This is a companion to DOI:10.1029/2005JB003621.
Constraints on the size of the smallest triggering earthquake from the epidemic-type aftershock sequence model, Båth's law, and observed aftershock sequences
Article first published online: 6 AUG 2005
Copyright 2005 by the American Geophysical Union.
Journal of Geophysical Research: Solid Earth (1978–2012)
Volume 110, Issue B8, August 2005
How to Cite
2005), Constraints on the size of the smallest triggering earthquake from the epidemic-type aftershock sequence model, Båth's law, and observed aftershock sequences, J. Geophys. Res., 110, B08304, doi:10.1029/2004JB003535., and (
- Issue published online: 6 AUG 2005
- Article first published online: 6 AUG 2005
- Manuscript Accepted: 22 APR 2005
- Manuscript Revised: 12 APR 2005
- Manuscript Received: 11 NOV 2004
- earthquake triggering;
- statistical modeling of earthquakes
 The physics of earthquake triggering together with simple assumptions of self-similarity imply the existence of a minimum magnitude m0 below which earthquakes do not trigger other earthquakes. Noting that the magnitude md of completeness of a seismic catalog is not, in general, the same as the magnitude m0 of the smallest triggering earthquake, we compare observed aftershock sequence parameters with the predictions made by the epidemic-type aftershock sequence model to constrain the value of m0. In particular, we use quantitative fits to observed aftershock sequences from three previous studies, as well as Båth's law, to obtain four estimates of m0. We show that the branching ratio n (average number of triggered earthquakes per earthquake, also equal to the fraction of aftershocks in a seismic catalog) is the key parameter controlling the estimate of the minimum triggering magnitude m0. Conversely, physical upper bounds for m0 estimated from rate and state friction indicate that at the very least, 55% of all earthquakes are aftershocks.