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New USGS Hazard Models & the NEHRP Design Maps Nicolas Luco - - PDF document
New USGS Hazard Models & the NEHRP Design Maps Nicolas Luco - - PDF document
9/2/2015 New USGS Hazard Models & the NEHRP Design Maps Nicolas Luco Research Structural Engineer, USGS (Golden, CO) BSSC PUC Design Mapping Issue Team (IT 11) (Bachman, Crouse, Harris, Hooper, Kircher, Caldwell) Map Related
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1) MCER Maps for 2015 Provisions
13° 14° 15° 16° 13° 14° 15° 16°
Northern Mariana Islands Guam
200 150 125 100 90 80 70 6 70 8 100 125 150 90 2 200.2 250.6 288.6 243.9
0.2 Second Spectral Response Acceleration (5% of Critical Damping)
13° 14° 15° 16° 13° 14° 15° 16°
Northern Mariana Islands Guam
25 30 40 50 60 72.3
1.0 Second Spectral Response Acceleration (5% of Critical Damping)
. SS = 287%g . SS = 176%g . S1 = 72%g . S1 = 44%g
1) MCER Maps for 2015 Provisions
Ofu Olosega Ta'u Tutuila Aunu'u Swains Island Rose Atoll
American Samoa
172° 171° 170° 169° 168° 15° 14° 13° 12° 11° 15° 14° 13° 12° 11° 125 1 90 80 70 60 50 40 35 30 60 5 40 25 20 1 5 10 5
0.2 Second Spectral Response Acceleration (5% of Critical Damping) Ofu Olosega Ta'u Tutuila Aunu'u Swains Island Rose Atoll
American Samoa
172° 171° 170° 169° 168° 15° 14° 13° 12° 11° 15° 14° 13° 12° 11° 50 40 30 2 5 20 15 10 8 6 4 1 5 2 15
1.0 Second Spectral Response Acceleration (5% of Critical Damping)
. SS = 40%g . S1 = 15%g
1) 2015 Provisions Ch. 22 Commentary
… In comparing the MCER ground motion maps derived from these USGS hazard models to the geographically-constant values stipulated for Guam and American Samoa (Tutuila) in the 2010 and previous editions of ASCE/SEI 7, it is important to bear in mind that the latter were not computed via seismic hazard
- modeling. According to the commentary of the 1997 Provisions,
the geographically-constant values were merely conversions, via rough approximations, from values on the 1994 Provisions maps that had been in use for nearly 20 years. As such, they did not take into account the 1993 Guam earthquake that was the largest ever recorded in the region and caused considerable damage, the 2009 earthquake near American Samoa that caused a tsunami, nor the 2008 “Next Generation Attenuation (NGA)” and another 2006 empirical ground motion prediction equation that have now been used for both Guam/NMI and American Samoa. …
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Map‐Related Changes
1) New MCER, MCEG & Risk Coefficient maps for Guam, the Northern Mariana Islands, & American Samoa 2) Reference to underlying uniform‐hazard and deterministic ground motion maps & values on USGS website 3) Updated maximum‐response scale factors (Part 3) 4) Updated MCER, MCEG & Risk Coefficients maps for the conterminous US
2) Ground Motions in 2009 Provisions 2) 2015 Provisions Ch. 22 Commentary
UNIFORM-HAZARD AND DETERMINISTIC GROUND MOTION MAPS As alluded to above, implicit in the MCER ground motion, MCEG PGA, and risk coefficient maps provided are uniform-hazard (2%-in-50-years ground motion exceedance probability) and deterministic (84th percentile) ground motions. The 2009 Provisions provided maps of such uniform-hazard and deterministic ground motions, but ASCE/SEI 7-10 and the 2015 Provisions do not. Instead, uniform-hazard and deterministic ground motion maps consistent with this chapter are provided via a USGS website (http://earthquake.usgs.gov/hazards/designmaps/). Furthermore, values from these maps can be obtained via the ground motion software tool described above. …
