The statistical properties of the radial propagation of ELMs have been investigated in the Scrape-Off-Layer (SOL) region of the JET tokamak. The shape of ELMs shows evidence of fine high frequency structures propagating radially with effective radial velocities in the range of 1000 m/s. Experimental results suggest a link between the radial velocity and the size of transport events. This shows the importance of the competition between both parallel and radial transport to explain particle losses onto the divertor plates. Parallel flows show a transient increase during the appearance of ELMs, providing evidence of a coupling between parallel dynamics and radial transport.