Taihape Landslide Graphing Application

Introduction

The Taihape landslide first moved between 1,800 and 11,000 years ago. Several previous studies of the landslide have been carried out, the earliest in 1971 when significant instability was first noticed. Find out more about the Taihape landslide and retrieve the data sets.

The time series graph below uses a common horizontal time axis and three separate vertical sub-axes to display daily rainfall, groundwater level and cumulative displacement across the landslide. These measurements were calculated using automated readings taken by GeoNet instrumentation situated on the landslide. Users can select individual or multiple sites to display using the reference numbers.

System Requirements

• The graphing application requires Java Runtime Environment version 5.0 (or higher). If you don't see a blank graph appear, Java may be disabled by your browser, or you may have an older Java version installed. To find out which Java version your browser supports, try the following web pages:
  • http://java.com/en/ download/installed.jsp or
  • http://javatester.org/version.html
• For further help installing and running Java, try: http://java.com/en/download/help/
• The mapping/location application requires Adobe Flash Player version 7 (or higher). If you don't see a map of Taihape and the associated monitoring equipment pop-up after clicking on any of the links to the Taihape location map you may have an older version of Flash Player or it may be disabled by your browser.
• The mapping/location application also requires that your browser accepts javascript generated pop-up windows. If nothing happens when you click on a link to the Taihape location map your browser may have javascript disabled, or the pop-up may have been blocked by your browser.
• Depending on the security settings of your browser and Java Runtime Environment you may see a security warning dialogue. This warning should indicate that the applet has been verified as signed by GNS Science and is making a request for privileges above and beyond what is typical for a Java applet. The extra security is only required by the applet if you wish to print or save copies of the generated graphs to your computer. If, at the security warning dialogue you click on the "No" button, the applet will continue to function with these features disabled.

Usage Instructions

To view the data for the different prisms, piezometers and rain gauges please click on the reference number at the left hand side of the graphing window and select refresh or reload on your browser. You can also navigate to it using the arrow keys on your keyboard and selecting it using the space bar. To select multiple sites for plotting on a single axis:

• Hold Ctrl (Mac = Cmnd) while selecting sites, to toggle their selection.
• Hold Shift while selecting sites, to select a sequential list of sites.

The application will retrieve the relevant data and plot it on the corresponding vertical axis.

A map showing the locations of the various instruments can also be found on this page. The different instruments can also be selected from the map, and the data for the chosen instruments will be shown once the refresh button has been clicked. Use the location map to visually select sites with your mouse; they will then automatically be selected in the graphing application below. You can change between selecting prism sites, piezo (groundwater level) sites and rainfall by selecting the desired site-type from the drop-down list, at the top right of the location map.

You can select an area to zoom into the plots by using a top-left to bottom-right, (left) click-and-drag motion. This will select the same time-range across all three plots.

To view a moving average for a rain gauge site, select the number of days for the moving average calculation on the moving average slider and the site(s) you wish to plot the moving average for (prefixed by "MAVG_").

Selecting "Refresh" re-paints the entire graph (including all selected plots).

Selecting "Clear" clears all selected sites and re-paints the entire graph (empty).

Right clicking your mouse (PC) or Ctrl+Click (Mac) directly on the graph below will display a menu enabling further application functionality, such as printing or saving the graph to file. Note that parts of the menu functionality may be disabled if Java does not verify and accept the application's digital signature.

What does it show?

The data shown on Graph A are the horizontal movement (displacement) calculated for each prism installed on the landslide. The main direction of landslide movement is approximately 160 degrees (towards the south-east) and so the displacement of each prism has been calculated in this direction. The data plotted on Graph A represent the average movement (of each prism) over a 24 hour period (daily average), with the data plotted cumulatively to give an indication of the total movement since monitoring began. The spikes in the data (shown on Graph A) are a result of the pressure and temperature fluctuations across the area. These are typically in the range of 1 to 3 mm and are essentially errors in the measurement process. It is therefore important when assessing movement of the landslide to look at the trends in the data rather than individual measurements. The data shown on Graph B are from the piezometers and have been shown as a water level relative to the ground surface in each of the 4 locations, and the data in Graph C show the daily rainfall.

The information contained on this website is designed to give the viewer an overview of the monitoring carried out by GNS Science. Much more detailed information has been gathered for the landslide, and this information is used to assess the movement patterns of the landslide to aid in the implementation of mitigation works currently being assessed by EQC and Rangitikei District Council.

Disclaimer

GNS Science carried out a study to further scientific understanding of landslide behaviour and processes. This study has been funded through the Earthquake Commission, Foundation for Research Science and Technology and GeoNet. The study used a combination of ground investigation and monitoring techniques to assess the movement characteristics of large, deep-seated landslides. The Taihape landslide forms part of this study. The information regarding the Taihape landslide on this website is not a substitute for a professional site inspection and an engineering/geotechnical report for any particular property and is not provided for lending purposes. GNS Science excludes, to the full extent permitted by law, liability for damages or losses suffered or incurred as a result of any person or organisation's use or reliance on the information or any failure of the information to be accurate, up to date, not misleading or fit for any particular purpose.