Australia's eastern edge: marine landslides and canyons
Dr Hannah Power from the University of Newcastle examines the amazing landscape of the sea floor.
Did you know that the sea floor isn’t just flat and featureless? The landscape of the sea floor is amazing and is filled with canyons, mountains and all sorts of other interesting things. On the southeast Australian continental margin (SEACM) scientists have discovered giant underwater landslide scars. Dr Hannah Power has gone to sea to examine sediments and identify exactly how old these scars are!
Watch 'Australia's eastern edge: marine landslides and canyons' (03:30)
(Duration: 3 minutes 30 seconds)
[Red and blue logo revealed reading ‘STEM 2022 on demand’.]
Dr Hannah Power:
[Screen shows the open sea.]
Did you know that the sea floor isn't just featureless and boring and flat?
[Screen shows Dr Hannah Power standing in front of a screen showing a large ship in a harbour.]
It actually has lots of really different things down there. This includes things like underwater mountains, big underwater canyons, and even big underwater submarine landslides.
[Screen reads, ‘Dr Hannah Power, University of Newcastle’. Screen shows Hannah wearing a large red jacket and hard hat.]
I'm Dr. Hannah Power. I'm an associate professor of coastal marine science here at the University of Newcastle.
[Screen shows a photograph of 13 people in high visibility vests, in front of a ship hull. Hannah is among them.]
For the last five weeks, I've been at sea with 52 other people, including a whole bunch of scientists, to map and collect samples from the ocean floor.
We've been doing a whole lot of work trying to understand how the sediment that includes the sand and muds that come off our continent travel off down into the deep oceans.
As we move off from the coastline, we go out onto the continental shelf where it's relatively shallow and we're still on the Australian continent. We then go off the edge of the continent and down the continental slope and that's where lots of interesting things happen.
[Screen shows a satellite image of Australia. The water directly around Australia is light blue. The blue of the water is darker further out to sea and is light again near the surrounding countries and islands. The screen zooms into the East Coast of New South Wales, highlighting the contrast between the light blue and dark blue.]
As we get to the bottom of the continental slope, we go off the edge of the continent and out onto the deep ocean plains, and they're called the abyssal plains.
On the south east Australian continental margins scientists have discovered really big scars from underwater landslides. These are up to ten or 20 kilometres long and several kilometres wide. What that means is that that material has been removed from that location in our continent.
[Screen shows an image of large, crashing waves.]
And depending on how it's removed, it may or may not have the potential to form tsunami.
[Screen shows a ship at sea. The ship is named ‘Investigator’ and across the middle of the ship it reads, ‘Marine National Facility’.
Screen shows two people scooping sediment into buckets from the floor. The t-shirt of one of the people reads, ‘The University of Newcastle’.]
By going to sea and collecting sediment samples from these landslide sites, we're able to date them and identify when they formed. We can also then look at how that material has failed. Has it all gone as one single mass or has it come off in bits and pieces? And this is really important because it tells us how big a tsunami would have been generated.
[Screen shows a group of people opening a pipe filled with sediment. Screen then shows people scraping sediment our of the pipe and placing it in specimen jars. Screen then shows someone referring to a colour coded chart in a book and making notes in a notebook.]
So we had a really successful voyage and we were able to collect lots of samples of mud and sand from within these landslides. And one of the things we wanted to do was find out where this material ended up. Unfortunately, we couldn't find it. But the ocean is really big and we've only mapped about a quarter of the world's ocean in total. And so there's lots more places to look for us to find this material in future research.
Like any scientific research, you often come away with more questions than you do with answers, and that's what's happened to us. We've got a whole lot more questions that we want to answer now. And so we're hoping to be able to go to sea again to answer these new questions.
During our voyage, we travelled over 5300 nautical miles, and we mapped areas of seafloor that have never been mapped in high resolution before. We also imaged features like beaches and sand dunes that existed when sea level was 120 metres lower during the last ice age. We learned lots about all these different features on our seafloor, and that helps tell the story of how the Australian continent evolves through time.
There's a huge amount that we still don't know in the coastal and marine space. And so working in space is very, very exciting. We're always finding out new things and it's an excellent field to get into.
So I really encourage you, if you're interested in science, to get into this field and encourage others who are interested in it to get into it as well.
[Screen reads, ‘We would like to thank those who made this voyage and video possible:
Chief Scientist, Dr Thomas Hubble
Alternate Chief Scientist, Dr Hannah Power
The University of Newcastle School of Environmental and Life Sciences
The University of Sydney School of Geosciences
This research was supported by a grant of sea time on RV Investigator from the CSIRO Marine National Facility.’]
[Screen shows The University of Newcastle, Australia logo. Video concludes by displaying the NSW Government logo.]
[End of transcript]