New Zealand Geodetic Data

The New Zealand Quasigeoid2009 (NZGeoid2009) can be used to convert GPS derived ellipsoidal heights to New Zealand Vertical Datum 2009 (NZVD2009) normal-orthometric heights that relate more closely to mean sea level and the local gravity field. NZGeoid2009 can also be used to transform heights to any of the 13 official local vertical datums used across New Zealand, more information on this transformation is available at www.linz.govt.nz/geodetic/conversion-coordinates/h....

NZGeoid2009 is formally defined in the LINZ standard LINZS25004 which can be obtained from www.linz.govt.nz/geodetic/standards-publications/s.... NZGeoid2009 models the difference between the GRS80 ellipsoid and the geoid over the New Zealand region. The geoid is a theoretical surface of equal gravity that roughly approximates the mean level of the sea across the Earth.

NZGeoid2009 is published by LINZ and was computed by enhancing the EGM2008 global gravity model with terrestrial gravity observations over New Zealand and DNSC08 satellite altimetry data over the oceans. The model is published on a one arc-minute grid covering New Zealand's extended exclusive economic zone.

The accuracy of NZGeoid2009 is nominally ±0.08 metres across New Zealand. More information on the accuracy in relation to the 13 local vertical datums is provided in LINZS25004.

The Canterbury region of New Zealand experienced a sequence of significant earthquakes during 2010 and 2011. These earthquakes occurred on 2010-09-04, 2011-02-22, 2011-06-13 and 2011-12-23. This layer contains coordinates computed from GNSS fast static and network RTK surveys undertaken after the Canterbury earthquakes. It also includes Lyttelton Vertical Datum 1937 and Christchurch Drainage Datum heights, derived from the GNSS data.

Users may also be interested in the simplified data in the companion layer Canterbury Earthquake Geodetic Marks (2010, 2011) - Simple.

These coordinates are only provisional. Analysis is ongoing as further data is collected. Coordinates were calculated using SNAP v2.3.61. Stations were constrained using coordinates calculated by GNS Science. Some coordinates were calculated from data provided by Christchurch City Council and other public and private organisations. No precise levelling data has been used.

The uncertainty (one standard deviation) is 0.02m horizontally, and 0.03m vertically for NZGD2000 ellipsoidal heights. The uncertainty (one standard deviation) of the Lyttelton Vertical Datum 1937 and Christchurch Drainage Datum heights is 0.05m.

The coordinates calculated prior to 2010-09-04 have been calculated from a combined adjustment including LINZ data and additional data provided by public and private organisations. These coordinates differ from those in the Geodetic Database and more accurately reflect the position of the mark immediately prior to the 2010-09-04 earthquake.

The deformation model igns2011_working.grd calculated from a model (v4) provided by GNS Science on 28 April 2011 was used to remove secular deformation.

Lyttelton Vertical Datum 1937 heights have been computed from NZGD2000 ellipsoidal heights by subtracting NZGeoid2009 geoid heights and adding an offset of 0.47m to bring in terms of Lyttelton Vertical Datum 1937. Christchurch Drainage Datum (CDD) heights have been computed in the Christchurch area from NZGD2000 ellipsoidal heights by subtracting NZGeoid2009 geoid heights and adding an offset of 0.523m (specifically calculated for Christchurch City) to bring in terms of Lyttelton Vertical Datum 1937 (for Christchurch) and a further offset of 9.04m to bring in terms of CDD.

The model used to estimate whether movements greater than 2cm occurred at a mark (excluding those due to liquefaction or other localised deformation) after the 2010-09-04 earthquake was provided by GNS Science (Darfield_Sep2010_model_8.5_grid_displacements_calcs.xls). The model used to estimate whether movements greater than 2cm occurred at a mark (excluding those due to liquefaction or other localised deformation) after the 2011-02-22 earthquake was provided by GNS Science (Chch_Feb2011_geodetic_source_model_3.21.xls). The model used to estimate whether movements greater than 2cm occurred at a mark (excluding those due to liquefaction or other localised deformation) after the 2011-06-13 earthquake was provided by GNS Science (Chch_Jun2011_geodetic_source_model_0.4.xls). The model used to estimate whether movements greater than 2cm occurred at a mark (excluding those due to liquefaction or other localised deformation) after the 2011-12-23 earthquake was provided by GNS Science (Chch_Dec2011_geodetic_source_model_0.2.xls).

These coordinates are suitable for use in surveys and other geospatial activities in Canterbury and Christchurch.

For full information about this dataset, see the Canterbury earthquake information on the LINZ website.

The Canterbury region of New Zealand experienced a sequence of significant earthquakes during 2010 and 2011. These earthquakes occurred on 2010-09-04, 2011-02-22, 2011-06-13 and 2011-12-23. The coordinates in this layer account for all significant movements relating to these, so should be consistent with any observations made after the last earthquake to affect a given area (neglecting localised deformation such as that due to liquefaction).

Users may also be interested in the more comprehensive data in the companion layer Canterbury Earthquake Geodetic Marks (2010, 2011) - Comprehensive.

These coordinates are only provisional. Analysis is ongoing as further data is collected. Coordinates were calculated using SNAP v2.3.61. Stations were constrained using coordinates calculated by GNS Science. Some coordinates were calculated from data provided by Christchurch City Council. No precise levelling data has been used.

