The seismic noise of the earth's surface

Maximum, average, and minimum values of surface particle displacement, velocity, and acceleration of earth noise as a function of period are illustrated in graphical form. For periods less than about 5 seconds the amplitude curves rise rapidly with increasing period. The most prominent feature of the illustration is the sharp peak in the 5- to 8-second period range. There are virtually no data on noise in the range of periods between 20 seconds and the earth tide periods. With the exception of the 10- to 40-second period range, the data used are taken from the existing literature.