Open AccessStrike‐slip motion and double ridge formation on Europa
Author(s) -
Nimmo Francis,
Gaidos Eric
Publication year - 2002
Publication title -
journal of geophysical research: planets
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2000je001476
Subject(s) - geology , shear (geology) , shear zone , buoyancy , slip (aerodynamics) , shear velocity , crust , brittleness , seismology , geophysics , petrology , tectonics , mechanics , materials science , turbulence , physics , composite material , thermodynamics
There is abundant observational evidence for strike‐slip displacement on the surface of Europa. Strike‐slip motion between crustal blocks produces shear heating and an increase in temperature. We model the shear heating within the ice crust using a two‐dimensional, finite difference formulation, with a near‐surface brittle layer of constant specified thickness and a Newtonian ductile layer beneath. We obtain a maximum temperature anomaly of 66 K for a brittle layer thickness of 2 km and shear velocity of 6 × 10 −7 m s −1 . Such a velocity is appropriate for diurnal (85 hour) tidal motion. The local increase in temperature may cause ∼100 m uplift around the shear zone through thermal buoyancy. The stresses required to produce velocities of order 10 −7 m s −1 are similar to estimates for present‐day tidal stresses on Europa (10 4 –10 5 Pa). Brittle layer thicknesses >2 km are unlikely to persist at active shear zones because of the effect of shear heating. Shear velocities greater than or equal to ∼10 −6 m s −1 will give rise to melting at shallow depths. The removal of material by downwards percolation of meltwater may cause surface collapse along the shear zone; inward motion, leading to compression, may also result. The combination of thermally or compression‐induced uplift and melt‐related collapse may be responsible for the pervasive double ridges seen on Europa's surface.