The problem you face is the success of science.You still have disproved the apparition. It would be interesting if you looked into it because I have of yet found a rational explanation except for talk that it is a UFO
If we lived in a world where as many planes were powered by prayre as by turbine engines, where religion was as good at offering up predictions as science, if science's window for explaining something was relatively small (ie. if something couldn't be explained in say 2 weeks it never would be)
Then any unexplained phenomena could be reasonably attributed to supernatural origin, unfortuneately for you we don't live in that world, planes built to supernatural specifications do not fly, and supernatural predictions invariably fail (end of the world anyone?).
Because of this, evidence for something supernatural has to be pretty impressive, it doesn't merely have to be unexplained it has to be fundamentally unexplainable. Fleeting glimpses of "something" that can be interpretted willy-nilly and that look suspiciously like tricks of light doesn't cut it.
50 feet high burning letters, that spell out the solution to quantum gravity, can be observed indefinatey to break almost every law of physics and induce a physiologically measureable feeling of happyness and well-being in anyone who observed said message, would cut it.
Given the success in explaining the other Mary mass sightings, it seems reasonable to suggest that this one like all the others has an explanation, the fact that seismic activity correlates well with the phenomena also seems to be a remarkable coincidence.
Why would God choose a sign, that looks so dubious? Why not the burning letters?