2 years ago by Helen Shea
A team of researchers has descended on Hawke’s Bay to study how liquefaction in the 1931 Hawke’s Bay earthquake affected the region to help inform and hopefully improve future liquefaction assessment.
Research of recent New Zealand earthquakes has shown that current liquefaction assessments overestimate the severity of liquefaction impacts in certain soil types and this additional work will add immense value to what is already known.
The work is being conducted by researchers from a number of organisations including Universities of Canterbury, University of Auckland, Tonkin & Taylor, Virginia Tech and University of Texas.
They will use historical New Zealand earthquake information, and have been collecting photos, published accounts and reports from these earthquakes, along with the extensive geotechnical investigation data available in the New Zealand Geotechnical Database (NZGD).
Liam Wotherspoon from the University of Auckland says they have worked through a large collection of historical photos and records and developed a database of locations where liquefaction occurred, and just as importantly, where it did not occur as a result of the Hawke’s Bay 1931 earthquake.
“Photos of building damage often also show the ground surrounding these buildings, and in turn that has shown little or no evidence of liquefaction,” says Dr Wotherspoon.
“The next step is to undertake advanced soil testing at a number of parks, reserves and schools around Napier and Hastings area over the next few weeks. This will enable us to get detailed characteristics of the soil at these locations to help inform our research.”
He says the researchers will be using traditional soil investigation techniques alongside a new investigation method that provides extremely detailed information on the stiffness of the soil, if the soil is saturated or not, and how this changes with depth.
Dr Wotherspoon says all this work forms the first piece of the puzzle. Further testing will also be carried out to assess how much the ground shook in the 1931 earthquake and how deep the groundwater was at the time.
“By combining all these pieces we can finalise quality case histories and ultimately improve the accuracy of liquefaction assessment procedures.
The project is part of the QuakeCoRE centre of research excellence in earthquake resilience, a project partner of East Coast LAB.