The 1970’s were a strange time in America. Disaster movies were quite popular throughout the decade. Movies like Poseidon Adventure, Airport, and The Towering Inferno were well received by audiences and critics alike.
But no movie was stranger than Earthquake, which was shown with Sensurroud, a series of large speakers and a 1,500 watt amplifier, that would pump in sub-audible "infra bass" sound waves at 120 decibels (equivalent to a jet airplane at takeoff), giving the viewer the sensation of an earthquake.
The process of Sensurround was tested in several theaters around the United States prior to the film's release, yielding various results. A famous example is Grauman's Chinese Theater in Hollywood, California, where the "Sensurround" cracked the plaster in the ceiling. Ironically, the same theater premiered Earthquake three months later -- with a newly-installed net over the audience to catch any falling debris -- to tremendous success.
The "Sensurround" process proved to be a large audience draw, but not without generating a fair share of controversy. There were documented cases of nosebleeds generated by the sound waves. When the film premiered in Chicago, Illinois, the head of the building and safety department demanded the system be turned down, as he was afraid it would cause structural damage. In Billings, Montana, a knick-knack shop next door to a theater using the system lost part of its inventory when items from several shelves were thrown to the floor when the system was cued during the quake scenes. Perhaps the most amazing Sensurround incident occurred when a patron's ribs were cracked by the intense output of the system.