CyberShake Background Seismicity: Difference between revisions
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== UCERF2 == | == UCERF2 == | ||
To illustrate what events UCERF2 includes in background seismicity, below are plots of the magnitude-frequency distribution for the UCERF2 ERF in both linear and log scale. Blue is the full UCERF2 distribution, and black is the on-fault ERF used in CyberShake. All UCERF2 finite-fault ruptures are included in CyberShake, regardless of magnitude, though the GR distribution applied to type B faults is only for M>=6.5, and floating rupture sources start at M6.5, which is why there are fewer CyberShake events for M<6.5. | |||
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|[[File:ucerf2_mfd_linear.png|400px]] | |||
|[[File:ucerf2_mfd_log.png|400px]] | |||
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Calculation parameters: | Calculation parameters: | ||
Latest revision as of 19:34, 20 April 2020
Goal: determine the importance of background seismicity in different parts of CA to either validate it's exclusion in CyberShake or motivate an inclusion strategy.
UCERF2
To illustrate what events UCERF2 includes in background seismicity, below are plots of the magnitude-frequency distribution for the UCERF2 ERF in both linear and log scale. Blue is the full UCERF2 distribution, and black is the on-fault ERF used in CyberShake. All UCERF2 finite-fault ruptures are included in CyberShake, regardless of magnitude, though the GR distribution applied to type B faults is only for M>=6.5, and floating rupture sources start at M6.5, which is why there are fewer CyberShake events for M<6.5.
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Calculation parameters:
- GMPE: NGA-West2 GMPE (average of 4 models)
- ERF: UCERF2, with and without background seismicity
- Site Effects: Vs30 is from Wills (2015), no basin depth terms included
- IMT: 2 second SA.
| Model | 10% in 50yr | 2% in 50yr | 1% in 50yr |
|---|---|---|---|
| Excluding Background |  |
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| Including Background |  |
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| Ratio Exclude/Include |  |
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UCERF3
Calculation parameters:
- GMPE: NGA-West2 GMPE (average of 4 models)
- ERF: UCERF3, with the following configurations
- Supra-seismogenic ruptures only (only supra-seismogenic ruptures have finite fault surfaces in UCERF3, all others treated as gridded)
- Supra and Sub-seismogenic ruptures only (this adds gridded ruptures that correspond to sub-seimogenic ruptures on known faults)
- Supra, Sub-seismogenic, and off fault ruptures (complete model)
- Site Effects: Vs30 is from Wills (2015), no basin depth terms included
- IMT: 2 second SA.
| Model | 10% in 50yr | 2% in 50yr | 1% in 50yr |
|---|---|---|---|
| Supra-Seismogenic On-Fault Only |  |
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| Sub+Supra-Seismogenic On-Fault Only |  |
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| Complete Model (Supra+Sub+Off) |  |
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| Ratio Supra-Only/Complete |  |
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| Ratio Supra+Sub/Complete |  |
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