Abstract of the Results of the Investigation of the Charleston Earthquake ¹

Abstract

II. LET us suppose an elastic wave to originate at a point C (Fig. 1) situated at the depth q, below the surface. Let the intensity of the shock (amount of energy per unit of wave-front) at the distance unity from C, be denoted by a. Since the intensity is inversely proportional to the square of the distance, the intensity at the epicentrum would be (a/q² Take any other point on the surface of the earth at the distance x from the epicentre, and connect it with C by the line Cx=r. The intensity at any such point will obviously be equal to (a/r². If we denote the intensity by y, we shall then have the equation—