Note: this guideline is issued by the Surveyor-General under section 7(1)(ga) of the Cadastral Survey Act 2002 about the Rules for Cadastral Survey 2010 and is not legally binding.

The following information relates to rule 20.4 and the requirements that redefined affected boundaries must reflect earthquake movement, be referenced by witness marks and permanent reference marks, and the survey connected to an official datum.

Redefined affected boundary must reflect earthquake movement

Some affected boundaries may have changed orientation, been extended, compressed or changed shape (distorted) as a result of earthquake movement.  When defining by survey, examples of redefining in terms of earthquake movement include the creation of new boundary points, new angles, arcs or bends in the case of an existing right line boundary, new bends in an irregular or water boundary, or showing a difference in the shape of a permanent structure boundary.  In the following diagrams the:

  • pecked black line represents the boundary accuracy tolerance where each accuracy tolerance formula between boundary points is made up by a ‘constant’ plus a ‘distance factor’ (refer to rule 3.3.1),

  • pecked blue line represents the boundary in its pre-earthquake boundary location,

  • solid blue line  represents the old boundary in its post-earthquake boundary location.

Diagram showing affected boundary change


  • The diagram below illustrates where the bend in the alignment of a right-line boundary is less than the accuracy tolerances which means it is not an affected boundary.  In this example the pre-earthquake dimensions have been retained.
  • The diagram below illustrates an affected boundary where the surveyor has addressed the issue by creating a new boundary angle to reflect the impact of the earthquake movement on the boundary.
  • The diagram below illustrates where the surveyor has redefined an affected boundary to take into account stretching and rotation of the pre-earthquake boundary caused by movement of the old boundary mark at the eastern end of the boundary.  The movement of an old boundary point outside accuracy tolerances will also affect other boundaries that connect to that point.  This is illustrated by the change in shape and location of the two eastern boundaries that ran north and south of the original boundary position.  

Orientation and connection

Rule 20.4(b) requires a redefined boundary on a primary parcel, stratum boundary or a lease parcel that is not a permanent structure boundary, to be orientated in terms of an official datum [r 20.4(b)(i)], connected to a datum in specific cases [r 20.4(b)(ii)] and referenced by witness marks and PRMs [r 20.4(b)(iii) – (v)].


Rule 20.4(b)(iii) requires a boundary point to be witnessed as if this was a requirement set out in rule 7.3.1.  This means principal rules that normally apply as a result of rule 7.3.1 being applied, also apply (including rules 7.3.2 – 7.3.4 (Witnessing of boundary points), r 7.4 (Permanent marks), r 7.5 Unique survey mark names), r 8 (Cadastral Survey Datasets), r 9 (CSD Plan) and r 12 (Diagram plan symbols and text)).

The reduced witness mark requirements for a boundary reinstatement survey or a Monumentation CSD set out in rules 7.3.2(d) and 11.2 cannot be used [rule 20.4(b)(iv)]. 

Use of monumentation CSDs

Where a survey redefines an affected boundary or associated boundary point a monumentation CSD must not be used [rule 20.4(c)]. This is important to note particularly where just a single boundary point is being redefined. 

Last Updated: 21 April 2017
Authority: Surveyor-General - Section 7(1)(ga) of the Cadastral Survey Act 2002
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