Decustering , Rates, and b -values or Declustering : the Necessary Evil of Statistical Seismology
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Decustering, Rates, and b-values or ustering: the Necessary Evil of Statistical Seismol Andy Michael
description
Decustering , Rates, and b -values or Declustering : the Necessary Evil of Statistical Seismology. Andy Michael. Gardner and Knopoff Declustering. Method: Gardner and Knopoff (BSSA, 1974): Magnitude-dependent spatial circles and time windows - PowerPoint PPT Presentation
Transcript of Decustering , Rates, and b -values or Declustering : the Necessary Evil of Statistical Seismology
Decustering, Rates, and b-valuesor
Declustering: the Necessary Evil of Statistical Seismology
Andy Michael
Gardner and Knopoff DeclusteringMethod:
Gardner and Knopoff (BSSA, 1974):Magnitude-dependent spatial circles and time windows
Problem: Spatial circles too small for large earthquakesSolution: Use radii based on fault rupture lengths from
Wells and Coppersmith (BSSA, 1994)
Christophersen et al. Declustering Radii Choices
SCSN M≥2 1984-2010 Radii = Uhrhammer ΔT = 1 day
Nmain=32490, p=0
SCSN M≥2 1984-2010 Radii = G-K ΔT = 1 day
Nmain=26992, p=3*10^-7
SCSN M≥2 1984-2010 Radii = G-K ΔT = 3 days
Nmain=19494, p=0.002
SCSN M≥2 1984-2010 Radii = G-K ΔT = 7 days
Nmain=12892, p=0.56
SCSN M≥2 1984-2010 Radii = G-K ΔT = 100 days
Nmain=1185, p=0.89
N=79661
N=13529
N=8124
Issues for UCERF3:Decluster and then estimate rates orEstimate rates using an ETAS model directly.
If declustering then which method or how many methods?
National Maps use Gardner-Knopoff which lowers b-valueETAS uses the same b-value for background and clusters
Could decluster with a stochastic ETAS approach and maintainthe same b-value, good for ETAS but bad for National Maps
Could decluster with Gardner-Knopoff and then do ETASwith a different magnitude-frequency distributionthat combines to the correct total distribution.
