Geoscientists identify seismic activity in Southern Australia including the Flinders Ranges
Australia is not as geologically stable as many think. Despite popular belief, Australia is a geologically active continent with moving fault-lines, regular seismic activity, and a long history of mountain making, said internationally respected geologist, Associate Professor Malcolm Wallace from the School of Earth Sciences at the University of Melbourne.
We have discovered substantial evidence of ancient and current mountain building on this continent, and seismic activity which commenced 10 million years ago and continues to this day,” Associate Professor Wallace said.
“Two separate geological studies have concluded that an area from Adelaide to south-east Victoria is seismically active and the next ‘big one’ could endanger lives and infrastructure”.
“There are numerous young faultlines weaving their way across southern Australia, including one that goes right around the perimeter of Adelaide. There are also young faultlines running through the Mornington Peninsula outside Melbourne, the Strzelecki Ranges in Victoria and the Flinders Ranges in South Australia.
The University of Melbourne geologists have uncovered evidence that parts of South-eastern Australia recently stirred from their geological slumber and are in an active mountain building phase. These mountains are being shaped by earthquakes, some reaching greater than 6 on the Richter scale.
Submission: Seismic hazards SA
[The area between Quorn and Leigh Creek has the highest number of seismic events (considered to be related to zones of crustal weakness)]
“Their seismic activity is generated by tectonic plates pushing up against each other on a daily basis, so it is critically important that scientists and emergency management agencies know of their whereabouts and the potential risks they pose – this is where geoscientists play a crucial role.”
“Some faults around Adelaide have moved slabs of the continent up to 30 metres in the last one million years,” says ARC Professorial Fellow, Mike Sandiford.
“When these big quakes reoccur, they have the potential to cause catastrophic damage to cities such as Melbourne, Adelaide, and the La Trobe Valley area, which straddle some of these major faults lines,” says Professor Mike Sandiford also from the School of Earth Sciences at the University of Melbourne, who conducted one of the studies.
Possibly, the most dramatic indication of this geological stirring, which the studies estimate began suddenly about ten million years ago, can be found in the landscape of the Mount Lofty Ranges near Adelaide.
“A typical earthquake of magnitude 6.0 might produce a displacement of about one metre. Thirty metres is equivalent to 30-50 big earthquakes in the last million years,” he says.
Other areas of intense mountain building have been around Victoria’s Otway Ranges, Mornington Peninsula and Strzeleckis. In some of these areas, similar uplift and erosion over the last 10 million years have thrust chunks of Australia upwards in the order of one kilometre.
Tectonic movements have pushed the Otways 250 metres higher in the last three million years, and The Selwyn fault, which runs from Mt Martha, on Victoria’s Mornington Peninsula, east to the Dandenong Ranges has possibly produced six metres of uplift in the last 100,000 years.
“This is potentially six big earthquakes,” says Sandiford. “We are still trying to determine the slip rates along these fault lines, but our evidence so far suggests that we should expect, on any one of the major faults, a large earthquake every 10-20,000 years. The estimated return period of a quake greater than 6.0 in south-east Australia is about 30 years, but none have been recorded in the last 100 years,” he says.
Associate Professor Malcolm Wallace has undertaken significant research on the environmental and climatic evolution of the southern Australian margin. His research on greenhouse/icehouse climate and environmental evolution of Victoria for the last 80 million years has formed an important geological analogue for future climate change in Victoria.
Associate Professor Wallace was the recipient of the prestigious Geological Society of Australia (Victoria Division) Selwyn Medal for 2008. The Medal, named in honour of Sir Alfred Selwyn, an eminent Victorian pioneering geologist and founder of the Geological Survey of Victoria. recognises significant ongoing or former contributions of high calibre to any field of Victorian geology.
Induced seismicity - Wikipedia
While most earthquakes are caused by movement of the Earth’s tectonic plates, human activity can also produce earthquakes.
