10:15 AM - 10:30 AM
[SSS30-06] Fractal fault zone geometry and scale-dependent static stress drop
Keywords:static stress drop, scale dependence, fault zone geometry, hierarchically selfsimilar
Key Point 1
If Davof a fault (L, Dmax) is πDmax/4, ∆σ = CπDmax/4L.
For a fault composed of linked n faults with (L/n, Dmax) also Dav = πDmax/4, while ∆σ = nCπDmax/4L.
[Symbol fault length:L, maximum slip:Dmax and averaged slip:Dav, static stress drop:∆σ, proportional constant:C]
Key Point 2
Slip distributions Dx on fault segments are approximated by two simple cases below.
Cases of homogeneous frictional resistance Dx = 2(1 - ν)/G × (σyxr - σyxc) × (a2 - x2)0.5.
Cases of frictional resistance with a linear gradient Dx = (1 - ν)/G × (2σyxr - σyxc(x/a)) × (a2 - x2)0.5.
[Symbol half length of fault segments:a, Poisson's ratio:ν, remote stress:σxyr, frictional resistance:σxyc]
Key Point 3
When Ls(i,j) < Ws, ∆σav(i,j) = (7πG/8)(Dav(i,j)/Ls(i,j).
When Ls(i,j) > Ws, ∆σav(i,j) = (2G/π)(Dav (i,j)/Ws.
The static stress drops averaged over the whole fault length L0 is ∆σ = (∑∆σav(i,j)Ls(i,j)/L0.
[Symbol for j-th segment of hierarchical rank i, segment length:Ls(i,j), averaged slip:Dav(i,j), static stress drop:∆σav(i,j), thickness of seismogenic crustal layer:Ws, rigidity:G]
Analytical Results
17 among 21 data are approximated to the equation below (Fig.1c).
∆σ = 79.0 L0-0.519 (units km and MPa)