Why Would Europa Have Induced Magnetic Field?

Question

Other than suggested salty ocean beneath it's icy crust, what would possibly Europa has induced magnetic field which varies in direction and strength with Jupiter's strong magnetic field?

Answer 1

That really seem to be the only real idea behind it's induced magnetic field.

The magnetic field data from the Galileo orbiter showed that Europa has an induced magnetic field through interaction with Jupiter's, which suggests the presence of a subsurface conductive layer. The layer is likely a salty liquid water ocean. The crust is estimated to have undergone a shift of 80°, nearly flipping over (see true polar wander), which would be unlikely if the ice were solidly attached to the mantle. Europa probably contains a metallic iron core.  The Galileo orbiter found that Europa has a weak magnetic moment, which is induced by the varying part of the Jovian magnetic field. The field strength at the magnetic equator (about 120 nT) created by this magnetic moment is about one-sixth the strength of Ganymede's field and six times the value of Callisto's. The existence of the induced moment requires a layer of a highly electrically conductive material in the moon's interior. A likely candidate for this role is a large subsurface ocean of liquid saltwater.