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2) USGS Design Maps Web Tool 2) USGS Design Maps Web Tool Map‐Related Changes
1) New MCER, MCEG & Risk Coefficient maps for Guam, the Northern Mariana Islands, & American Samoa 2) Reference to underlying uniform‐hazard and deterministic ground motion maps & values on USGS website 3) Updated maximum‐response scale factors (Part 3) 4) Updated MCER, MCEG & Risk Coefficients maps for the conterminous US
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9/2/2015 6 3) Max‐Direction Factors in ASCE 7‐10
21.2 RISK-TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) GROUND MOTION HAZARD ANALYSIS … If the spectral response accelerations predicted by the attenuation relations do not represent the maximum response in the horizontal plane, then the response spectral accelerations computed from the hazard analysis shall be scaled by factors to increase the motions to the maximum
- response. If the attenuation relations predict the geometric mean or similar
metric of the two horizontal components, then the scale factors shall be: 1.1 for periods less than or equal to 0.2 sec; 1.3 for a period of 1.0 sec, and, 1.5 for periods greater than or equal to 5.0 sec, unless it can be shown that other scale factors more closely represent the maximum response, in the horizontal plane, to the geometric mean of the horizontal components. Scale factors between these periods shall be obtained by linear
- interpolation. …
3) Updated Factors from PEER
Reference: Shahi & Baker, 2013. “NGA‐West2 Models for Ground‐Motion Directionality,” PEER Report 2013/10.
SARotD100 SARotD50 SARotD100 SAGMRotI50
3) Proposed ÷ ASCE 7‐10 Factors
Conclusion: Incorporate updated factors into maps next cycle, concurrently with improvements to long‐period ground motions.
1 2 3 4 5 6 7 8 9 10 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5
Period (s) Ratio
Proposed ASCE/SEI 7-10 Proposed Shahi & Baker
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9/2/2015 7 3) Max‐Direction Factors in ASCE 7‐10
21.2 RISK-TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) GROUND MOTION HAZARD ANALYSIS … If the spectral response accelerations predicted by the attenuation relations do not represent the maximum response in the horizontal plane, then the response spectral accelerations computed from the hazard analysis shall be scaled by factors to increase the motions to the maximum
- response. If the attenuation relations predict the geometric mean or similar
metric of the two horizontal components, then the scale factors shall be: 1.1 for periods less than or equal to 0.2 sec; 1.3 for a period of 1.0 sec, and, 1.5 for periods greater than or equal to 5.0 sec, unless it can be shown that
- ther scale factors more closely represent the maximum response, in the
horizontal plane, to the geometric mean of the horizontal components. Scale factors between these periods shall be obtained by linear
- interpolation. …
Map‐Related Changes
1) New MCER, MCEG & Risk Coefficient maps for Guam, the Northern Mariana Islands, & American Samoa 2) Reference to underlying uniform‐hazard and deterministic ground motion maps & values on USGS website 3) Updated maximum‐response scale factors (Part 3) 4) Updated MCER, MCEG & Risk Coefficients maps for the conterminous US
4) Reasons for Updated Design Maps
2) Fragility curve = 0.8 = 0.6, for consistency with the site‐specific ground motion chapter (Ch. 21) of ASCE 7‐10 1) 2014 USGS National Seismic Hazard Model (including NGA‐West2, UCERF3, CEUS‐SSC)
10
- 1
10 10
1
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Spectral Acceleration (1.0 sec), a [g] P [ Collapse | SA = a ]
= 0.8 = 0.6
