The instrument used to measure an earthquake is called a seismometer. Seismometers are devices attached to or buried in the ground, which convert the earthquake vibrations into an electrical signal. This signal can then be sent to a recording device called a seismograph. The seismograph converts the electrical signal into a computer or paper readout, called a seismogram, which can be sent by telephone, radio or satellite to a central location where it is analysed by scientists. Several seismometers placed at different places can then be used to locate where the earthquake has occurred and its magnitude and depth.
The first seismometers used in Australia, installed at St. Ignatius' College, Riverview (Sydney) in 1909, were a Wiechert 1000 kilogram Horizontal Seismometer (Astatic Pendulum) and a Wiechert 80 kilogram Vertical Seismometer. The seismic signal was recorded on heat-sensitive, carbon paper using a drum recorder. The information was then analysed and a yearly bulletin was mailed to around 200 different observatories and scientific institutions throughout the world.
With the advent of large scale integration of electronics and satellite and internet communications, the current configuration of a new seismic station is very advanced in comparison with the historical paper drum recorders used in 1909. Current seismometers installed by Geophysical Networks weigh as little as 1.8 kilograms for the Lennartz LE-3Dlite to 66 kilograms for the Geotech KS54000 Borehole Seismometer and these measure both horizontal and vertical seismic information.
The output from the sensor is sent to a digitiser or a field processor (this converts a continuous analogue signal from the seismometer to digital packets which are ready for storage and transmission). This data is sent via satellite, internet or mobile communications in real-time back to Geoscience Australia. Data is then captured, analysed both automatically and manually for seismic events and broadcast via the internet to a large number of organisations around the world in less than one minute.
Below is a list of links to the providers of equipment currently used in Geophysical Network installations and upgrades. These links give the technical specifications and a brief overview.
Kinemetrics Quanterra Q330HR http://www.kinemetrics.com/p-77-Q330HR.aspx
Kinemetrics Quanterra Q330SR http://www.kinemetrics.com/p-78-Q330.aspx
Kelunji Echo http://www.esands.com/products/ProductPages/SEIS_Seismic_Recorders.html
Geoscience Australia GDAS
Nanometrics Taurus http://www.nanometrics.ca/index.php?option=com_content&task=blogcategory&id=44&Itemid=95
Nanometrics Trident http://www.nanometrics.ca/index.php?option=com_content&task=view&id=19&Itemid=71
Geotech KS54000 Seismometer http://www.geoinstr.com/ks54000c.htm
Geotech PA-23 Accelerometer http://www.geoinstr.com/pa23.htm
Guralp CMG3T Seismometer http://www.guralp.com/product-range/3t-seismometers/
Guralp CMG3ESP Seismometer http://www.guralp.com/product-range/3t-seismometers/
Guralp CMG40T Seismometer http://www.guralp.com/products/40T/
Guralp CMG5 Accelerometer http://www.guralp.com/products/5T/
Guralp CMG40T-1 Seismometer http://www.guralp.com/product-range/40t-seismometers/
Guralp CMG3TB Seismometer http://www.guralp.com/product-range/3t-seismometers/
Telstra NextG Wireless http://www.telstra.com.au/mobile/networks/network_info/nextg.html
ASCS Satellite http://www.ascs.com.au/products/vsat_hub_and_remote/idirect
Optus Satellite http://www.optus.com.au/portal/site/aboutoptus/menuitem.cfa0247099a6f722d0b61a108c8ac7a0/?vgnextoid=acf9d1475accc010VgnVCM10000029867c0aRCRD
Data Acquisition Software:
RefTek Command/Control (RTCC) http://www.reftek.com/products/software-RTCC.htm