Plots show data with errors. The minimum, maximum, and latest values are labeled.
The last data point is 11th January 2017, the period prior is 90 days.
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About
GPS/GNSS receivers determine very precisely positions on the surface of the earth. Geonet compute a daily position for each of their stations so we can track the deformation caused by the interaction of the Australian and Pacific tectonic plates.
Each day a reading of the station position is noted, this is called the "displacement from initial position". This is then deducted from the previous days position, to determine the amount of movement in the 24 hours in mm. This may be +/- .
Below each daily map is a table with the stations listed and the WE (West/East), NS (North/South) and the UD (Up/Down) reading.THE MAPS
Each station is located on the map at the center junction of the two direction indicators ( bar and the arrow). The I "error bar" is marked Black in the direction of movement, up or down vertically. The height of the bar shows the size of the movement in segments of approx 0.001mm to 4.0mm, 4.0mm - 8mm, over 8mm. The Grey segment of the bar is not relevant to the direction or size.
The Blue arrowhead points in the direction of horizontal movement, which may be NW, NE, SW, SE. It is very rarely directly N,S, W or E. Again the length of the arrow shows the size of the movement in segments of the same size as the I bar.THE MARKERS
some marker examples are shown below;
This one shows horizontal movement in a north east direction of between 0.001mm to 4.0mm and a down direction vertically of between 4.0mm - 8mm.
This one again shows horizontal movement in a north east direction of between 0.001mm to 4.0mm and but a down direction vertically of over 8mm (ie the bottom (black) section of the I is longer.)
This is similar to the first one in that it shows horizontal movement in a north east direction of between 0.001mm to 4.0mm and but this time in an upwards direction vertically of 4.0mm - 8mm (ie the top section of the I of a moderate length)
This is an indicator of heightened movement both horizontally and vertically. It shows horizontal movement in a south west direction of over 8.0mm and an upwards direction vertically of over 8mm (ie the top (black) section of the I of a long length)
These two markers are probably the most common size, both horizontal movement and vertical movement is in the 0.001mm to 4.0mm range, but the directions are different.
The left hand marker shows north west horizontal movement (below 4mm)(short blue arrow pointing up to the left) and upwards movement (below 4mm)(upper black section of the I bar).
On the other hand the right hand marker shows south east horizontal movement (below 4mm)(short blue arrow pointing down to the right) and downwards movement (below 4mm)(lower black section of the I bar).Below is a map with the COOK area station names, (click to open full size)
Other area maps will follow in due course.
