Scientists are seeking help to recover five instruments recording earthquakes at New Zealand's largest and most active fault, the Hikurangi subduction zone, after they failed to surface during attempts to recover them.

The hi-tech earthquake monitoring instruments, valued at $30,000 each, belong to GNS Science and Columbia University in the United States and went missing from the seafloor along the Hikurangi subduction zone off the North Island's East Coast.

The instruments were deployed on the seafloor off the Hawke's Bay coast in late 2018, and had been recording earthquakes at New Zealand's largest and most active fault.

The instruments are about the size of a washing machine, are mounted on steel frames, and have large yellow floats. It is possible they may float to the surface of their own accord and wash up anywhere along New Zealand's east coast.

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The missing earthquake monitoring instruments. Photo / GNS Science
The missing earthquake monitoring instruments. Photo / GNS Science

They are marked with the contact information of either GNS Science, or Columbia University on the side of them.

Although most of the instruments installed were successfully recovered last year, a few of them did not respond to their release signal during a recent voyage on R/V Tangaroa.

Dr Laura Wallace, GNS Science, said instruments went missing occasionally as operating them in very deep water was technologically challenging.

"The information recorded on the instruments is very valuable to us, and we would love to hear from anyone if they find one of these sensors washed up on the shore," Wallace said.

Wallace said anyone who had found an unusual piece of equipment such as this should contact GNS Science at 04 570 1444.

Initial data from the seafloor instruments suggested many more earthquakes were happening off the North Island's East Coast than could be detected by the onshore network of instruments operated by GeoNet.

The data 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.

The Hikurangi subduction zone: a credible magnitude 8.9 earthquake and tsunami scenario. Video / East Coast LAB

Wallace said the focus of the research project will help to understand how, why, and how often the Hikurangi subduction zone moved in slow-slip events and large earthquakes.

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

East Coast LAB (Life at the Boundary) is a collaborative programme that brings together scientists, emergency managers and other experts, with the community from across the East Coast to makes it easy and exciting to learn more about natural hazards and how they affect us.