The theory of plate tectonics describes how the Earth’s surface is divided into moving plates, explaining the distribution of earthquakes, volcanoes, mountains, and ocean basins on our planet. The icy surface of Jupiter’s moon Europa is the only other place in our solar system with evidence of surface motions like plate tectonics.
A new study provides the most comprehensive look yet at possible plate tectonic activity on Europa. Based on a global map of Europa created from images taken by NASA’s Galileo orbiter, they extended earlier work to encompass additional surface regions and a more complex geometric approach.
Scientists identified prospective tectonic plates as contiguous geographic areas bordered by surface discontinuities. Inferring a chronological sequence of activity at the boundaries based on which discontinuities appear to lay atop or crosscut neighboring features, they identified these boundaries. After determining the order of events, they went backward from the most recent event to retrace the likely movements each plate would have undergone to align with its neighbors.
By applying this approach to three regions of Europa, scientists deemed most promising to have hosted past tectonic activity. They discovered that huge areas previously thought to be plates needed to be broken into smaller subplates along less visible boundaries to reconstruct the surface’s motion adequately.
Scientists noted, “This observation helps explain why some prior studies found that large plates did not reconstruct well or behaved in other unexpected ways.”
Regarding plate tectonic activity on Europa, the authors come to four significant conclusions: It occurs sporadically and is not happening right now. In the past, plate activity was constrained to short lengths of between 10 and 100 kilometers.
Scientists noted, “Each trait distinguishes tectonic activity on Europa from that on Earth. The driving mechanisms for Europa’s plate tectonic system are surely also different. To further reveal these mechanisms and to answer other questions about Europa, planetary scientists need more high-resolution observations, which the upcoming JUICE (Jupiter Icy Moons Explorer) and Europa Clipper missions will hopefully provide.”
Journal Reference:
- Geoffrey C. Collins et al. Episodic Plate Tectonics on Europa: Evidence for Widespread Patches of Mobile-Lid Behavior in the Antijovian Hemisphere. Journal of Geophysical Research: Planets. DOI: 10.1029/2022JE007492