Important notice

This data was prepared and/or compiled for the Earthquake Commission (EQC) to assist in assessing insurance claims made under the Earthquake Commission Act 1993. It was not intended for any other purpose. EQC and its engineers, Tonkin & Taylor, have no liability to any user of this data or for the consequences of any person relying on them in any way. Canterbury Geotechnical Database (https://canterburygeotechnicaldatabase.projectorbit.com) data is made available solely on the basis that:

Any database user has read and agrees to the terms of use of the database;
Any database user has read any explanatory text accompanying this map;
The "Important notice" in the following box must be reproduced in a prominent location with an appropriate substitution to the red bracketed text (i.e. within the []) wherever the data or any derivative figures or tables are reproduced.

Important notice

[Figures X, Y and Z were] created from data extracted from the Canterbury Geotechnical Database (https://canterburygeotechnicaldatabase.projectorbit.com), which was prepared for the Earthquake Commission (EQC) to assist in assessing insurance claims made under the Earthquake Commission Act 1993. The data was not intended for any other purpose. EQC and its engineers, Tonkin & Taylor, have no liability for any use of the data or for the consequences of any person relying on it in any way. This "Important notice" must be reproduced wherever [those three figures] or any derivatives are reproduced.

Grid Data

The following Geo TIFF images provide the source data for the "EQC LiDAR and digital elevation models" and "EQC Vertical Ground Movements" map layers. These grids of surface elevations have a 5 m cell size and an origin point of 2.5 mE, 2.5 mN (NZTM2000). The elevations are relative to Lyttelton Vertical Datum 1937 (MSL).

DEM	Source LiDAR	Geo TIFF	Size	Commissioning Agencies
Pre-Earthquake	AAM, 6-9 Jul 2003*	Geo TIFF	73 MB	Christchurch City Council
	AAM, 21-24 Jul 2005	Geo TIFF	39 MB	Environment Canterbury & Waimakariri District Council
	AAM, 6-11 Feb 2008	Geo TIFF	60 MB	Environment Canterbury & Selwyn District Council
Post-Sept 2010	NZAM, 5 Sep 2010	Geo TIFF	29 MB	Ministry of Civil Defence and Emergency Management
Post-Feb 2011	NZAM, 8-10 Mar 2011	Geo TIFF	52 MB	Ministry of Civil Defence and Emergency Management
Post-Feb 2011	AAM, 20-30 May 2011	Geo TIFF	78 MB	Christchurch City Council
Post-June 2011	NZAM, 18 & 20 Jul, 11 Aug, 25-27 Aug, and 2-3 Sep 2011	Geo TIFF	82 MB	The Earthquake Commission
Post-Dec 2011	NZAM, 17-18 Feb 2012	Geo TIFF	17 MB	The Earthquake Commission

These grids were developed from each LiDAR set using the Esri ArcGIS for Desktop software. An Esri terrain dataset was created for each set with a 5 x 5 m window and exported as a grid of surface elevations with a 5 m cell size. The representative points in the terrain dataset (the ‘point closest to the mean z-value’ within each 5 m window) were linearly interpolated to provide the cell centre elevations within the exported grid.

The LiDAR Metadata provides additional information about the raw point clouds and the accuracy of these grids is described in CGD Technical Specification 03 (see CGD Documents).