Revisiting the 1894 Omori Aftershock Dataset with the Stretched Exponential Function

Research paper by Mignan, A.

Indexed on: 14 May '16Published on: 27 Apr '16Published in: Seismological Research Letters


In 1894, Fusakichi Omori published his landmark article on aftershocks in which he described the temporal decay rate of aftershocks as a power law. In this article, I show that the expression proposed by Omori does not hold when the proper visualization method is used (i.e., complementary cumulative density function in log–log plot) and that the choice of a stretched exponential function should have been preferred on physical grounds. I reproduce the emblematic aftershock sequence of the 1891 Great Nobi earthquake used by Omori and show that a stretched exponential expression describes the data better than a power law.