The seismic waves from the Port Chicago explosion*

Abstract

Summary The records of the Port Chicago explosion alone suggest the conclusion that an averaged layering for California is 3 km. of rock of speed 5.0 km/sec. for longitudinal waves overlying a layer 11 km. thick of speed 5.6 km/sec., which in turn overlies a medium of speed 7.7 km/sec. No waves which traversed the mantle were observed. The root of the southern Sierra Nevada blocks the 7.7 km/sec. were even as it blocks the 8.0 km/sec. P normal waves. The air wave seems definitely recorded at Berkeley and Santa Clara as wave of period 3 or 4 seconds. The differential speed between the stations was normal, 342 m/sec. There is a suggestion of a short-period (0.5 sec.) air wave at Stanford with over-all speed of 333 m/sec. From study of the seismograms it is concluded that the energy in the earth waves was about 1016 ergs, or roughly of the order of one-thousandth of the probable energy released in the explosion.