AIA 335 and 171 Å EUV running-difference images showing the propagation of EUV waves on 25 March 2011. “F” and “S” indicate the faster and slower wavefronts, respectively. The slices selected for the space-time intensity plots are marked by “S1” to “S5” (top-right). “F1” and “F2” also represent the fast wavefronts, while “T” shows the transmitted wavefront from AR NOAA 11177. X and Y axes are given in arcsecs.