When earthquakes occur, they can cause damage to all of the spheres of the Earth, such as the lithosphere, the atmosphere, the hydrosphere and the biosphere
LITHOSPHERE
The main impact of earthquake activity is on the lithosphere, as it is broken tectonic plates, which slide past one another and are responsible for the majority of Earth’s seismic activity. Under the metropolitan area in Adelaide, there are heavily compacted sediments and geological structures that soften the violent vibrations released when tectonic plates slide past one another (Britannica Encyclopaedia 2018). However, regions with less compacted sediments are subject to destructive vibrations that can rupture the lithosphere, move the Earth’s crust and cause the lithosphere to slump near bodies of water. An environmental geohazard that has such potential to alter the lithosphere so quickly poses a significant risk and high cost to those who choose to build in regions along fault lines (Britannica Encyclopaedia 2018).
If an earthquake has an approximately high magnitude, it can actually increase the height of mountains from centimetres to metres. This can be seen in the Flinders Ranges as the increase in mountain height is due to one side of the fault line moving up relative to the other side of the fault line and creating a steep elevation (Britannica Encyclopaedia 2018).
ATMOSPHERE
Earthquakes indirectly contribute to the enhanced greenhouse effect by releasing methane from fractures within the lithosphere to the atmosphere. Methane is a greenhouse gas that heavily contributes to the enhanced greenhouse effect as it absorbs radiation that is emitted from the sun and is reflected from Earth’s surface. This process warms the atmosphere and increases the atmospheric temperature (Geoscience Australia 2015).
HYDROSPHERE
Confined aquifers can be affected by earthquakes and tectonic plate movement. Confined aquifers that are in the region of an earthquake are likely to deform due to the movement of Earth’s crust. Permanent deformation of these aquifers lasts until the pressure within the aquifer equalises with the water table. Breakage of the lithosphere creates new lakes known as “sag ponds,” which increase groundwater flow from springs and displacing stream channels (United States Geological Survey 2014).
BIOSPHERE
The intense vibrations of the Earth’s crust causes severe damage to the homes of humans and to the habitats of animal species. The vibrations resulting from tectonic plate movement are severely intense that structures of all material collapse and kill humans or animal species that are unfortunate enough to be close to these structures. The creation of new springs and lakes created by ground breakage alters the surrounding environment and increases the potential for flooding, changes in the food chain and can cause animal behaviour in the area to be affected (United States Geological Survey 2014). Landslides release pathogenic molecules into the atmosphere, which impact human and animal health by being inhaled. Landslides are also intensely powerful and cause destruction to the environment when they occur (Geoscience 2015).
CURRENT EARTHQUAKE RISK AND AUSTRALIA’S RESPONSE TO CURRENT EARTHQUAKE ACTIVITY
Geoscience Australia monitors, analyses and reports on significant earthquakes to alert the Australian Government, state and territory governments and the public about earthquakes that occur all over Australia (Geoscience Australia 2015). Geoscience Australia utilises scientific instruments called seismometers, which detect earthquake activity and rely on a mechanical system to record the seismic activity of Australia onto paper. Geoscience Australia monitors seismic data from more than 60 stations on the Australian National Seismograph Network and in excess of 300 stations worldwide (Geoscience Australia 2015).
The accurate locations of seismometers are stored in a database accessible by an earthquake monitoring computer system. This system also has access to crustal velocity models which provide approximate and detailed information on how fast seismic waves travel through the Earth’s crust. 40 recordings are delivered within 30 seconds of being recorded by a seismometer to Geoscience Australia’s central processing facility located in Canberra through various satellite and broadband communication systems (Geoscience Australia 2015).
Seismic data is also provided by overseas Governments that have national seismic networks. Geoscience Australia utilises data from New Zealand, Indonesia, Malaysia, Singapore, China, the United States of America, Japan, Germany and France (Geoscience Australia 2015).
EARTHQUAKE ACTIVITY IN SOUTH AUSTRALIA 