HB’s quake story found in sediment
Researchers are collecting clues to piece together an earthquake history for Hawke’s Bay.
Victoria University PhD student Charlotte Pizer is studying sediment in the Pakuratahi Valley to determine when past subduction zone earthquakes and tsunami had occurred.
‘‘We are specifically looking for layers of sediments that may have been disturbed during an earthquake, or shells that have been carried inland by a tsunami, to radiocarbon date,’’ Pizer said.
‘‘Pakuratahi Valley is one of three sites we will be investigating in Hawke’s Bay, and we will be using the evidence we collect here to compare with evidence in sediment cores that have been collected offshore.’’
Hawke’s Bay was a very important place to study due to the nearby Hikurangi subduction zone, Pizer said.
The zone is where the Pacific Plate subducts, or dives beneath, the Australian Plate. Subduction zones can produce large quakes and tsunami as the Hikurangi zone has done in the past.
Pizer said the findings could assist preparation for future quakes. To date, information about the frequency and size of subduction earthquakes was limited.
‘‘We want to increase the precision of this record by integrating offshore and onshore evidence of very large earthquakes and understand the tsunami hazard they pose.’’
In August, researchers would undertake ‘‘sediment coring’’ to break down the outcrops and find evidence of older quakes.
At this stage, the ‘‘relatively young’’ sediment being studied reveals recent earthquakes.
East Coast Life at the Boundary project leader Kate Boersen said the research to refine the Hikurangi subduction earthquake and tsunami record would allow a better assessment of hazards. That included likely impacts and would inform preparation for future earthquakes.
Pizer’s PhD research is a joint project between Victoria University and GNS Science.
It is part of a five-year Ministry of Business, Innovation and Employment (MBIE) research programme, entitled Hikurangi Subduction Earthquakes and Slip Behaviour.