Table 5. Parameters for Finite Element Modelsa
Case Rate, mm/yr Viscosity,
Pa s Elastic Layer Thickness, km Youngâ€™s Modulus, GPa Width of Weak Zone, km chi2 chir2b
SAF LAF SW of SAF NE of SAF SW of SAF Weak Zone NE of Weak Zone
I c 34 0 4E19d 10d 8d 75 75 75 N/A 20.06 1.08
II e 36 0 3E19d 15 15 50d 30d 75 15d 14.77 0.82
IIIf 38-2+1.5 0 3E19-0.5E19+1.5E19 15 15 50d 40 +/- 5 75 15d 12.51 0.74
IVAg 34 3df 3E19d 10d 8d 75 75 75 N/A 10.83 0.60
IVBh 36-1.5+2 3 +/- 1 3E19-0.5E19+1.5E19 15 15 50d 40 +/- 8 75 25d 9.30 0.58
aFor all models, earthquake recurrence interval set to 205 years and the last earthquake set to 150 years ago. Estimated parameters are listed with plus/minus one standard deviation, as determined by equation (2), except as noted in footnote d. N/A denotes not applicable. SAF and LAF represent San Andreas Fault and Los Alamos Fault, respectively.
bReduced chi2, defined as chi2/N-p, where N is the number of data (22) and p is the number of adjusted parameter.
cLaterally uniform material properties, different elastic layer thickness on each side of fault, fixed SAF rate. Three adjusted parameters (Figures 13 and 14a).
dEstimated parameter, minimum misfit value reported. Significant trade off with other estimated parameters precludes meaningful uncertainty estimate. For the width of the weak zone, a minimum estimate is defined (~5 km smaller than listed value) but not a maximum estimate.
eLaterally uniform elastic layer thickness, different material properties on each side of fault, fixed SAF rate. Four adjusted parameters (Figures 14b and 16).
fSimilar to case II, with variable SAF rate. Five adjusted parameters (Figure 17).
gSimilar to case I, with variable LAF rate. Four adjusted parameters (Figure 19a).
hSimilar to cases II and III, with variable SAF and LAF rate. Six adjusted parameters (Figures 18 and 19b).
For cases IVA and IVB, LAF is modeled with an elastic half-space dislocation, with locking depth fixed at 10 km (case IVA) or 15 km (case IVB), and located 59 km SW of SAF.