Port Hills, Christchurch landslide monitoring
After the February 22 2011 Christchurch earthquake, GNS Science installed continuous GPS (cGPS), water-level and rainfall monitoring equipment on selected landslides in the Port Hills suburbs of Christchurch. The purpose of the monitoring is to provide data for research into the post-earthquake performance of these landslides. The equipment is not maintained to provide an automated hazard warning. Installation and monitoring of the sites is carried out under the GeoNet project. The monitoring data are freely available to anyone via the links below.
A cGPS installation together with the weather station set-up at Sumner.
Another typical cGPS installation in the Port Hills.
The installed equipment
- Surface movement is monitored by continuous GPS equipment (cGPS). At each site, a cGPS antenna is mounted on a tripod.
- Water levels are being monitored in four borehole piezometers that were drilled into the ground.
- A weather station has also been installed in the Sumner area.
The equipment is powered by batteries with solar recharge. The collected data are sent via the mobile phone network to the GeoNet Data Centre in Lower Hutt.
The monitored sites
| Site code | Equipment installed | Date installed | Comments |
|---|---|---|---|
| VR27B | cGPS | 9/03/2011 | Operational |
| VR47B | cGPS | 9/03/2011 | Operational |
| CLSK | cGPS | 2/03/2011 | Operational |
| CLSG | cGPS | 2/03/2011 | Removed |
| CLS3 | cGPS | 21/06/2011 | Operational |
| CLS4 | cGPS | 21/06/2011 | Removed |
| CLS5 | cGPS | 21/06/2011 | Operational |
| CLS6 | cGPS | 13/10/2011 | Operational |
| WPA | Water level | 3/11/2011 | Operational |
| WPB | Water level | 1/11/2011 | Operational |
| WPC | Water level | 31/10/2011 | Operational |
| WPD | Water level | 1/10/2011 | Operational |
| WS1 | Weather station | 9/03/2011 | Operational |
Monitoring of these sites does not mean that continuing movement is necessarily expected to occur. However, if future movement of these sites were to occur, then the information from the monitoring would be useful to assess what factors may have contributed to the movement. These factors typically include rainfall and/or further earthquakes.
How are the data used?
- The cGPS instruments solve for the antennae position, comprising an easting, northing and vertical component each 30 seconds; positions are averaged over a 24-hour period to give an average daily position. These daily positions are filtered relative to another cGPS located on Banks Peninsula (site code MQZG at McQueens Valley), which has been assessed as being on stable ground. The purpose of the filtering is to remove regional movement patterns such as those related to normal tectonic plate motion. However this filtering may not eliminate all of the regional deformation associated with post-February 22 tectonic adjustments. The movement data of the cGPS sites can be viewed using the GPS Time Series application.
- The water levels in the monitored boreholes are being recorded at 5-minute intervals. No barometric corrections are applied to these data. Water level depths are recorded as the height of the water column above the sensor tip.
- The weather sensor records rainfall, barometric pressure, temperature and wind speed and direction.
Where do I find the data?
The collected data sets are available in the Resources section of the website.
