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Seismometer deployment Hikurangi subduction zone October - November 2017

The Tangaroa assisted in New Zealand’s largest ever deployment of seafloor earthquake recording instruments in a bid to learn more about the earthquake behaviour of the tectonic plates beneath the east coast of the North Island.

NIWA research ship Tangaroa was chartered by GNS Science to lower 100 Ocean Bottom Seismometers (OBS) onto the seafloor of the Hikurangi subduction zone. They were placed in a grid pattern from offshore Wairarapa through to East Cape.

These instruments, along with land-based seismometers record echoes from within the Earth from both naturally occurring earthquakes and from acoustic signals generated by a US research ship, Marcus Langseth, which will be positioned off the East Coast. This will enable scientists to create images of the plate boundary fault zone both underneath the sea and beneath the land.

More information:  Multinational probe of Hikurangi subduction zone gets underway

The course of RV Tangaroa taken during October - November 2017 is shown in the Google map below.

Seismometer deployment grid

The graphic shows planned deployment lines for marine and land seismometers that are a key part of the project. Spacings of the Ocean Bottom Seismometers will be between 10km and 15km. In the more intensive survey area east of Gisborne, spacings will be 2km between instruments. In the on-land part of the project, instruments will be placed on the ground at 2km intervals. All the instruments will record marine seismic pulses from a ship and this will enable scientists to develop cat scan-like images of the Earth’s crust to a depth of about 30km. [Image: GNS Science]