Landslides and tsunamis under investigation on Australia's east coast
Australia's coastline may be vulnerable to rare landslides with potentially disastrous consequences, according to ongoing research by the University of Sydney.聽
Undertaken by the University鈥檚 ,聽the research is detailed in a chapter in , a new book from CSIRO Publishing. 聽
It鈥檚 hard to understand how these slopes ever fail yet the evidence is they can, because there are enormous scars, or scoops, along the continental margin from Batemans Bay to Fraser Island,鈥� said , lead researcher on the project.
鈥淥ne of the largest examples of these continental scars is located off Bulli in New South Wales, and is 16 kilometres long, nine kilometres wide and roughly 300 to 400 metres thick.鈥�
Importantly, the landslide events and the earthquakes that could trigger them are considered to be extremely rare, according to Associate Professor Hubble and his team.
鈥淵ou might get one landslide every 10,000 years that could generate a wave of more than five metres in height. A wave height of more than 20 metres would only occur every 100,000 or even every million years.
鈥淭he big questions for us are how many, how big and how often? And we鈥檙e making some progress on this.
鈥淲e have actually identified 400 landslides that have occurred over the last 4 million years that are big enough to have generated a tsunami, most of which would have generated a tsunami with a one to two metre wave height.
鈥淎round 50 to 100 of these could have generated something around five to 10 metres in wave height, which is the size of the tsunamis that came through Indonesia and Japan.
鈥淲e need to do more investigation to constrain these numbers reliably.鈥�
The big questions for us are how many, how big and how often?
Researchers believe the landslides could be triggered by large earthquakes, likely of magnitude six to seven, and are now investigating this theory.
鈥淲e are interested in conducting further studies in a section referred to as 鈥榯he Block鈥� near Brisbane, which is about half a kilometre thick and 10 kilometres long, and has noticeable tension cracks.
鈥淚f an earthquake of the right magnitude occurred, we believe it could trigger a significant tsunami,鈥� said.
Understanding these scoops and their potential sites, as well as their tsunami generating capabilities, has so far been restricted by the sonar technology on board the vessel Southern Surveyor, which could only map the sea floor to 3000 metres. The continental slope begins about 50 kilometres off the Australian coast and drops away to the abyssal plain, which is 4000 to 5000 metres deep.
Southern Surveyor: Stories from on board Australia鈥檚 ocean research vessel follows the adventures of the men and women on board the CSIRO Marine National Facility research vessel over the course of a year, as told by author Michael Veitch.
For 10 years, the Southern Surveyor represented the vanguard of Australian blue water marine science. On more than 100 voyages, this former North Sea fishing trawler with her distinctive blue and white livery carried scientists and technicians across the Southern, Pacific and Indian Oceans as well as the waters off northern Australia.聽