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4) USGS Hazard Model Updates
- See 10NCEE Paper 1698: Petersen et al, Updates for the
2014 National Seismic Hazard Maps: A summary of changes to seismic source and ground motion models, e.g., …
- Project Name
Lead(s) Duration Sponsors Central & Eastern US Seismic Source Characterization for Nuclear Facilities (CEUS‐SSC) Consultants 2008‐ 2011 US DOE, EPRI, US NRC Uniform California Earthquake Rupture Forecast, Version 3 (UCERF3) USGS, CGS, SCEC (WGCEP) 2010‐ 2013 CEA Next Generation Attenuation Relations for Western US, Version 2 (NGA‐West2) PEER 2010‐ 2013 CEA, Caltrans, PG&E
4) Fragility Update
- For 2009 NEHRP Provisions
MCER ground motions & site‐specific ground motion chapter (Ch. 21), the BSSC Seismic Design Procedures Reassessment Group settled
- n = 0.8
- For 2010 ASCE 7 Standard
- Ch. 21 (but not MCER maps),
the Seismic Subcommittee (SSC) Ad‐Hoc Ground Motion Committee updated to = 0.6, based on …
4) Changes at 34 High‐Risk Locations
Name Latitude Longitude Name Population Los Angeles 34.05
- 118.25
Century City 34.05
- 118.40
Northridge 34.20
- 118.55
Long Beach 33.80
- 118.20
Irvine 33.65
- 117.80
Orange 3,002,048 Riverside 33.95
- 117.40
Riverside 2,026,803 San Bernardino 34.10
- 117.30
San Bernardino 1,999,332 San Luis Obispo 35.30
- 120.65
San Luis Obispo 257,005 San Diego 32.70
- 117.15
San Diego 2,941,454 Santa Barbara 34.45
- 119.70
Santa Barbara 400,335 Ventura 34.30
- 119.30
Ventura 799,720 22,349,098 Population - 8 Counties 21,374,778 Oakland 37.80
- 122.25
Alameda 1,502,759 Concord 37.95
- 122.00
Contra Costa 955,810 Monterey 36.60
- 121.90
Monterey 421,333 Sacramento 38.60
- 121.50
Sacramento 1,233,449 San Francisco 37.75
- 122.40
San Francisco 776,733 San Mateo 37.55
- 122.30
San Mateo 741,444 San Jose 37.35
- 121.90
Santa Clara 1,802,328 Santa Cruz 36.95
- 122.05
Santa Cruz 275,359 Vallejo 38.10
- 122.25
Solano 423,473 Santa Rosa 38.45
- 122.70
Sonoma 489,290 14,108,451 Population - 10 Counties 8,621,978 Total Population - S. California Region City and Location of Site County or Metropolitan Statistical Area 9,948,081 Los Angeles
Northern California Southern California
Total Population - N. California
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9/2/2015 9 4) Changes at 34 High‐Risk Locations
Name Latitude Longitude Name Population Region City and Location of Site County or Metropolitan Statistical Area Seattle 47.60
- 122.30
King WA 1,826,732 Tacoma 47.25
- 122.45
Pierce WA 766,878 Everett 48.00
- 122.20
Snohomish WA 669,887 Portland 45.50
- 122.65
Portland Metro OR (3) 1,523,690 10,096,556 Population - 6 Counties 4,787,187 Salt Lake City 40.75
- 111.90
Salt Lake UT 978,701 Boise 43.60
- 116.20
Ada/Canyon ID (2) 532,337 Reno 39.55
- 119.80
Washoe NV 396,428 Las Vegas 36.20
- 115.15
Clarke NV 1,777,539 6,512,057 Population - 5 Counties 3,685,005
- St. Louis
38.60
- 90.20
- St. Louis MSA (16)
2,786,728 Memphis 35.15
- 90.05
Memphis MSA (8) 1,269,108 Charleston 32.80
- 79.95
Charleston MSA (3) 603,178 Chicago 41.85
- 87.65
Chicago MSA (7) 9,505,748 New York 40.75
- 74.00
New York MSA (23) 18,747,320 48,340,918 Population - 57 Counties 32,912,082 Total Population - ID/UT/NV Total Population - MO/TN/SC/IL/NY
CEUS Other WUS Pacific Northwest
Total Population - OR and WA
…
4) Changes in MCER & MCEG Values
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1718 19 20 21 22 23 24 25 2627 28 29 30 31 32 33 34 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 City Location # Proposed ASCE 7-10 Ground Motion Southern California Northern California PacNW IMW CEUS SS (MCER) S1 (MCER) PGA (MCEG) Santa Barbara Las Vegas Irvine San Diego Charleston
