If the tectonic strain theory for luminous phenomena be correct, then significant electromagnetic emissions and radon gas release should occur in focal regions in which people report an alleged "UFO flap." Considering the epidemiological evidence that these stimuli might promote the incidence of brain tumors, their occurrence during the 5 years before and the 5 years after the November, 1975 episode of multiple luminous displays within the Sudbury Basin (Canada) was examined. Compared to the adjacent control area, there was a significant increase in brain tumors after the episode for men (conservative odds ratio = 2.5) but not for women; however, the magnitude was well within the expected range of incidence within the general population. Such changes have theoretical implication but may have little clinical or health significance.