# The model’s map

Not what the ground did, what the study says it would do. The November 2019 Tonkin & Taylor liquefaction vulnerability study graded 600 areas of the district, about 43,269 hectares, under the 2017 national guidance for liquefaction-prone land.

## The record

- 600 assessed areas, ~43,269 ha
- high: 186 (High Liquefaction Vulnerability), 123 flagged for lateral spreading
- medium: 182 (Medium Liquefaction Vulnerability)
- possible: 193 (Liquefaction Damage is Possible), 19 flagged for lateral spreading
- low: 23 (Low Liquefaction Vulnerability)
- unlikely: 16 (Liquefaction Damage is Unlikely)

## The suburbs the model grades worst
Each suburb by its dominant class, the share is the fraction of its outline that grade covers.

- Richmond: 100% of its outline graded high · 13 free-face flags
- Avondale: 94% of its outline graded high · 9 free-face flags
- Edgeware: 85% of its outline graded high · 6 free-face flags
- Dallington: 74% of its outline graded high · 6 free-face flags
- Wainoni: 67% of its outline graded high · 4 free-face flags
- Avonside: 60% of its outline graded high · 9 free-face flags
- Opawa: 52% of its outline graded high · 9 free-face flags
- Burwood: 48% of its outline graded high · 9 free-face flags
- Bexley: 42% of its outline graded high · 7 free-face flags
- North New Brighton: 37% of its outline graded high
- Parklands: 37% of its outline graded high · 1 free-face flag
- Northcote: 100% of its outline graded medium
- Somerfield: 100% of its outline graded medium
- PAPANUI: 97% of its outline graded medium
- Linwood: 96% of its outline graded medium · 2 free-face flags

_Sampled join, a grid of points inside each suburb outline asks which assessed area holds it; the class shares are fractions of the outline and the dominant class is the verdict. A class is the model’s read on a patch of ground, not a finding about an address._

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Christchurch City Council open data, the LiquefactionVulnerability layer of OpenData/LandCharacteristic. A class is the model’s verdict on a patch of ground, not a finding about an address, the study itself calls for site-specific analysis. What the ground actually did in February 2011: https://www.chch.live/liquefaction. A point’s own answer: https://www.chch.live/before. The files: https://www.chch.live/vulnerability.json · https://www.chch.live/vulnerability.geojson · by suburb: https://www.chch.live/suburb-vulnerability.json