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Searching for past earthquakes

3 years ago by Kate Boersen

tangaroa credit dave allen NIWA2

A team of scientists conducted a research survey in November 2016 aboard NIWA’s research vessel, Tangaroa, looking for evidence of past earthquakes off the east coast of the North Island.

The scientists were looking for geological evidence of strong ground shaking to try to reconstruct where and when earthquakes have occurred along the Hikurangi plate boundary, New Zealand’s largest earthquake and tsunami hazard.

“We were looking for marine ‘turbidites’, layers of mud, sand and gravel sediment, which settle as a result of seafloor landslides triggered by earthquakes” says NIWA marine geologist and voyage leader Dr Philip Barnes.

The scientists surveyed more than 50 sites between Cook Strait and Poverty Bay despite occasional rough seas, and collected sediment cores up to six metres long.

When the cores were brought back to the surface on board the vessel, they were measured and cut into sections to be photographed, X-rayed, logged and packaged for further analysis.

“This analysis will be tackled as part of a five year project. When completed, it will help assess the hazard, risk and, ultimately, potential losses due to large earthquakes on the Hikurangi plate boundary,” says Barnes.

The work involves scientists from various national research institutions (including NIWA, GNS Science, University of Auckland, University of Otago, University of Canterbury, and Victoria University of Wellington), as well as international researchers from the USA, Turkey, and France.

The research is part of a five year NZ Ministry of Business, Innovation and Employment (MBIE) research programme called ‘Hikurangi Subduction Earthquakes and Slip Behaviour’ and a multi-year  NIWA-MBIE Core Coasts & Oceans Programme Marine Physical Processes and Resources.

Details of further work being carried out as part of these research programmes will be available through East Coast LAB (Life at the Boundary).