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EPRI/SOG Mmax Six earth-science teams, diverse methods largest observed eq (+ increment) catalog statistics – extreme oc

Figure A2-1. EPRI/SOG Mmax Six earth-science teams, diverse methods largest observed eq (+ increment) catalog statistics – extreme occurrences seismogenic feature: size, crustal setting, etc. extrapolate frequency-magnitude curve (e.g., the 1,000-year eq) global analogs

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EPRI/SOG Mmax Six earth-science teams, diverse methods largest observed eq (+ increment) catalog statistics – extreme oc

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  1. Figure A2-1 • EPRI/SOG Mmax • Six earth-science teams, diverse methods • largest observed eq (+ increment) • catalog statistics – extreme occurrences • seismogenic feature: size, crustal setting, etc. • extrapolate frequency-magnitude curve (e.g., the 1,000-year eq) • global analogs • saturation of mb scale • others … • Broad distributions reflect diverse methods & large uncertainties • Approximate center: mid-mb-5 (quiet sites), mid-mb-6 (active sites) • USGS Mmax • CEUS global analogs: stable continental regions (AJ), Bhuj • Craton: M 7.0 • Extended Margin: M 7.5 • Mmax distribution for 2008

  2. Figure A2-2

  3. USGS (margin) EPRI/SOG 4.5 5.0 5.5 6.0 6.5 7.0 7.5 Figure A2-3 Mmax (mb) EPRI/SOG and USGS Mmax distributions for South Texas Project site’s host source zones (original EPRI/SOG, not updated for 2006 Gulf of Mexico earthquakes)

  4. USGS (margin) EPRI/SOG 4.5 5.0 5.5 6.0 6.5 7.0 7.5 Figure A2-4 Mmax (mb) EPRI/SOG and USGS Mmax distributions for North Anna site’s host source zones

  5. Figure A2-5 Analysis • Develop alternative Mmax models that span those used in EPRI/SOG (and current PSHA practice) • Test Mmax models using USGS hazard model and computer codes • seismicity-based sources only (because they control the mid- to high-frequency hazard at many sites & Mmax is uncertain and controversial) • hold all parameters fixed except Mmax • Compare hazard results with current USGS model as ratio hazard maps and lists for selected sites • numerator: alternative Mmax / denominator: standard USGS Mmax • probabilistic ground motions for PGA, 5 Hz, 1 Hz • 2% probability of exceedance in 50 years

  6. Figure A2-6 Alternative Mmax Models • M5.0c5.5m • M 5.0 in craton, M 5.5 in margin • mb equivalent: 5.47c, 5.90m (AB95) or 5.27c, 5.67m (J96) • M6.0c6.5m • M 6.0 craton, M 6.5 margin • mb equivalent: 6.29c, 6.66m (AB95) or 6.04c, 6.40m (J96) • M7.0c7.5m • M 7.0 craton, M 7.5 margin • mb equivalent: 7.00c, 7.32m (AB95) or 6.74c, 7.07m (J96)

  7. North Anna M5.0c5.5m M5.0c5.5m M6.0c6.5m M6.0c6.5m M7.0c7.5m M7.0c7.5m mmax (mb) SouthTexas mmax (mb) Figure A2-7 4.5 5.0 5.5 6.0 6.5 7.0 7.5 Mmax (mb) 4.5 5.0 5.5 6.0 6.5 7.0 7.5 Mmax (mb)

  8. Figure A2-8 Hazard map (PGA, 2% prob of exc in 50 yrs): seismicity sources only, standard USGS Mmax (Prob of exc, px: probability of exceedance) Ratio hazard map (PGA, 2% prob of exc in 50 yrs): seismicity sources only / all sources Warm colors show where seismicity-based sources control hazard.

  9. 0.2-sec SA 1.0-sec SA Figure A2-9 Alternate Mmax model: M5.0c5.5m Ratio hazard maps (2% prob of exc in 50 yrs) M5.0c5.5m (sso) / standard USGS Mmax model (sso) (Prob of exc, px: probability of exceedance)

  10. 0.2-sec SA 1.0-sec SA Figure A2-10 Alternate Mmax model: M6.0c6.5m Ratio hazard maps (2% prob of exc in 50 yrs) M6.0c6.5m (sso) / standard USGS Mmax model (sso) (Prob of exc, px: probability of exceedance)

  11. 0.2-sec SA 1.0-sec SA Figure A2-11 Alternate Mmax model: M7.0c7.5m Ratio hazard maps (2% prob of exc in 50 yrs) M7.0c7.5m (sso) / standard USGS Mmax model (sso) (Prob of exc, px: probability of exceedance)

  12. Figure A2-12 Ratios of probabilistic ground motions (2% probability of exceedance in 50 yrs): Alternate Mmax (seismicity sources only) / USGS (seismicity sources only)

  13. 0.2-sec SA 1.0-sec SA Figure A2-13 Alternate Mmax model: M5.0c5.5m Ratio hazard maps (2% prob of exc in 50 yrs) Use M5.0c5.5m for numerator seismicity sources, but add the faults to both the numerator and denominator models (Prob of exc, px: probability of exceedance)

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