Imaging the earthquake cycle with the Moment-Ratio Method: An exploration

Abstract

The seismic moment cycle at plate boundaries may be imaged by the Moment–Ratio Method (MRM). In this exploratory technique the fluctuation of cumulative moment deficiency is used as an indicator of the cycle of degradation and recovery of free energy along an active tectonic region. A 20–year half–life is assumed for the healing process of earthquake ruptures along the Pacific plate boundary. Using the Pacheco–Sykes Catalog of large shallow earthquakes (M>7), we estimate the moment ratio for Japan and Mexico at 20–year intervals during the 20^th century. Moment–ratio peaks for 1980 correlate with subsequent earthquakes of magnitude M>7 during the following 20–year period in Mexico and Japan.