groans of the Hikurangi subduction zone," says Wallace.

Scientists have also deployed a further five instruments off the coast of Gisborne as part of this research voyage and will collect these instruments in a years’ time.

All the data being collected helps scientists learn more about earthquakes and slow-slip events at the Hikurangi subduction zone, and what this means for future earthquakes in New Zealand.

This research is being undertaken under a five-year, $6 million MBIE-funded Endeavour project led by GNS Science, with major collaboration and contributions from other New Zealand and international partners.

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