Australia to Correct Tectonically Induced GPS Discrepancy

Decades of continental drift mean that GPS coordinates in Australia are off by approximately 1.5 metres (5 feet), which has implications for self-driving cars and other applications that require very precise positioning. See coverage from Atlas ObscuraBBC NewsPopular Mechanics and the Washington Post.

Basically, the discrepancy comes from the fact that GPS is based on the Earth’s core rather than any point on the surface, whereas local coordinates are based on a geodetic datum—in Australia’s case, GDA94 (North America uses NAD83)—that is based on a fixed point on the surface. But with plate tectonics, points are not fixed: Australia moves northward at seven centimetres a year.

On 1 January 2017 Australia will shift its coordinates north by 1.8 metres, overshooting things a bit so that the continent and GPS will be in sync by 2020, with plans to keep the datum continually updated after that.

Author: Jonathan Crowe

Jonathan Crowe blogs about maps at The Map Room. His nonfiction has been published by AE, The New York Review of Science Fiction, the Ottawa Citizen and Tor.com. His sf fanzine, Ecdysis, was a two-time Aurora Award finalist.