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Magnitude conversion of earthquake rate forecasts

David A. Rhoades and Annemarie Christophersen
Magnitude conversion of earthquake rate forecasts
Bulletin of the Seismological Society of America (December 2017) 107 (6): 3037-3043

Abstract

Regional earthquake catalogs typically report local magnitudes for most earthquakes. Moment magnitudes, which are commonly used in ground-motion modeling, are available generally only for larger earthquakes. Earthquake rate forecasts based on local magnitudes must be converted to moment magnitudes for use in earthquake hazard studies. Here, we describe several approximate methods of carrying out the conversion, based on a regression of moment magnitude on local magnitude and its associated uncertainties. They apply to gridded forecasts in the style of regional earthquake likelihood models. The methods vary greatly in computational efficiency, but provide similar results. The simplest method applies a multiplier to the rate in each magnitude bin and spatial cell, assuming that the earthquake rate versus magnitude relation has a Gutenberg-Richter b-value of 1. This method has been used to convert earthquake forecasts disseminated during the Canterbury and Kaikoura earthquake sequences in New Zealand to moment magnitude.


ISSN: 0037-1106
EISSN: 1943-3573
Coden: BSSAAP
Serial Title: Bulletin of the Seismological Society of America
Serial Volume: 107
Serial Issue: 6
Title: Magnitude conversion of earthquake rate forecasts
Affiliation: GNS Science, Lower Hutt, New Zealand
Pages: 3037-3043
Published: 201712
Text Language: English
Publisher: Seismological Society of America, Berkeley, CA, United States
References: 24
Accession Number: 2018-031684
Categories: Seismology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table
S44°57'00" - S41°47'60", E168°46'00" - E173°28'00"
S42°34'60" - S41°40'00", E173°00'00" - E174°04'60"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute. Abstract, Copyright, Seismological Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 2018
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