Track A2: "Motion of the phonograph arm is not necessarily identical with original earth motion, is more than occurred at Pasadena; however motion originated from direct amplification of original tape signals. Any audible sound here will be from the skipping of grooves by the arm and cartridge" and "Skipping is intentional and indigenous to the nature of the subject matter."

Side A recorded at Pasadena.

Shocks in order of occurence on Side A: 1. San Clemente Island (Off California Coast), December 26, 1951; tape speed x750; magnitude 5.75*; 2. Aftershocks Of Destructive Arvin-Tehachapi Earthquake, Kern Co., California (Bakersfield, Et Al.), July 21, 1952; magnitude 7.75*; speed x750; 3. Epicenter Indian Ocean About 900 Miles S.E. Madagascar, December 8, 1951; magnitude 7.75*; speed x750; 4. Small California Quake With Three Aftershocks, June 25, 1951; magnitude 4.6*; speed x750, x375, x187; 5. Oxaca, Mexico, December 12, 1951; magnitude 7*; speed x750; 6. 1 Repeated; 7. Hawaii, August 21, 1951; magnitude 6.75*; x750; 8. 1 and 7 x750; 9. 1, 7 and 3 x750; 10. 1, 7 and 3) x375.

The number 13 in the title of track B4.2 refers to track B4.1.