Below is a time-series of the GNSS (Global Navigation Satellite System) data that has been collected at Macquarie Island since 2001. The station was established earlier than this, but the latest analysis of data is from 2001 onwards. GNSS is a fancy way of referring to GPS now days as the data we collect does not just include the US run GPS system, but also satellites systems operated by Russia (GLONASS), Europe (Galileo), China (Beidou) and a Japan (QZSS)
What the time-series shows is the movement of an antenna on an outcrop of rock beside the science building (which is hopefully anchored to bedrock) broken down into three components. The first plot shows the up-down movement (each dot represents a day). The second plot shows the north-south movement and the third plot the east-west movement. The red lines indicate discontinuities in the time-series (such as equipment changes or earthquakes). For example you can clearly see a displacement in 2004 when the Macquarie Island Ridge earthquake occurred.
From these plots it can be estimated where and how fast Macca is moving:
The current estimate based on the modelling would be approximately 10 mm/year to the east, 30 mm/year to the south and sinking 1 mm/year. It is important to note that some studies have shown that velocities (movement) of the island is still being influenced by the large earthquakes it has experienced over the last 100 years.
Thanks to Ryan Ruddick at GA for the info.
Thanks to Ryan Ruddick at GA for the info.
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| Checking out the GNSS. Photo: Mark Baker |
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| Trying to work out where the antenna cable should be plugged in. Photo: Mark Baker |
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