The estimated accuracy is 0.02m horizontally and 0.03m vertically.

The deformation model igns2011_working.grd calculated from a model (v4) provided by GNS Science on 28 April 2011 was used to remove secular deformation.

These coordinates are suitable for use in surveys and other geospatial activities in Canterbury and Christchurch.

For further information about this dataset, see the Canterbury earthquake information on the LINZ website.

The deformation model associated with the NZGD2000 datum was updated, nominally at 1 August 2013. The actual update of LINZ data took place on 14-15 December 2013. This update involved reverse patches, which means that the "reference coordinates" of features were updated. The main updates relate to the Christchurch earthquakes. The patch also updated coordinates affected by other South Island earthquakes since 2000.

These updates have been incorporated into Landonline and resulted in spatial updates to all features in the affected areas.

This data set contains contours indicating the extent and magnitude of the coordinate changes to assist in assessing the impact of this update on client data sets. This dataset is also available as a multipolygon.

For more information see here

The deformation model associated with the NZGD2000 datum was updated, nominally at 1 August 2013. The actual update of LINZ data took place on 14-15 December 2013. This update involved reverse patches, which means that the "reference coordinates" of features were updated. The main updates relate to the Christchurch earthquakes. The patch also updated coordinates affected by other South Island earthquakes since 2000.

These updates have been incorporated into Landonline and resulted in spatial updates to all features in the affected areas.

This data set contains contours indicating the extent and magnitude of the coordinate changes to assist in assessing the impact of this update on client data sets. This dataset is also available as a polyline.

For more information see here

The Canterbury region of New Zealand experienced a sequence of significant earthquakes during 2010 and 2011. These earthquakes occurred on 2010-09-04, 2011-02-22, 2011-06-13 and 2011-12-23. Precise-levelling surveys have been carried out throughout Canterbury and Christchurch to re-establish heights after these earthquakes.

Users may also be interested in the horizontal coordinates derived from GNSS data in the companion layers Canterbury Earthquake Geodetic Marks (2010, 2011) - Comprehensive and Canterbury Earthquake Geodetic Marks (2010, 2011) - Simple

Horizontal Accuracy (standard deviation) approx 1m.
Vertical Accuracy of Lyttelton Vertical Datum 1937 heights (standard deviation) 0.005m.

Heights generated from precise levelling data undertaken to a misclose standard (mm) of 5*sqrt(k) where k is the distance in kilometres. Precise levelling in the Christchurch area was undertaken after the 23 December 2011 earthquake. Other areas were levelled after the most recent earthquake to have affected heights in that area. Heights therefore represent the position of marks accounting for all four substantial Canterbury earthquakes.

These heights are only provisional. Analysis is ongoing as further data is collected.
Heights calculated using SNAP v2.3.64.
Heights were constrained using the pre-earthquake heights at geodetic codes AC9B, AFAQ, AG32 and B853. GNSS observations and modelling indicates that the height change of these marks was negligible.
Some heights were calculated from precise levelling data provided by Christchurch City Council.

These coordinates are suitable for use in surveys and other geospatial activities in Canterbury and Christchurch.

For further information about this dataset, see the Canterbury earthquake information on the LINZ website.

Coordinates computed from surveys undertaken after the 14 February 2016 Canterbury earthquake. These should be consistent with any observations made after this earthquake (neglecting any localised deformation such as that due to liquefaction).

For further information about this dataset, see the Canterbury earthquake information.

These coordinates are only provisional. Analysis is ongoing as further data is collected. Coordinates were calculated using SNAP v2.5.33. Stations were constrained using coordinates of distant PositioNZ continuous GNSS stations that were unaffected by the earthquake.

The standard deviations of coordinates are 0.01m horizontally and 0.02m vertically, relative to the PositioNZ network.

Coordinate changes due to the earthquake have been calculated by comparing pre and post-earthquake coordinates. Pre-earthquake coordinates were calculated relative to public and private continuous GNSS stations. These continuous GNSS stations had data processed for several days early in 2016 (before the earthquake). Other pre-earthquake geodetic data was then readjusted with the continuous GNSS data. Note that this means these coordinate changes may differ slightly from those that would be calculated by comparing the post-earthquake coordinates with those currently in the Geodetic Database.

These coordinates are suitable for use in surveys and other geospatial activities in Canterbury and Christchurch.

The AUK46-NZGD2000 grid enables the conversion of normal-orthometric heights from the Auckland 1946 local vertical datum directly to New Zealand Geodetic Datum 2000 (NZGD2000) ellipsoidal heights.

AUK46-NZGD2000 is published on a one arc-minute grid (approximately 1.8 kilometres) extending over the benchmarks that nominally define the extent of the Auckland 1946 vertical datum (174.0° E to 176.2° E, 36.1° S to 38.0° S).

The conversion value is represented by the attribute “delta”, in metres.

This grid is a combination of New Zealand Quasigeoid 2016 NZGeoid2016 and the AUK46-NZVD2016 height conversion grid. Where NZGeoid2016 is the reference surface for the New Zealand Vertical Datum 2016 (NZVD2016), while the AUK46-NZVD2016 grid models the difference between the Auckland 1946 vertical datum and NZVD2016 using the LINZ GPS-levelling marks.

More information on converting heights between vertical datums can be found on the LINZ website.