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Liquefaction clues sought from 1931 quake

NZ Newswire logoNZ Newswire 1/05/2017

An international team of researchers is looking to the 1931 Hawke's Bay earthquake to provide clues to help improve liquefaction assessment.

Research of recent New Zealand earthquakes has shown that current assessments overestimate the severity of liquefaction impact in certain soil types, Auckland University senior lecturer Dr Liam Wotherspoon says.

The team in Hawke's Bay come from Canterbury University, Auckland University, engineering consultancy Tonkin and Taylor, Virginia Tech and Texas University.

The researchers are using historical information, and have been collecting photos, published accounts, reports and data available in the New Zealand Geotechnical Database (NZGD).

Dr Wotherspoon says they have developed a database of locations where liquefaction occurred, and didn't occur, as a result of the quake, which killed 256 people and devastated the region.

"Photos of building damage often also show the ground surrounding these buildings, and in turn that has shown little or no evidence of liquefaction," he said.

The next step is doing advanced testing at a number of parks, reserves and schools around Napier and Hastings to get detailed characteristics of the soil there.

Researchers will use traditional soil investigation techniques alongside a new method that provides detailed information on the stiffness of the soil, if the soil is saturated or not, and how this changes with depth.

Dr Wotherspoon said all this work was the first piece in the puzzle.

Further testing would also be carried out to assess how much the ground shook and how deep the groundwater was at the time.

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