Australia seismicity

The Earth is a dynamic planet consisting of an outer crust riding on so called lithospheric plates that are roughly 100 km in thickness. Australia lies within one of these plates. The lithospheric plates move relative to one another at rates that are typically around several cm per year. In some places, oceanic plates are gradually plunging into the Earth's mantle such as under Japan and Chile whereas at mid-ocean ridges, new crust forms as the plates move apart. It is the movement of the lithospheric plates that induces stresses in the crust and causes mountains and faults to be created both at plate margins and within plates. The Australian plate has been subjected to enough stress for mountain ranges to have formed and the present stresses are sufficient for earthquakes to occur.



On 28 December 1989, an earthquake measuring 5.6 on the Richter scale hit Newcastle. The epicenter was 15 km south-southwest from the city center. This earthquake caused widespread damage, damaging 50 000 buildings and killing 13 people. Damages are estimated to have cost $1.5 billion. The death toll from the earthquake could have been a lot worst. Fortunately, school was not in session at the time, as many schools were badly damaged.Although 5.6 is generally considered to be only a moderately strong earthquake, many buildings were destroyed. This was due to a number of factors. Newcastle was considered to have a low seismic risk, so buildings were not expected to adhere to earthquake standards. Many of the damaged buildings were built on alluvial land, or land deposited by water, which is affected more strongly by earthquake waves. The shaking went on for a very long time, 35-40 seconds. Finally, the focus was very shallow at only 11 km below the surface of the Earth. While the earthquake's measurement on the Richter scale was moderate, its measurement on the Mercalli scale would have been much higher.This paved the way for new building codes and tighter enforcement. 





Sources: http://en.wikipedia.org/wiki/Queensland
http://www.ses.sa.gov.au/site/community_safety/earthquake_information.jsp
http://www.seismicity.see.uwa.edu.au/welcome/seismicity_in_australia

Australia Minerals & Rocks

Friday, February 13, 2015

Australia Minerals & Rocks

Surprisingly Australia has a abundance of minerals, rocks and metals. 

Copper which is found in the states northern territory. Australia is also the worlds 6th largest producer of copper


Australia is the world’s largest producer of bauxite and a significant global supplier of high value downstream products, including refined alumina and smelted aluminium metal.
Australia has substantial gold resources which are located in all States and the Northern Territory. Gold attracts Australia’s second largest exploration expenditure.Australia is the world’s largest exporter of coke and coal for steel-making, and we are one of the world’s two largest exporters of iron ore. As well, we’re the world’s second-largest producer of gold and we’re really preeminent in mineral-sands exports, that’s both for titanium and zircon.
Iron constitutes about five per cent of the Earth's crust and is the fourth most abundant element in the crust. Australia is one of the world’s major iron ore producers.
theirs also metals like: 

• Tin
• Tungsten
• Tantalum
• Lithium
• Niobium
• Magnetite
• Molybdenum
• Vanadium
• Phosphate rock
• Zinc
• Lead
• Silver'

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Australia’s substantial diamond resources are mostly associated with the world-class Argyle deposit in the Kimberly region of Western Australia. Other smaller resources are associated with small diamond pipes at Ellendale in Western Australia and Merlin in the Northern Territory with each containing about five million carats.

                                                  

sources : http://www.ga.gov.au/
http://museumvictoria.com.au/

The Australian Plate

The Australian Plate

The Australian plate is heading north while the Pacific plate is heading west. The combination of these motions means that the Pacific plate, which includes much of the South Island, is moving relative to the Australian plate at a rate of about 40 millimeters each year

                         

intro to australia

Australia experiences a range of 'natural disasters' including bushfires, floods, severe storms, earthquakes and landslides.  These events cause great financial hardship for individuals and communities, and can result in loss of life. However, these events are also considered both part of the natural cycle of weather patterns in Australia as well as being affected by human factors such as overstocking, vegetation loss, dams, groundwater and irrigation schemes. These patterns are recognised by terms such as a 100-year drought – a drought of severity that is only seen once in a hundred years.  Fire can often follow drought, and drought can be followed by flood.  Severe fires followed by drought can also contribute to soil erosion.

Canberra firestorm, 2003

In mid-January 2003, extreme weather conditions led to multiple outbreaks of fire in Namadgi National Park to the south of Canberra.  Strong winds pushed the fires into forested areas adjoining Canberra and on the afternoon of Saturday 18 January, firestorms fanned by high winds hit Canberra suburbs²⁴. Thousands of hectares of forest and park lands were burnt out

The Millennium Drought
The 2002–2007 drought, or ‘big dry’, was actually two separate droughts, each of about 12 months duration, 2002–03 and 2006–07, which resulted from two separate El Niño events. Crucially, there was no significant wet period between the two events to alleviate the rainfall deficiencies. Not only did the 2002–2007 drought significantly reduce farm production during the event but ongoing effects continued to be felt in many regions following the return of ‘normal’ rainfall patterns.