Scientists say sea shells should shed substantial light on seismic situation

Friday, 13 March 2020

The 90 metre long trench dug by scientists looking for evidence of past earthquakes at Aramoana, Hawke's Bay.

Sea shells being recovered from a 90-metre-long trench at a Hawke's Bay beach should shed light on past earthquakes and tsunami.

GNS scientists have dug the trench at Aramoana, southern Hawke's Bay, because it's a site that has been uplifted in a series of large earthquakes.

Over the last 8000 years the earthquakes have created three marine terraces. The terraces usually provide good evidence to date past earthquakes.

'We are specifically looking for shells that we can later radiocarbon-date in the lab to try and pinpoint the timing of past earthquakes and tsunami,' says project leader Dr Nicola Litchfield.

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'If we identify evidence for an earthquake at only one location, then it is likely this event occurred on near-shore faults, which will have uplifted and shaken a relatively small area.

'But if we identify evidence at multiple sites, that points to a Hikurangi subduction zone earthquake.'

Scientists have known for a long time that the East Coast has experienced a number of large earthquakes in the past but are still trying to figure out how big and how often these events occurred.

The research is part of a five-year Ministry of Business, Innovation and Employment research programme called Hikurangi Subduction Earthquakes and Slip Behaviour.

It should help develop further understanding of the earthquake and tsunami risk along the East Coast.