Four main activities contribute to this phenomenon: constructing large dams and buildings, drilling and injecting liquid into wells, and by coal mining and oil drilling.
Perhaps the best known example is the 2008 Sichuan earthquake in China’s Sichuan Province in May; this tremor resulted in 69,227 fatalities and is the 19th deadliest earthquake of all time.
The Zipingpu Dam is believed to have fluctuated the pressure of the fault 1,650 feet (503 m) away; this pressure probably increased the power of the earthquake and accelerated the rate of movement for the fault.
The greatest earthquake in Australia’s history was also induced by humanity, through coal mining. The city of Newcastle was built over a large sector of coal mining areas. The earthquake was spawned from a fault which reactivated due to the millions of tonnes of rock removed in the mining process.
Waking a Sleeping Giant: Human-induced Earthquakes
By Johnny Kilroy on January 21, 2010
Attention has been focused lately on the risk of earthquakes from human activity.
A number of studies suggest that geothermal drilling, mining, groundwater-extraction or injection, reservoir filling, nuclear explosions, and enormous manmade structures may all be responsible for seismic events…….
Mining leases and Mineral Tenements in South Australia
Primary Industries SA (PIRSA)
The risk of volcanic eruption in mainland Australia E. B. Joyce (CSIRO)
The young volcanoes of the Australian mainland are made up of the Newer Volcanic Province of Victoria and southeast South Australia (NVP), and a number of separate provinces in far north Queensland.
These volcanic fields are similar in age, and in their numerous scattered scoria and lava cones, extensive basalt flows, and maar/tuff ring eruptions of phreatic origin.
Australian volcanologists and seismologists now agree that youthful ages imply the possibility of further activity.
Post Mortem on Solomon Islands 8.1 Earthquake/Tsunami of 2007
By Gary Robbins, UNION-TRIBUNE STAFF WRITER
Student from the San Diego Universiity travel to Solomon Islands to study the ecological and social impact of the magnitude 8.1 earthquake that hit that region on 2 April 2007. The quake generated a 10 metre tsunami. The official death toll was 52 and several thousand displaced people.
[The earthquake occurred along the boundary of the Pacific plate with, respectively, the Australia, Woodlark, and Solomon Sea plates]
The earthquake itself uplifted and in some places sank the landmass and adjacent marine habitats. This severely damaged some marine habitats that previously supported a productive fishery – the basic source of household protein and income for the indigenous communities of the region….Gary Robins reports.
The massive magnitude 8.1 earthquake that jolted the Solomon Islands on April 1, 2007, permanently changed the shoreline on Ranongga Island, west of the epicenter. New beach was added to the western shore of the island when the earthquake lifted the island as much as three meters, exposing near-shore coral reefs, (Australian Broadcasting Corporation).
NASA: The Earth split like a zipper.
….”the entire rupture didn’t happen instantaneously. Instead, the earth split like a zipper, progressing from south to north over several minutes.
At least 40 people killed, an undetermined number missing and several villages destroyed by the earthquake and tsunami. About 300 homes, schools and a hospital were destroyed at Sasamunga and about 500 houses were damaged at Gizo. Tsunami damage also occurred on Lefung and Taro. Two people were killed by landslides on Ranongga, where uplift was also observed. Felt at Honiara.
A 2 meter wave was measured on Woodlark Island, Papua New Guinea, where 17 houses were destroyed and a church was damaged. The tsunami also caused damage on Rossel Island and Bougainville.
The Solomon Islands earthquake of April 1, 2007, occurred along the boundary of the Pacific plate with, respectively, the Australia, Woodlark, and Solomon Sea plates. The latter three plates converge to the east-northeast or northeast against the Pacific plate with velocities of 90-105 mm/y.
Could Exxon-Mobil Works Have Tripped Indonesian Tsunami?
by Paul Noel, JAH, Sterling D. Allan and Mary-Sue Halliburton