Moho‐offset beneath northern Scotland

Summary. Independent sets of LISPB data are presented, having as a common feature a local lateral variation in the Moho beneath northern Britain. The evidence for this step‐like feature on the Moho is taken from P and S travel times and from PS reflection times and phase velocities. Another important observation is that a high‐frequency Moho refraction is generated north of the step, whilst the refraction from the step region and south of it contains only low frequencies. This leads to the assumption that a change in the Moho structure exists in the same region as where the step has been deduced from travel‐time interpretation. A numerical model is presented which generates a high‐frequency refracted wave from an input signal which contains low‐ and high‐frequency spectral energy. The significance of this offset on the Moho, in particular its relationship to surface tectonics, is critically discussed.