provisions presentation - luco icc expo -...

9/2/2015

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New USGS Hazard Models& the NEHRP Design Maps

Nicolas LucoResearch Structural Engineer, USGS (Golden, CO)

BSSC PUC Design Mapping Issue Team (“IT‐11”)(Bachman, Crouse, Harris, Hooper, Kircher, Caldwell)

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

1) Guam & Tutuila in ASCE 7‐10

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1) USGS Hazard Model for Guam

1) USGS Hazard Model for Tutuila

1) Hazard Model Design Maps

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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

9080

70

6070 80

100

125

150

90

200

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

5060

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

OfuOlosega

Ta'u

Tutuila

Aunu'u

SwainsIsland

RoseAtoll

AmericanSamoa

172° 171° 170° 169° 168°

15°

14°

13°

12°

11°

15°

14°

13°

12°

11°

125

10090

8070

6050

40

35

30

60

50

40

2520

15

10

5

0.2 Second Spectral Response Acceleration (5% of Critical Damping)

OfuOlosega

Ta'u

Tutuila

Aunu'u

SwainsIsland

RoseAtoll

AmericanSamoa

172° 171° 170° 169° 168°

15°

14°

13°

12°

11°

15°

14°

13°

12°

11°

50

40

30

25

20

15

10

8

6

4

15

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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2) Ground Motions in 2009 Provisions

2) 2015 Provisions Ch. 22 CommentaryUNIFORM-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






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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 PEERReference: 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.

0 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)

Rat

io

Proposed ASCE/SEI 7-10Proposed Shahi & Baker

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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. …






4) Reasons for Updated Design Maps2) 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

100

101

0

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 [

Col

laps

e | S

A =

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)

Consultants2008‐2011

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)

PEER2010‐2013

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 on = 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


Total Population - S. California

RegionCity and Location of Site County or Metropolitan Statistical Area

9,948,081Los Angeles

No

rth

ern

Cal

iforn

iaS

ou

ther

n C

alifo

rnia

Total Population - N. California

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4) Changes at 34 High‐Risk Locations

Name Latitude Longitude Name PopulationRegion

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


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


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


Total Population - ID/UT/NV

Total Population - MO/TN/SC/IL/NY

CE

US

Oth

er

WU

SP

ac

ific

N

ort

hw

es

t

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 33 340.6

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 #

Pro

pos

ed

AS

CE

7-1

0 G

rou

nd

Mot

ion

Southern California Northern California PacNW IMW CEUS

SS (MCE

R)

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 33 340.6

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 #

Gro

un

d M

otio

n R

atio


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 33 340.6

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 #

Pro

pos

ed

AS

CE

7-1

0 G

rou

nd

Mot

ion


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 33 340.6

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 #

Pro

pos

ed

AS

CE

7-1

0 R

isk

Coe

ffic

ien

t


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 33 340.6

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 #

Pro

pos

ed

AS

CE

7-1

0 G

rou

nd

Mot

ion


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 EarthquakesFrom 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 other 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 33 340.6

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 #

Pro

pos

ed

AS

CE

7-1

0 S

ite

Coe

ffic

ien

t


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






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