Christchurch earthquake land damage background

By Grant Jacobs 24/06/2011

Before starting, I should apologise to readers for bringing so little of late, being swamped with work…[1]

The latest news on the Christchurch earthquake has been the announcement of a relief package for some of the worst affected suburbs in Christchurch from the September 4th, 2010, February 22nd, 2011, June 13th, 2011 (and other aftershocks) target an initial ‘red zone’ (large PDF map) of properties with badly damaged land, rather than damaged buildings as such.

Here I’ve gathered a few background items available on-line that might interest readers. (I’m not a geologist; I’m offering this loose collection of a video, brochure and a presentation (summary report) of the survey work in lieu of something more substantial from a geologist in the meantime.)

As this video below explains this land needs to be cleared before it could be made suitable for building upon again. (Assuming that will be done – many residents have expressed a wish for this to be riverside reserve land.)

This video presents a little of the land damage issues and shows two maps of areas of liquefaction, from the September and February earthquakes. Comparing the two shows a dramatic difference in liquefaction from the February earthquake compared to the September event. Towards the end they illustrate how the some ground was not able to support the foundations of a house with shots of a house that has sunken into the soil.

While gathering material for this post, I encountered (again) a large PDF for a brochure on liquefaction from ECAN’s Q-Files page (see this PDF file).

A report presented at the Ninth Pacific Conference on Earthquake Engineering in April is also available on-line (PDF file). Given this is a technical report, it offers a reasonably clear explanation of the surveying that has been done. The schematic below has been taken from this presentation:



I’m not a geologist!

[1] This madness should end sometime in early July, whereupon I’ll be seeking new contracts again. And so on the cycle goes…

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