chch.live the moved ground

The ground that moved

After each of the two big shakes the surveyors flew the city and drew every patch where the ground failed, 7,382 mapped patches, about 16,933 hectares of the city’s footprint, most of it under the eastern river suburbs. This is the record of what the ground did, not a model of what it might do.

Mapped patches
7,382
Mapped ground
16,933 ha
February 2011
4,305
September 2010
3,077

February’s footprint, by suburb

Addington, 13.3% of its outline mapped liquefiedAidanfield, 18.1% of its outline mapped liquefiedAkaroa: nothing mappedAranui, 82.1% of its outline mapped liquefiedAvondale, 66.7% of its outline mapped liquefiedAvonhead, 0.2% of its outline mapped liquefiedAvonside, 69.4% of its outline mapped liquefiedBeckenham, 27.8% of its outline mapped liquefiedBelfast, 7.0% of its outline mapped liquefiedBexley, 27.7% of its outline mapped liquefiedBishopdale, 8.1% of its outline mapped liquefiedBottle Lake, 10.5% of its outline mapped liquefiedBromley, 78.2% of its outline mapped liquefiedBrooklands, 45.8% of its outline mapped liquefiedBroomfield: nothing mappedBryndwr, 18.8% of its outline mapped liquefiedBurnside, 1.8% of its outline mapped liquefiedBurwood, 51.4% of its outline mapped liquefiedCasebrook, 7.4% of its outline mapped liquefiedCashmere, 1.9% of its outline mapped liquefiedCass Bay: nothing mappedChristchurch Airport: nothing mappedChristchurch Central, 47.3% of its outline mapped liquefiedClifton: nothing mappedCorsair Bay: nothing mappedCoutts Island, 8.6% of its outline mapped liquefiedCracroft, 0.8% of its outline mapped liquefiedDallington, 61.4% of its outline mapped liquefiedDiamond Harbour: nothing mappedDuvauchelle: nothing mappedEdgeware, 81.7% of its outline mapped liquefiedFendalton, 44.6% of its outline mapped liquefiedFerrymead, 44.9% of its outline mapped liquefiedGovernors Bay, 0.1% of its outline mapped liquefiedHalswell, 12.3% of its outline mapped liquefiedHarewood, 0.9% of its outline mapped liquefiedHeathcote Valley, 1.5% of its outline mapped liquefiedHei Hei: nothing mappedHillmorton, 9.7% of its outline mapped liquefiedHillsborough, 9.2% of its outline mapped liquefiedHoon Hay, 29.6% of its outline mapped liquefiedHornby: nothing mappedHornby South, 0.0% of its outline mapped liquefiedHuntsbury, 1.8% of its outline mapped liquefiedIlam, 1.8% of its outline mapped liquefiedIslington, 0.1% of its outline mapped liquefiedKainga, 4.5% of its outline mapped liquefiedKennedys Bush, 5.7% of its outline mapped liquefiedLe Bons Bay: nothing mappedLinwood, 41.7% of its outline mapped liquefiedLittle River, 0.0% of its outline mapped liquefiedLyttelton, 1.6% of its outline mapped liquefiedMairehau, 28.5% of its outline mapped liquefiedMarshland, 11.8% of its outline mapped liquefiedMcLeans Island, 0.0% of its outline mapped liquefiedMerivale, 48.6% of its outline mapped liquefiedMiddleton: nothing mappedMoncks Bay, 0.3% of its outline mapped liquefiedMount Pleasant, 2.6% of its outline mapped liquefiedNew Brighton, 32.6% of its outline mapped liquefiedNorth New Brighton, 54.7% of its outline mapped liquefiedNorthcote, 0.0% of its outline mapped liquefiedNorthwood, 4.5% of its outline mapped liquefiedOkains Bay: nothing mappedOpawa, 38.6% of its outline mapped liquefiedOuruhia, 18.5% of its outline mapped liquefiedPapanui, 11.8% of its outline mapped liquefiedParklands, 37.8% of its outline mapped liquefiedPhillipstown, 58.7% of its outline mapped liquefiedPigeon Bay: nothing mappedPort Levy: nothing mappedPrebbleton, 0.1% of its outline mapped liquefiedRedcliffs, 14.6% of its outline mapped liquefiedRedwood, 3.4% of its outline mapped liquefiedRiccarton, 8.5% of its outline mapped liquefiedRichmond, 79.0% of its outline mapped liquefiedRichmond Hill: nothing mappedRolleston: nothing mappedRussley, 0.1% of its outline mapped liquefiedSaint Albans, 56.3% of its outline mapped liquefiedSaint Martins, 47.8% of its outline mapped liquefiedScarborough: nothing mappedShirley, 45.5% of its outline mapped liquefiedSockburn: nothing mappedSomerfield, 39.3% of its outline mapped liquefiedSouth New Brighton, 16.4% of its outline mapped liquefiedSouthshore, 36.1% of its outline mapped liquefiedSpencerville, 12.9% of its outline mapped liquefiedSpreydon, 41.7% of its outline mapped liquefiedStrowan, 33.7% of its outline mapped liquefiedSumner, 0.1% of its outline mapped liquefiedSydenham, 39.4% of its outline mapped liquefiedTai Tapu, 0.8% of its outline mapped liquefiedTe Onepoto Taylors Mistake: nothing mappedTempleton, 0.0% of its outline mapped liquefiedUpper Riccarton: nothing mappedWaimairi Beach, 2.4% of its outline mapped liquefiedWainoni, 84.9% of its outline mapped liquefiedWainui: nothing mappedWaltham, 51.9% of its outline mapped liquefiedWestmorland, 9.3% of its outline mapped liquefiedWigram, 0.1% of its outline mapped liquefiedWoolston, 62.9% of its outline mapped liquefiedYaldhurst, 0.0% of its outline mapped liquefied

a quarter or more of the outline a tenth some a trace none mapped

Each suburb shaded by the share of its outline under mapped February 2011 liquefaction, a patch files under the suburb its middle crosses. 82 suburbs hold mapped ground; the rest are not absent so much as unmarked, the survey only drew what it could see from the air and visit on the ground.

