Earthquakes, Aftershocks, and Total Energy

History demonstrates the great value of frequency domain data for understanding the physics of complex processes. The Cumulative Spectral Power (CSP) opens a new window into the study of earthquake evolution [2]. For this purpose, the CSP has a significant advantage over the Power Spectral Density (PSD) from which it is derived by integration. The FFT spectrum used to generate the PSD is inherently very noisy. An overlay of time-differing PSD curves on the same graph results in so much clutter that interpretation is very difficult. Because integration reduces the random noise of real world data, clutter is dramatically reduced when one does the same overlay using CSP data. As illustrated in Fig. 1 below, it is now possible to observe in a meaningful manner the evolutionary character of earthquakes and their aftershocks.