Flashes and vibrations caused by a refinery in Vitrolles, 1981

Summary

In January 1981 several witnesses near Vitrolles reported a deep sound and noticeable vibrations during the early hours, along with pinkish flashes in the sky above a factory. The investigation determined the phenomenon was caused by the start-up of a new installation at a local refinery: a flare tower lit that night produced the lights reflected in the clouds. Case resolved with a technical explanation.