The suburbs, wettest first

Bromley 78.2% of its outline · 603 ha in February · 29 ha in September · 69 patches Woolston 62.9% of its outline · 345 ha in February · 0 ha in September · 155 patches Brooklands 45.8% of its outline · 336 ha in February · 278 ha in September · 108 patches Christchurch Central 47.3% of its outline · 303 ha in February · 86 ha in September · 222 patches Burwood 51.4% of its outline · 302 ha in February · 171 ha in September · 175 patches Halswell 12.3% of its outline · 281 ha in February · 735 ha in September · 421 patches Saint Albans 56.3% of its outline · 224 ha in February · 50 ha in September · 205 patches Parklands 37.8% of its outline · 213 ha in February · 23 ha in September · 127 patches Aranui 82.1% of its outline · 185 ha in February · 14 ha in September · 64 patches Avondale 66.7% of its outline · 144 ha in February · 150 ha in September · 61 patches Richmond 79.0% of its outline · 141 ha in February · 42 ha in September · 69 patches Ouruhia 18.5% of its outline · 139 ha in February · 140 ha in September · 96 patches New Brighton 32.6% of its outline · 133 ha in February · 76 ha in September · 70 patches Bottle Lake 10.5% of its outline · 131 ha in February · 57 ha in September · 121 patches Mairehau 28.5% of its outline · 129 ha in February · 21 ha in September · 118 patches Shirley 45.5% of its outline · 125 ha in February · 42 ha in September · 61 patches Wainoni 84.9% of its outline · 122 ha in February · 40 ha in September · 28 patches Sydenham 39.4% of its outline · 120 ha in February · 1 ha in September · 108 patches Linwood 41.7% of its outline · 118 ha in February · 28 ha in September · 84 patches Hoon Hay 29.6% of its outline · 114 ha in February · 13 ha in September · 122 patches Ferrymead 44.9% of its outline · 111 ha in February · 8 ha in September · 23 patches Spreydon 41.7% of its outline · 110 ha in February · 0 ha in September · 74 patches North New Brighton 54.7% of its outline · 109 ha in February · 1 ha in September · 28 patches Marshland 11.8% of its outline · 103 ha in February · 4 ha in September · 100 patches Coutts Island 8.6% of its outline · 103 ha in February · 154 ha in September · 106 patches Merivale 48.6% of its outline · 101 ha in February · 54 ha in September · 111 patches Somerfield 39.3% of its outline · 97 ha in February · 0 ha in September · 100 patches Waltham 51.9% of its outline · 92 ha in February · 0 ha in September · 64 patches Fendalton 44.6% of its outline · 88 ha in February · 57 ha in September · 97 patches Kennedys Bush 5.7% of its outline · 84 ha in February · 133 ha in September · 79 patches Avonside 69.4% of its outline · 84 ha in February · 94 ha in September · 53 patches Dallington 61.4% of its outline · 82 ha in February · 248 ha in September · 35 patches Edgeware 81.7% of its outline · 79 ha in February · 218 ha in September · 60 patches Phillipstown 58.7% of its outline · 73 ha in February · 0 ha in September · 34 patches Belfast 7.0% of its outline · 71 ha in February · 108 ha in September · 215 patches Hillsborough 9.2% of its outline · 62 ha in February · 0 ha in September · 45 patches Bexley 27.7% of its outline · 60 ha in February · 188 ha in September · 52 patches Saint Martins 47.8% of its outline · 55 ha in February · 0 ha in September · 30 patches Strowan 33.7% of its outline · 46 ha in February · 10 ha in September · 49 patches Bryndwr 18.8% of its outline · 40 ha in February · 1 ha in September · 50 patches

Questions, answered briefly

How much of Christchurch liquefied in the earthquakes?

The surveys drew 7,382 mapped patches, about 16,933 hectares of the city’s footprint, where the ground failed across September 2010 and February 2011. The footprints overlap but differ: ground that moved in one shake did not always move in the other.

Which suburbs had the most liquefaction?

Bromley tops the roll, the survey drew about 603 hectares of mapped ground inside its outline. The eastern river suburbs carry the record: the ground that was wet first is the ground that moved.

Does a mapped patch mean my house was damaged?

No, a patch is the survey’s footprint of an effect seen from the air and on the ground, not a finding about any one address. The per-address answer lives at /before; this page counts the patches, not the claims.

Where does this record come from?

Environment Canterbury’s open layers, the post-quake mapping GNS and ECan made from aerial imagery and site visits after each shake. A patch marked "probable" or "possible" is the survey’s own certainty, kept verbatim; patches the surveyors could not call are dropped, not guessed.

Also in the earthquakes

The record behind this

Environment Canterbury’s open liquefaction layers, the mapping GNS and ECan made from aerial imagery and site visits after September 2010 and February 2011. A patch is a footprint of an effect the survey could see, kept with the survey’s own certainty; patches it could not call are dropped, not guessed. A patch is not a finding about any one address, the point answer lives at /before.

This page as markdown: /liquefaction.md · the patches as data: /liquefaction.geojson · /liquefaction.json · the story: why the east liquefied · the shakes that did it: /sequence · the faults under it: /faults · what the Crown drew over it: /redzone · what the ground was graded: /technical-categories · what the model expects: /vulnerability · every roll, counted: /geography.