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Saturday, March 30, 2013

Maps of lateral spreading and other earthquake effects in Avonside

Courtesy of a blog reader I have discovered a Tonkin & Taylor report on lateral spread in the Avonside Area. The full title is Appendix M: Avonside study area – lateral spreading. The EQC website is currently closed however you can download it from here.

On the same website, but this page here, is more geotechnical information arising from the Liquefaction Vulnerability Study (mentioned on the blog earlier in the month here). There is a huge range of stuff however, as Avonside is the only suburb for which there are detailed maps, possibly nothing informative for those in other Red Zoned areas.

The report is a collection of maps that show measured changes in height, and ground surface observations of liquefaction, ground cracking and lateral spread throughout Avonside. The time period of the maps is from September 2010 through to at least the June earthquakes in some cases, and December 2011 in others. The report itself is undated.

For those who have some doubts about what happened this is a good set of maps to check what you observed against what was recorded by Tonkin & Taylor. If you are stuck for a place to start try Map 6. This map shows the amount of land movement over the period. The longer the arrow the more movement there was (there is a scale for the arrows at the bottom of the map). If my eye-balling is correct then the land under Cowlishaw Street moved about half a metre and the land under Bracken Street moved well over a metre. Land under Dallington by the Gayhurst Bridge moved close to two metres.

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