| The surface of Europa is crosscut by a dense network of fractures and there are many candidate faults for studying past tectonic activity. To better understand the role of tidal stress sources and implications for faulting on Europa, we investigate the relationship between shear and normal stresses at four fault zones: Agenor Linea, Rhadamanthys Linea, Conamara Chaos (Agave/Asterius Linea), and Astypalaea Linea, offering a unique comparison of geological activity of fractures residing in geographically diverse locations of Europa. Assuming tidal diurnal and non-synchronous rotation (NSR) stresses are the primary mechanisms for strike-slip tectonism, here we investigate the mechanics of Coulomb shear failure on Europa. We consider a range of friction coefficients (microf = 0.2 - 0.6) and fault depths (0-6 km) to evaluate how the failure varies as a function of depth and its dependency on ice friction, geographic location, and fault geometry. Our results indicate that the conditions for failure are not met for any of the lineae subject to diurnal stresses only. Alternatively, models that include both diurnal and NSR stress readily generate shear and normal stress magnitudes that could give rise to shear failure. In general, failure seems to be confined to depths < 6 km for all four linea. Failure is easily activated and extends to depths ranging from 3-6 km on all four linea systems when a low coefficient of friction (microf = 0.2) is applied, but is generally limited to depths < 3 km when a high coefficient of friction (microf = 0.6) is applied. Based on these results, we infer that the conditions for shear failure are met along at least these four studied linea, and possibly others, on Europa when NSR is adopted as a driving stress mechanism. |
