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Images, UC QuakeStudies

Photograph captioned by BeckerFraserPhotos, "Blue Lagoon Drive in Brooklands. The whole of this street is red zoned land. Some of the homeowners are unhappy with the land zoning as they believe that their area has much less impact from liquefaction than other red zoned areas. Some of the street lights are leaning, but the road seems in very good condition for a red zoned street and there is little evidence of liquefaction. Most red zoned streets have none of their original surface left, and the liquefaction is evident on all the verges and gardens".

Images, UC QuakeStudies

Dried liquefaction silt in North New Brighton. The photographer comments, "This is the result of liquefaction which spewed out after the double earthquake in Christchurch. Having flowed into a shallow depression that was deep enough for a fair quantity of the silty liquid to settle and separate: the heavy sand below and a talcum powder like substance on top. Some of these are so delicate that a mouse crossing them would probably crack them. Here the sun has dried them out and they have contracted and curled up towards their centres".

Research papers, University of Canterbury Library

Earthquake-triggered soil liquefaction caused extensive damage and heavy economic losses in Christchurch during the 2010-2011 Canterbury earthquakes. The most severe manifestations of liquefaction were associated with the presence of natural deposits of clean sands and silty sands of fluvial origin. However, liquefaction resistance of fines-containing sands is commonly inferred from empirical relationships based on clean sands (i.e. sands with less than 5% fines). Hence, existing evaluation methods have poor accuracy when applied to silty sands. The liquefaction behaviour of Christchurch fines-containing (silty) sands is investigated through a series of Direct Simple Shear (DSS) tests. This type of test better resembles earthquake loading conditions in soil deposits compared to cyclic triaxial tests. Soil specimens are reconstituted in the laboratory with the water sedimentation technique. This preparation method yields soil fabrics similar to those encountered in fluvial soil deposits, which are common in the Christchurch area. Test results provide preliminary indications on how void ratio, relative density, preparation method and fines content influence the cyclic liquefaction behaviour of sand-silt mixtures depending on the properties of host sand and silt.

Images, UC QuakeStudies

People walking amongst silt in Hagley Park shortly after the 22 February 2011 earthquake. These silt deposits were caused by the soil liquefying during the 22 February 2011 earthquake. The water flowed out, bringing sand with it.