3 years ago by Kate Boersen
A team of scientists from the University of Southern Mississippi and GNS Science have been surveying various field sites along the East Coast looking for evidence of past tsunami and earthquake events.
The lagoons east of Wairoa are known to contain a good archive of old earthquakes and tsunamis but the current focus is on more recent events.
“Finding evidence of large tsunamis and earthquakes that have hit the area pre-historically can help us learn more about what might happen in the future,” says Dr Ursula Cochran from GNS Science.
The scientists initially carry out a visual assessment of sediment layers and, if considered worthwhile, they take a sediment core using a long steel, tubular sediment corer. The corer is pushed as far into the ground as possible; when it can't go any further, it's pulled to the surface and then analysed.
A sediment core taken at Ohuia Lagoon near Wairoa is already of interest to the scientists but before scientists can say for sure whether or not these cores provide evidence of past tsunami events, the sediment needs to be analysed.
“We’ll take these cores back to the lab and look at them under the microscope, and do things like high resolution grain size analysis, palaeontological analysis and geochemical analysis,” says Assistant Professor Jessica Pilarczyk from the University of Southern Mississippi.
While this analysis takes quite a bit of time, it will help provide evidence of past earthquakes and tsunamis. This information can then be used to understand and better plan for future events.
The work is part of a four year US National Science Foundation (NSF) funding research programme called the ‘SHIRE: Seismogenesis at Hikurangi Integrated Research Experiment’ and ties in with a five year NZ Ministry of Business, Innovation and Employment (MBIE) research programme called the ‘Hikurangi Subduction Earthquakes and Slip Behaviour’.
Further field work will be carried out early next year and details of the work and the scientists’ progress will be available through East Coast LAB (Life at the Boundary).