4) Previous Changes in MCE(R) Values
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1718 19 20 21 22 23 24 25 2627 28 29 30 31 32 33 34 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 City Location # Ground Motion Ratio Southern California Northern California PacNW IMW CEUS ASCE 7-10 ASCE 7-05 , SS ASCE 7-10 ASCE 7-05 , S1 ASCE 7-05 ASCE 7-98 , SS ASCE 7-05 ASCE 7-98 , S1
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4) Underlying Values
- As laid out in the 2009 NEHRP Provisions (& Ch. 21) …
4) Changes in USGS Unif.‐Hazard Values
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1718 19 20 21 22 23 24 25 2627 28 29 30 31 32 33 34 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 City Location # Proposed ASCE 7-10 Ground Motion Southern California Northern California PacNW IMW CEUS SSUH S1UH "PGAUH" Las Vegas Santa Barbara San Diego Charleston
4) Changes in Risk Coefficients
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1718 19 20 21 22 23 24 25 2627 28 29 30 31 32 33 34 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 City Location # Proposed ASCE 7-10 Risk Coefficient Southern California Northern California PacNW IMW CEUS CRS CR1
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4) Changes in Deterministic Values
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1718 19 20 21 22 23 24 25 2627 28 29 30 31 32 33 34 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 City Location # Proposed ASCE 7-10 Ground Motion Southern California Northern California PacNW IMW CEUS SSD S1D "PGAD"
4) Deterministic Earthquakes
- UCERF3 includes multi‐fault ruptures (M8+), in part to
remove UCERF2 overprediction of M6.5‐7 earthquakes.
4) Deterministic Earthquakes
- UCERF3 also includes low‐activity‐rate faults, e.g., …
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4) Deterministic Earthquakes
From ASCE 7‐10 site‐specific ground motion chapter (Ch. 21):
- For 2015 NEHRP Provisions,
characteristic earthquakes from UCERF2 (& ASCE 7‐10) have been updated and used in lieu of UCERF3 multi‐fault ruptures, and …
- “Active” faults have been
defined as those with Holocene (last ~12K years) displacement/slip, or with slip rate > 0.1 mm/year. All
- ther faults have been
excluded.
4) Changes in Site Coefficients
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1718 19 20 21 22 23 24 25 2627 28 29 30 31 32 33 34 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 City Location # Proposed ASCE 7-10 Site Coefficient Southern California Northern California PacNW IMW CEUS Fa Fv FPGA
4) Changes in Seismic Design Categories
SDC BC (Red) & CB (Blue) for Site Class D, Risk Category II
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4) Conclusions
- Amongst 34 high‐risk locations, 9/10‐ths of design map
changes are within +/‐20%, 2/3‐rds are within +/‐10%.
- Most of the >20% changes are due to significant USGS
hazard model updates.
- Some of the >20% changes are due to a compounding of
the USGS hazard model updates with the fragility update.
- Alone, the fragility update typically changes the design
maps by less than +/‐10%.
- Seismic Design Categories change in relatively small areas,
in some cases due to very small (0.001g) MCER changes.
4) Future Work – Project 17
- BSSC/FEMA‐USGS Collaboration; Planning committee
chaired by Ron Hamburger; Recommended issues are:
- Map precision vs. uncertainty and map stability
- The acceptable collapse risk that is targeted by the
design maps
- Ground motions for spectral periods other than 0.2s
& 1.0s, and Site Classes other than B, with due consideration of sedimentary basin effects
- Reassessment of deterministic ground motions