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]( http://data.linz.govt.nz/layer/1589 ).**

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]( http://www.linz.govt.nz/survey-titles/canterbury-earthquake/canterbury-earthquake/geodetic-survey-control-coordinates ) on the LINZ website.**