IS05, Hobart, Australia
Thumbnail profile: Tasmania
Tasmania is an island belonging to Australia, located 240 km south of the eastern side of that continent and separated from it by Bass Strait, one of the roughest bodies of water in the world. With an an area of about 68,000 km² and an estimated population of almost 500,000, Tasmania, the southern most of all Australian states, promotes itself as the Natural State and the "Island of Inspiration".
The island was first inhabited by the Tasmanian Aborigines at least 35,000 years ago. The first reported sighting of Tasmania by a European was in November 1642 by the Dutch explorer Abel Tasman. Captain James Cook also sighted the island in 1777, and numerous other European seafarers made landfalls there. Although the first settlement was by the British, early settlers were mostly convicts and their military guards, tasked with developing agriculture and other industries.
Geography and Weather
Tasmania was probably joined to mainland Australia until the end of the most recent Ice Age some 10,000 years ago. Today Tasmania boasts breathtaking coastlines, jagged mountains and dense forests. The island is also home to rare animals, the most famous of which is the Tasmanian Devil, named so by early European settlers because of its eerie nocturnal growl. Tasmania is also home to numerous plants that thrive in the National Parks and the Tasmanian Wilderness World Heritage Area. These areas account for over 33% the island's territory and provide habitats to many plants and animals surviving from the ancient southern super- continent, Gondwana, that included today’s Africa, New Zealand, Australia, India, Madagascar, South America and the Antarctic.
As for geology, Tasmania has the world's largest areas of dolerite rock, mostly Jurassic dolerite intrusions — upwellings of magma — through other rock types, sometimes forming large columnar crystals. In the northeast and eastern parts of the island, continental granites are prevalent while the northwest and west have mineral rich volcanic rock. Limestone pervades the south and northwest, forming magnificent caves. The combination of these different rock types offers incredible scenery, much of it distinct from any other region of the world.
Tasmania’s temperate climate — it is the only Australian state with any land south of the 40th parallel — has been described as similar to that of pre-industrial England. The central east area of the Midlands is fairly flat and predominantly agricultural. The west coast has a high rainfall which powers most of the hydro-electric projects while the south west region is densely forested, the National Park home to some of the last temperate rainforests in the world.
Infrasound station IS05 is located about 100 km northeast of Hobart, the island's capital, at a military training area in the village of Buckland, on Tasmania’s east coast. In conjunction with the CTBTO, the Australian Geological Survey Organization, now called Geoscience Australia, conducted the site survey in November 1999 to determine the most suitable location.
In terms of meeting the criteria for minimizing the background noise levels and offering the best security and infrastructure conditions, the Buckland Military Training Area was identified as the most suitable for the installation of IS05. Station construction was completed between April 2002 and March 2003, when data collection and transmission to Vienna were initiated.
The Hobart Infrasound site is controlled by the Australian Department of Defence, and supervised by a permanent caretaker employed by Geoscience Australia. The IS05 infrasonic array consists of eight array elements and of a Central Processing Facility (CPF). The elements of the IS05 array are all located in forested areas for wind noise protection and are equipped with wind-noise-reducing pipe arrays with a diameter of 18 metres.
Each array element has a high-sensitivity microbarometer that measures micropressure changes in the atmosphere, a data acquisition system, fibre-optics communications equipment and power supplies with backup capabilities. In order to minimize temperature variations and to secure against bushfires and vandalism, the microbarometer, data acquisition system and associated electronics are located within a small, buried vault.
Geoscience Australia has also installed independent satellite communications equipment to transmit station state-of-health data to the Australian National Data Centre (NDC) in Canberra. This allows staff at the NDC to monitor the station in real time, to identify and diagnose problems quickly and to initiate remedial action.
Testing and Certification
Since the completion of the equipment installation at Infrasound Station IS05, the station has operated with high reliability and only experienced two faults. Data was transmitted continuously from all array elements to the International Data Centre (IDC) during the testing phase. Average data availability was above the required 98%. IS05 was therefore certified on 22 December 2003 as the 16th infrasound station in the 60-station network.
Australia hosts 21 International Monitoring System (IMS) facilities representing each of the CTBTO’s verification techniques: four primary and three auxiliary seismic stations, one hydroacoustic station, five infrasound stations, seven radionuclide stations and one radionuclide laboratory. Between 1952 and 1957, the United Kingdom conducted 12 atmospheric nuclear explosive tests and numerous smaller trials in Australia.