a) Visualization of the function M, evaluated for τ = 15 days close to the
Gran Canaria coast on the 15th April 2015 at 00:00 UTC. Superimposed, blue arrows
show the velocity field at that time, and the sinking point is also marked with a red
cross. The reattachment point and its stable manifold are also highlighted. Several
hyperbolic points are marked. The wild foldings of the unstable manifolds close to
the reattachment point are visible; b) time evolution of the green (modelled) and pink
(confirmed) spills on the 19th April 2015.