Of the 100 seismometers that were deployed on the seafloor east of Gisborne late last year, 97 were successfully recovered. Photo / Supplied
Of the 100 seismometers that were deployed on the seafloor east of Gisborne late last year, 97 were successfully recovered. Photo / Supplied
Scientists say they've lost track of three quake-detecting devices that were on loan from Japan - and want to hear from anyone who spots them.
The three ocean-bottom instruments that have been recording seismic waves from earthquakes and other sources did not respond when scientists sent an acoustic signal to them from a ship during the recovery voyage in March.
Of the 100 that were deployed on the seafloor east of Gisborne late last year, 97 were successfully recovered.
The bright yellow spherical instruments, about the size of a large beach ball, had been used to collect a CAT-scan-like image of the tectonic plates deep under the East Coast, and might yet wash up anywhere along the Tairawhiti Coast.
They carried the markings, GNS Science (NZ) plus some Japanese characters.]
"The instruments are valuable and we would like to return them to our Japanese colleagues who kindly loaned them to us for the duration of the project," said leader of the New Zealand team Stuart Henrys, a geophysicist at GNS Science.
The international project that will continue until October, has involved the deployment of several hundred onshore and offshore seismic instruments to record seismic waves from earthquakes and from ships that generate pulses of sound directed at the seafloor.
The data collected by the onshore and offshore instruments is combined and helps scientists create a 3D image of the subduction zone down to a depth of about 15km below the surface.
The bright yellow spherical instruments, about the size of a large beach ball, had been used to collect a CAT-scan-like image of the tectonic plates deep under the East Coast. Photo / Supplied
"This gives scientists an insight into the properties of the rocks on either side of the plate boundary," Henrys said.
The Hikurangi plate boundary, a huge geological feature below the seafloor east of Gisborne, is where the Pacific tectonic plate dives beneath the Australian plate.
Henrys said the focus of the research project will help to understand how, why, and how often the Hikurangi plate boundary fault moves in large earthquakes.
"The Gisborne region is an ideal natural laboratory to study how plate boundary faults behave."
Rebecca Bell, a geophysicist at Imperial College London and lead UK scientist on the project, said the dense deployment of seismographs on land and on the seafloor was a world first for the science community and provided an opportunity to develop images of unprecedented quality and resolution.
Bell said most of the 200 land-based instruments had been recovered, but 50 seismographs would remain in place until October to record additional earthquakes.
"The 3D imaging project is embedded in even larger East Coast-wide seismic project of the Hikurangi margin, that has been ongoing over the summer and will enter a second phase early in 2019," Henrys said.
"We would love to hear from anyone if they find one of these Ocean Bottom Seismometers washed up on the shore."
The scientists asked anyone finding an unusual piece of equipment such as this to contact GNS Science at 04 570 1444.
GNS Science would organise collection and cover the cost freight.
