We know more about the topography of Mars than that of Earth because 70 per cent of our planet is covered by water.

Now University of Sydney PhD student Kara Matthews has used satellite data and GPlates, a computer package developed at the University, to create a complete digital map of the many geological features of the seafloor.

Fracture zones—the orange lines in the accompanying image—are deep linear scars on the seafloor that extend perpendicular to the boundaries where tectonic plates are moving apart, revealing up to 150 million years of plate movement. They are accompanied by huge ridges on the seafloor, rising up to 2 km above the abyssal plains, and valleys as deep as 8 km below sea level.

Through her work, Kara has discovered ancient tectonic microplates—tiny plates rotating like spinning tops over geological time—as well as kinks in fractures zones which record sudden shakeups of the global tectonic plate network. “The forces driving these changes are still largely unknown,” says Kara, “so I am exploring different mechanisms using supercomputer simulations of the slow convective churning of the Earth’s mantle, where rocks flow like warm toffee.”

Kara’s map is freely available to the community, and her research will enable more accurate mapping of plate movements. Earthquake hazard maps will be improved by considering the intersection of fracture zones with subduction zones, where plates are converging. The detailed topographic data may also improve modelling of deep ocean circulation, and thus enhance our understanding of long-term climate change.

Photo: Kara Matthews has mapped the seafloor using satellite data and software. Credit: Kara Matthews

Credit: Kara Matthews

School of Geosciences, The University of Sydney, Kara Matthews, kara.matthews@sydney.edu.au, www.earthbyte.org