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Calculating California Seismicity Rates

Open-File Report 2007-1437-I

Prepared in cooperation with the California Geological Survey and the Southern California Earthquake Center
By:

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Abstract

Empirically the rate of earthquakes = magnitude M is well fit by the Gutenberg-Richter relationship, logN=a-bM (1) where N is the number of earthquakes = M over a given time period, a is the number of M = 0 earthquakes over the same period, and b is a parameter that determines the ratio of larger to smaller earthquakes (Ishimoto and Iida 1939; Gutenberg and Richter 1944). Thus to characterize the seismicity rate, N, and risk in a given region we need to solve for the values of a and b. Here we are concerned with solving for the long term average values of these parameters for the state of California. My primary data source is a catalog of 1850-2006 M = 4.0 seismicity compiled with Tianqing Cao (Appendix H). Because earthquakes outside of the state can influence California I consider both earthquakes within the state and within 100 km of the state border (Figure 1).

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Calculating California Seismicity Rates
Series title:
Open-File Report
Series number:
2007-1437
Chapter:
I
Edition:
Version 1.0
Year Published:
2008
Language:
ENGLISH
Publisher:
Geological Survey (U.S.)
Contributing office(s):
Earthquake Hazards Program
Description:
iii, 41 p.
Larger Work Type:
Report
Larger Work Subtype:
USGS Numbered Series
Larger Work Title:
Appendix I in The Uniform California Earthquake Rupture Forecast, Version 2 (UCERF 2)