Autocorrelation of the Earth's Crust with Analog Computers

Abstract

Land-form geometry of the earth's ground surface, expressed statistically, finds application in both the civil and military phases of geology and engineering. To obtain statistics about the slope of the earth's crust, autocorrelation methods have been employed. Analog computers were used to compute the autocorrelation functions of terrain profile heights. Each profile was read out by a standard curve follower, the output was sampled by a commutator, and the autocorrelation values were registered in a bank of capacitors. This process required approximately 10 min per profile. For two sample profiles considered—one near Akron, Ohio and the other near Phoenix, Arizona—the mean values of the terrain heights were 1200 and 1570 ft, respectively; and the rms relief values were 71 and 263 ft, respectively.