The SRC has been fortunate enough to be involved in a landmark earth science project in Western Australia, as a supplier of some of the seismographs used in the project, and in assisting with one phase of the deployment of over 150 seismic stations.
What is the WA Array?
The primary task for the WA Array project is to use broadband seismographs at 40km spacing across the state to map the structure of the earth deep under Western Australia. If you are familiar with WA, you’ll know that to get that sort of coverage would require around 1500 seismographs, so instead of deploying them all at once, the Geological Survey of Western Australia (GSWA) has acquired around 160 sets of instruments that are being deployed for a year at a time in multiple phases over the 10 year project. If you want to take a deep dive into the project, check out the WA Array web site, or read on for a brief summary.
Stethoscopes, MRIs and CT scans for the Earth
How do you use seismographs to map the earth? By placing a grid of seismic stations over a large area and having them record data continuously, whenever there is an earthquake somewhere on the globe that is large enough to detect, we can analyse the seismic energy signatures. By determining the time that an energy wave takes to get to a station, then correlating the travel time to every other station, the speed of the waves between each point can be calculated. The velocity of the energy waves varies through different densities of rock, giving scientists a picture of the likely types of geology in the earth, and the location of interfaces between these geological structures. This provides one input into building the story of how different minerals have reached the surface over millions of years.
The video series below documents the three stages of each phase, from the deployment of the seismographs, through the 6-month data collection trip, and to the final instrument recovery and clean-up trip at the 12 month mark. But it’s not just data from seismographs that is being collected from this 40km grid – soil sampling, magnetotellurics (variations in the earth’s magnetics and electrical fields), and the local velocity characteristic of the rock at each site is also measured across these field trips.
Seismographs for continuous remote monitoring
The SRC’s Gecko seismographs are one of the tools used to record data in the WA Array. The Gecko accepts input from any type of sensor from any manufacturer (broadband and short period seismometers, geophones, accelerometers), storing minute-long or hour-long miniSEED files to a removable SD card, all set up without the need for a phone, tablet or laptop. The Gecko can even stream live data to a remote computer by connecting it to a cellular modem or Ethernet adaptor. The Gecko uses less than 1W of power, enabling it to run from a small solar panel and battery all year round. Find out more about the Gecko here.
The SRC is able to source seismic sensors from all over the world from a wide selection of manufacturers, including Reftek, Nanometrics, Silicon Audio, GaiaCode, and Smart Solo. We welcome any reputable sensor manufacturer to contact us with their default sensor parameters to add to the Gecko’s list of preset sensors. We can also supply and support digitisers and digital sensors from this global network of seismic equipment manufacturers, so please let us know how we can use our 50 years of experience to help you meet your earthquake monitoring goals.