Scientific Reports 6: Article number: 21980; Published online: 26 February 2016; Updated: 13 May 2016

This Article contains errors in the Results section under subheading ‘Measurement of anisotropy and focal point’,

“The literature value41 for the SAW propagation velocity was fitted with a parabolic function 48 with the velocity v, the propagation angle ϕ towards the x direction and the anisotropy factor b. The parabolic fit leads to a theoretical value bfit = −0.228 (with dimensions of degree−2)”.

should read:

“The literature value41 for the SAW propagation velocity was fitted with a parabolic function 48 with the velocity v, the propagation angle ϕ (in radian) towards the x direction and the anisotropy factor b. The parabolic fit leads to a theoretical value bfit = −0.228 (b is dimensionless)”.