I've seen EARTHQUAKE 4 times for me in the Real SENSURROUND in February 1975 at the local ABC screen 1, for 79p was enough.
EARTHQUAKE returns to the Schauburg cinema Germany again! For 40th anniversary of, "An Event!"
The cinema is brining in a truck load of 21" subs.
they'll bring the house down or deafen the audience. 
Schauburg Celebrates Sensurround's 40th Anniversary and shows "Earthquake" in 70MM
http://www.in70mm.com/news/2014/sensurround/index.htm