August 25: Macca on the move.....

One of the science projects that we support here at Macquarie Island, is Geoscience Australia's Global Navigation Satellite System (GNSS) installation.

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.

Checking out the GNSS. Photo: Mark Baker

Trying to work out where the antenna cable should be plugged in. Photo: Mark Baker

May 6: A morning in the ARPANSA Lab

 

Whenever people hear that you work for the Antarctic Division, they assume that you are a scientist, or an explorer!?!  Well that has frequently been my experience.  I am neither, with my job as station leader being mostly to manage the facilities and the team of people here.  The exception to this however is the few times a month when I fill in at the ARPANSA lab - and wear the lab coat!

Nerd out alert.  I'll keep it non-technical.

"ARPANSA??",  you say?  So did I, when I found out that I was volunteered for the role.

Australia is a signatory to the  Nuclear Test Ban Treaty.  To monitor potential nuclear testing activity there is a network of stations all over the world, measuring seismic, sound and air quality. 

This network picked up and mapped the plume from the recent Fukishima melt down.

At Macca we have an air monitoring station. This is important as we have quite clean air down here, and there are not many inhabited land masses this far south on which to locate such a facility.

So we complete a daily filter change and measurements for ARPANSA.

Each day at 0900hrs, we take a filter paper which has filtered the air for 24 hours.  We crush it into a small disk with a hydraulic crusher, then we put it into a decay cabinet for 24 hours to let much of the background radiation  decay off.  After this the filter disk is then placed into the detector for another 24 hours where it is tested to see if any radiation is detected that is likely to indicate a nuclear test. The results get sent to the international organisation in Vienna.



Starting up the air filter after filter change over. Photo: Jacque Comery

 

Removing the quality control source from the detector. Photo: Jacque Comery

Loading the filter press. Photo: Jacque Comery