Episodic Plate Tectonics on Europa: Evidence for Widespread Patches of Mobile‐Lid Behavior in the Antijovian Hemisphere

A nearly pole‐to‐pole survey near 140°E longitude on Europa revealed many areas that exhibit past lateral surface motions, and these areas were examined to determine whether the motions can be described by systems of rigid plates moving across Europa's surface. Three areas showing plate‐like behavior were examined in detail to determine the sequence of events that deformed the surface. All three areas were reconstructed to reveal the original pre‐plate motion surfaces by performing multi‐stage rotations of plates in spherical coordinates. Several motions observed along single plate boundaries were also noted in previous works, but this work links together isolated observations of lateral offsets into integrated systems of moving plates. Not all of the surveyed surface could be described by systems of rigid plates. There is evidence that the plate motions did not all happen at the same time, and that they are not happening today. We conclude that plate tectonic‐like behavior on Europa occurs episodically, in limited regions, with less than 100 km of lateral motion accommodated along any particular boundary before plate motions cease. Europa may represent a world perched on the theoretical boundary between stagnant and mobile lid convective behavior, or it may represent an additional example of the wide variations in possible planetary convective regimes. Differences in observed strike‐slip sense and plate rotation directions between the northern and southern hemispheres raise the question of whether tidal forces may influence plate motions. Plain Language Summary 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 where there is evidence for surface motions like plate tectonics. This paper describes three areas on Europa where it appears that plate motions have occurred, and reconstructs what these areas looked like before the plates moved. Unlike the Earth, plate motions on Europa only happen in regional patches instead of covering the entire globe, and it appears that parts of Europa do not have plates. Also unlike the Earth, plate motions on Europa start and stop, and the plates only travel distances of less than a hundred kilometers before they come to a halt. Plate motions on Europa may be caused by heat‐driven motions in the warm