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Images for liquefaction silt; more images...

Images, UC QuakeStudies

A large hole surrounded by liquefaction silt in the garden of a house in Bexley. The photographer comments, "This was most probably the serious hole I saw today. Can you imagine that when this occurred the whole area would have been inches deep in brown water. You would not been able to tell what you were walking on. Back in February a little girl rode her bike into one of these and had to be rescued by a passer by".

Images, UC QuakeStudies

Workers use a large water-blasting pipe to clear blocked drains. The photographer comments, "The Australian company Barry Bros Turned up very late at night to clean out our street drains of liquefaction".

Images, UC QuakeStudies

Liquefaction and buckled tarmac on a residential street in North New Brighton. The photographer comments, "In the February 2011 earthquake in Christchurch the kerb at the end of my road was pushed from both ends. This caused it to move away from the grass verge and push itself under the tarmac. The tarmac would normally have been 3 inches below the top of the kerb. Between the kerb and the grass can be seen the colour of the liquefaction that spewed out from the ground. The tarmac in the area seemed to flow downhill".

Images, UC QuakeStudies

Damage to New Brighton Road. The photographer comments, "Would you believe that the up and down dirt track on the right is actually a main road?".

Images, UC QuakeStudies

A large crack between the road and a concrete slab in New Brighton. The photographer comments, "This is the gap that has been growing during all the Christchurch earthquakes. It is between Robbie's Restaurant and the car park in New Brighton".

Research papers, University of Canterbury Library

On February 22, 2011, a magnitude Mw 6.2 earthquake affected the Canterbury region, New Zealand, resulting in many fatalities. Liquefaction occurred across many areas, visible on the surface as ‘‘sand volcanoes’’, blisters and subsidence, causing significant damage to buildings, land and infrastructure. Liquefaction occurred at a number of sites across the Christchurch Boys High School sports grounds; one area in particular contained a piston ground failure and an adjacent silt volcano. Here, as part of a class project, we apply near-surface geophysics to image these two liquefaction features and determine whether they share a subsurface connection. Hand auger results enable correlation of the geophysical responses with the subsurface stratigraphy. The survey results suggest that there is a subsurface link, likely via a paleo-stream channel. The anomalous responses of the horizontal loop electromagnetic survey and electrical resistivity imaging highlight the disruption of the subsurface electrical properties beneath and between the two liquefaction features. The vertical magnetic gradient may also show a subtle anomalous response in this area, however the results are inconclusive. The ground penetrating radar survey shows disruption of the subsurface stratigraphy beneath the liquefaction features, in particular sediment mounding beneath the silt ejection (‘‘silt volcano’’) and stratigraphic disruption beneath the piston failure. The results indicate how near-surface geophysics allow the characteristics of liquefaction in the subsurface to be better understood, which could aid remediation work following liquefaction-induced land damage and guide interpretation of geophysical surveys of paleoliquefaction features.

Images, UC QuakeStudies

The road, driveway and footpath are covered in silt from liquefaction on Papanui Road. In the background is the Christchurch Chinese Methodist Church, which has had its spire removed so restoration work can be carried out.