Observational Evidence for Earthquakes as a Nonlinear Dynamic Process

Yan Y. Kagan

Published October 1994, SCEC Contribution #106

Herein I review experimental evidence for earthquake scale-invariance. Earthquake occurrence exhibits scaling properties: the temporal correlations of earthquakes are power law and the distribution of the earthquake size is also a power law. Recently, it has been determined that several other statistical features of earthquakes, i.e., spatial distribution of earthquakes, rotation of their focal mechanisms, and stress patterns which both cause and are caused by earthquakes, are also scale-invariant. Seismicity is also recognized as a chaotic phenomenon. The intrinsic randomness of an earthquake occurence makes most of standard physical techniques unsuitable for study, thus the methods of stochastic processes should be used for the seismicity analysis. I present evidence that seismicity is controlled by scale-invariant statistical distributions which possibly have universal values for exponents. Finally, I discuss mechanical and other models proposed to reproduce these properties of seismicity, and offer a model of random defect interaction which, without additional assumptions, seems to explain most of the available empirical results.

Kagan, Y. Y. (1994). Observational Evidence for Earthquakes as a Nonlinear Dynamic Process. Physica D, 77(1-3), 160-192. doi: 10.1016/0167-2789(94)90132-5.