Drilling into an earthquake zone: ANZIC experts on Expedition 405
J-TRACK: Japan Trench Tsunamigenesis
The expedition to the Japan Trench – also known as JTRACK – is operated by JAMSTEC using the deep-sea drilling vessel Chikyu.
ANZIC is proud to send three talented expeditioners on this epic last expedition of IODP, including our very own Director!
Ron Hackney, ANZIC Director, will be part of the onboard science party for seven weeks, working as part of the physical properties team.
“This project is bold, ambitious, collaborative and multinational – everything that characterises IODP!”
“I’m excited to be part of an amazing team of international experts,” says Ron, “all putting their heads together to unpick the details of how earthquakes and tsunamis occur, so we improve prediction and reduce their impact. It will also be terrific to get an inside view of how expeditions work – I think that will add a lot to my role as Director.”
Science and outreach!
In addition, two ANZIC expeditioners will sail as outreach officers, each for a two-week stint – Lisa Smith, Communications Officer from Curtin University, and Will Grant, Associate Professor in Science Communication at the Australian National University.
“As an outreach officer,” Lisa tells us, “I’m always eager to explore scientific fields beyond my own expertise, and this expedition will be a hub of brilliant minds from various disciplines, countries and cultures. I’m passionate about learning, and I have no doubt this experience will teach me countless new things.”
Will sails as a Science Communications researcher – rather than practitioner – the first on an IODP expedition. His enthusiasm about the voyage, and research opportunity, is infectious. “The whole experience will be such an adventure,” he grins.
Drilling into the earthquake zone
Expedition 405 will drill directly into the Tōhoku earthquake slip zone.
The most powerful earthquake ever recorded in Japan, the 2011 quake occurred where the Pacific plate slides beneath Japan (subduction zone). The stress accumulated at this junction over hundreds of years was suddenly released, causing the overriding plate – on which Japan sits – to skip upwards and eastwards by up to 50 metres. This shallow slip displaced a huge area of the seafloor (around 200 by 500 km!), forcing the ocean into a devastating tsunami.
Drilling up to a kilometre below the seafloor, under an ocean around six kilometres deep, core samples will be extracted from both sides of the fault line.
“There’s so much work, such complex engineering and impressive technology that has to come together in order to extract those little cylinders of Earth. But the cores can tell us so much,” says Ron. “It’s awe inspiring.”
(Modified from Bilek and Ley, 2002).
At the first site the team will drill through the overriding plate and into the subducting oceanic plate below, accessing the fault zone in the region that generated the large, shallow slip in 2011.
“This site was previously drilled – a year after the quake,” explains Ron. “It will be fascinating to see how the rocks have changed since then – have they cooled following frictional heating during the earthquake slip? Has the fault healed? How much has the stress built up in that area since the earthquake?”
“We will be working with the core samples as they are brought up from the fault zone. We’ll measure the density, porosity, strength and more of the materials recovered, plus examine the fluids within the rocks.”
The second site – on the other side of the fault – will sample the Pacific plate so that the team can study the rock and sediment being brought into the subduction zone. This will help to work out whether the incoming materials also influence earthquake slip.
Studying earthquakes
At both drill holes, a range of detailed measurements will also be taken and sensitive instruments will be installed to continue to monitor temperature at multiple depths within the fault zone long after the expedition has ended.
The resulting samples and data will take years to be fully examined, but will undoubtedly deepen our understanding of subduction zones – the details of how the composition and structure of the rock and sediment here control the mechanics of earthquakes and the deformation of the seafloor.
In past research with Prof Andrés Tassara at the Universidad de Concepción, Chile, Ron mapped the rigidity of the Earth’s crust and correlated this with earthquake propagation. In the aftermath of the 2011 Japan quake, those maps and understanding could have provided guidance to scientists grappling to model the likely consequences of the event in near real-time.
“Working in the busy ANZIC office doesn’t give a lot of time for research,” Ron points out. “I’ll cherish the opportunity to get back to those intriguing research findings from 10 years ago that still await a thorough explanation.”
Studying the scientists!
And while the scientists are busy with the intricacies of core analysis, Will Grant will be turning the microscope back around to study the scientists themselves.
“I’ll be talking to the scientists on board to understand how they conceptualise their work and how they think about communicating that work. Which audiences do they consider? How do they consider impact and what stories are they looking for?”
Lisa Smith will also be focusing on the scientists, as she creates a captivating video series looking in-depth at their daily experiences on board. The videos will give a unique insight into the on-board lifestyle, cutting-edge scientific research, and all the intricate processes involved in scientific ocean drilling.
“It’s not every day you get to immerse yourself in this kind of environment, and I can’t wait to experience life on board” Lisa says.
Learn more
Details of the research can be found in the Scientific Prospectus and the expedition site.
Stay up-to-date with Chikyu and expedition progress on X (formerly Twitter), Facebook and YouTube.
The previous expedition to the same site was JFAST – IODP Exp 343.