Liquefaction Map

What is Liquefaction?

Liquefaction happens when earthquake shaking causes water-saturated soil to temporarily lose strength and behave like a liquid. This can damage buildings and infrastructure.

How do I view Liquefaction Zones on the Map?

To see liquefaction hazards for a Christchurch property:

1. Navigate to the Relab Pro map view
2. Click the Liquefaction Overlay button at the top of the map to see liquefaction zones colour coded on the map
3. Zoom out to view zone classifications (TC1, TC2, etc.) labeled on the colour-coded area

What do the different colors on the liquefaction map mean?

Each colour on the liquefaction map represents a different Technical Category (TC) that indicates the level of liquefaction risk. This is categorised and defined by Christchurch City Council as:

• . TC1 (Light Grey) - "Future land damage from liquefaction is unlikely. Standard foundations can be used for concrete slabs or timber floors".

• TC2 (Yellow) - "Minor to moderate land damage from liquefaction is possible in future significant earthquakes. You can use standard timber piled foundations for houses with lightweight cladding and roofing and suspended timber floors or enhanced concrete foundations".

• TC3 (Blue) - "Moderate to significant land damage from liquefaction is possible in future significant earthquakes. Site-specific geotechnical investigation and specific engineering foundation design is required. Site-specific geotechnical investigation and specific engineering foundation design is required."

• White Zone - Technical Category not applicable. These are non-residential properties in urban areas, properties in rural areas, or properties in hill areas that have not been given a technical category.
• Red Zone - Land that has been severely damaged by earthquakes and is not suitable for rebuilding at present, or areas with unacceptable risk to life safety.

• Damaging liquefaction unlikely (Dark Grey)

• Liquefaction assessment needed (Orange)