Earthquake Sound Corp. Earthquake Sound, earthquake, earthquake speakers, subwoofers, car audio, subzero, magma, supernova, tnt amplifier, competition subs, sahyoun Earthquake Sound designs, manufactures, and markets high performance audio systems for use in home, automotive, and pro-sound audio systems. Earthquake Sound’s main headquarters are located in a 60,000 square foot facility in Hayward, California USA. Currently, Earthquake exports to over 50 countries worldwide and in 2010 opened a European warehouse in Denmark.