Well they should, but legally according to the aviation regulations, volcanos are something which airlines are not responsible for, and don´t have any obligation to accept or compensate passengers for it.

Er – no. Airlines don’t have to compensate passengers, but they do have an obligation to feed & accommodate them while they are delayed. Ryanair accepted that (after consulting its lawyers), & put a notice on its website saying so, & quoting the relevant regulations. A link to it was posted on this forum a few weeks ago.

This fine is for Ryanair failing to do what it agreed it was legally required to do, & promised to do.