Skip to Main Content
Skip Nav Destination

Updated California aftershock parameters

Jeanne L. Hardebeck, Andrea L. Llenos, Andrew J. Michael, Morgan T. Page and Nicholas van der Elst
Updated California aftershock parameters
Seismological Research Letters (December 2018) 90 (1): 262-270


Reasenberg and Jones (1989) introduced a statistical model for aftershock rate following a mainshock along with estimates of "generic" California parameter values based on past aftershock sequences. The Reasenberg and Jones (1989) model has been used for decades to issue aftershock forecasts following M> or =5 mainshocks in California. Here, we update the "generic" parameters for California through a fit to the aftershock sequences of M> or =5 mainshocks occurring since 1980. We find aftershock productivity values that are lower on average than the generic productivity reported by Reasenberg and Jones (1989), likely because low-productivity sequences were omitted from their analysis and possibly because of a trade-off between productivity and b-value. We confirm the observation of Llenos and Michael (2017) that southern California sequences are more productive on average than northern California sequences. The Mendocino area is much less productive; the hydrothermal areas in Long Valley, Coso, and the Salton Sea, in contrast, are much more productive. We also quantify the variability of the Reasenberg and Jones (1989) productivity parameter a between sequences with a normal distribution. This distribution of a-values can be used to compute aftershock forecasts that include epistemic uncertainty and can be used as the prior for Bayesian updating of the a-value as a sequence progresses.

ISSN: 0895-0695
EISSN: 1938-2057
Serial Title: Seismological Research Letters
Serial Volume: 90
Serial Issue: 1
Title: Updated California aftershock parameters
Affiliation: U. S. Geological Survey, Menlo Park, CA, United States
Pages: 262-270
Published: 20181205
Text Language: English
Publisher: Seismological Society of America, El Cerrito, CA, United States
References: 25
Accession Number: 2019-002344
Categories: Seismology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables, sketch maps
N32°30'00" - N42°00'00", W124°30'00" - W114°15'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2022, American Geosciences Institute. Abstract, Copyright, Seismological Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201903
Program Name: USGSOPNon-USGS publications with USGS authors
Close Modal

or Create an Account

Close Modal
Close Modal