Larger aftershocks happen farther away: nonseparability of magnitude and spatial distributions of aftershocks

Geophysical Research Letters
By:  and 

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Abstract

Aftershocks may be driven by stress concentrations left by the main shock rupture or by elastic stress transfer to adjacent fault sections or strands. Aftershocks that occur within the initial rupture may be limited in size, because the scale of the stress concentrations should be smaller than the primary rupture itself. On the other hand, aftershocks that occur on adjacent fault segments outside the primary rupture may have no such size limitation. Here we use high-precision double-difference relocated earthquake catalogs to demonstrate that larger aftershocks occur farther away than smaller aftershocks, when measured from the centroid of early aftershock activity—a proxy for the initial rupture. Aftershocks as large as or larger than the initiating event nucleate almost exclusively in the outer regions of the aftershock zone. This observation is interpreted as a signature of elastic rebound in the earthquake catalog and can be used to improve forecasting of large aftershocks.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Larger aftershocks happen farther away: nonseparability of magnitude and spatial distributions of aftershocks
Series title Geophysical Research Letters
DOI 10.1002/2015GL064734
Volume 42
Issue 14
Year Published 2015
Language English
Publisher American Geophysical Union
Publisher location Washington, D.C.
Contributing office(s) Earthquake Science Center
Description 8 p.
First page 5771
Last page 5778
Online Only (Y/N) N
Additional Online Files (Y/N) N
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