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WGCEP/NSHMP Fault Rupture Models

1. Type-B Faults MoRate from slip rate M char from M(A) 67% MoRate in M char (full fault ruptures) 33% MoRate in GR-Dist between M 6.5 and M char (higher M char ---> lower rates). WGCEP/NSHMP Fault Rupture Models. Type-A Faults

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WGCEP/NSHMP Fault Rupture Models

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  1. 1 • Type-B Faults • MoRate from slip rate • Mchar from M(A) • 67% MoRate in Mchar (full fault ruptures) • 33% MoRate in GR-Dist between M 6.5 and Mchar • (higherMchar ---> lower rates) WGCEP/NSHMP Fault Rupture Models Type-A Faults Segment & allow both single- and multi-segment ruptures Mrup from M(A); also gives implied ave slip Get rupture rates by satisfying slip rates and mean recurrence intervals

  2. 2 • If S segments, then R=S(S+1)/2 different ruptures involving contiguous segments. • We want the long-term rate (fr) of each rth rupture. • We know for each segment: Slip Rate (vs); Mean Recur Int (Ts=1/s) • Constraints are: • Equation Set (1) • Equation Set (2) • Equation Set (3) • Positivity • where Dsr is the average slip in the rth rupture on the sth segment, and Gsr is a matrix indicating whether the rth rupture involves the sth segment (1 if so, 0 if not). Type-A Fault Rupture Models

  3. 3 Adj Params (logic-tree Branches)

  4. 4 Using Ellsworth-B M(A):

  5. 5 Using Somerville (2006) M(A):

  6. Current WGCEP Solution 6 Ellsworth B M(A) & Tapered slip model:

  7. Current WGCEP Solution 7 Somerville M(A) & Tapered slip model:

  8. Define the following “a-priori” rupture rate models that solve (equation set 2): Current WGCEP Solution Minimum Rate Solution - That which minimizes the total rate of ruptures (and therefore maximizes event magnitudes), consistent with obs, and with branch weight of ~10%. Maximum Rate Solution - That which maximizes the total rate of ruptures (and therefore minimizes event magnitudes), consistent with obs, and with branch weight of ~10%. Geological Insight Solution(s) - Those that makes all fr as close as possible to preferred, complete sets defined by geologists, consistent with obs. (These don’t span solution space, but should span hazard/loss space?)

  9. Choose an “a-priori” rupture rate model that solves equation set (2) (min-rate, max-rate, or a geol-insight model) • Choose an assumed Dsr from the following: • Dsr = Ds(“Characteristic Slip”; e.g., WGCEP-1995) • Dsrproportional tovs(WGCEP-2002 Slip) • Dsr = Dr(Uniform/Boxcar) • Dsr- Tapered Ends (Elliptical) • If “Characteristic Slip” not chosen above, choose a Mag-Area Relationship: • Ellsworth A (WGCEP-2002) • Ellsworth B (WGCEP-2002) • Hanks and Bakun (2002) • Somerville (2006), which is ~ Wells & Coppersmith (1994) • Also choose: Deformation model; whether Aseismic Slip Factor reduces area or slip rate; and Gaussian-MFD sigma and trunc level (same for all ruptures) • Solve for final, moment-balanced rupture rates … Current WGCEP Solution

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