EERI Seminar on Next Generation Attenuation Models Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions Building Seismic Safety Council (BSSC) Webinar Nicolas Luco Research Structural Engineer, USGS (Golden, CO) BSSC PUC Design Mapping Issue Team (“IT-11”) (Bachman, Crouse, Harris, Hooper, Kircher, Caldwell)

EERI Seminar on Next Generation Attenuation Models ASCE/SEI 7-10 Ground-Motion Maps “New USGS Seismic Hazard Models & their Impacts on ASCE/SEI 7-16,” N. Luco (USGS) et al February 16, 2016 Building Seismic Safety Council (BSSC) Webinar Risk Target = 1% Probability of Collapse in 50 years Maximum-direction spectral response accelerations Deterministic caps FIGURE 22-1/2RISK-TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCE R ) … SPECTRAL RESPONSE ACCELERATION …, SITE CLASS B

EERI Seminar on Next Generation Attenuation Models ASCE/SEI 7-10 Ground-Motion Maps “Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions,” N. Luco (USGS) et al March 22, 2016 FIGURE 22-7 MAXIMUM CONSIDERED EARTHQUAKE GEOMETRIC MEAN (MCE G ) PGA …, SITE CLASS B … Building Seismic Safety Council (BSSC) Webinar Uniform-Hazard, 2% Probability of Exceedance in 50 years Geometric mean PGA across two horizontal components Deterministic caps

EERI Seminar on Next Generation Attenuation Models Outline of this presentation “Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions,” N. Luco (USGS) et al March 22, 2016 Building Seismic Safety Council (BSSC) Webinar Updates to MCE R (& MCE G ) maps for conterminous US for 2015 NEHRP Provisions Comparisons with values from ASCE 7-10 Comparisons with previous editions of ASCE 7-05 and ASCE 7-02/7-98 Summary Updated USGS Seismic Design Maps web tool Status of adoption into ASCE 7-16, IBC, IRC

EERI Seminar on Next Generation Attenuation Models 2) Fragility curve  = 0.8   = 0.6, for consistency with the site- specific ground motion chapter (Ch. 21) of ASCE 7-10 Reasons for Updated Design Maps 1)2014 USGS National Seismic Hazard Model (including NGA- West2, UCERF3, CEUS-SSC) “Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions,” N. Luco (USGS) et al March 22, 2016 Building Seismic Safety Council (BSSC) Webinar

EERI Seminar on Next Generation Attenuation Models USGS Hazard Model Updates “Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions,” N. Luco (USGS) et al March 22, 2016 Building Seismic Safety Council (BSSC) Webinar Others listed in Chapter 22 Commentary and explained in December 2015 Special Issue of Earthquake Spectra journal Project NameLead(s)DurationSponsors Central & Eastern US Seismic Source Characterization for Nuclear Facilities (CEUS-SSC) Consultants US DOE, EPRI, US NRC Uniform California Earthquake Rupture Forecast, Version 3 (UCERF3) USGS, CGS, SCEC (WGCEP) CEA Next Generation Attenuation Relations for Western US, Version 2 (NGA-West2) PEER CEA, Caltrans, PG&E

EERI Seminar on Next Generation Attenuation Models Fragility    Update “Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions,” N. Luco (USGS) et al March 22, 2016 Building Seismic Safety Council (BSSC) Webinar For 2009 NEHRP Provisions MCE R 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 MCE R maps), the Seismic Subcommittee (SSC) Ad-Hoc Ground Motion Committee updated to  = 0.6, based on …

EERI Seminar on Next Generation Attenuation Models Changes at 34 High-Risk Locations “Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions,” N. Luco (USGS) et al March 22, 2016 Building Seismic Safety Council (BSSC) Webinar …

EERI Seminar on Next Generation Attenuation Models Changes at 34 High-Risk Locations “Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions,” N. Luco (USGS) et al March 22, 2016 Building Seismic Safety Council (BSSC) Webinar …

EERI Seminar on Next Generation Attenuation Models “Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions,” N. Luco (USGS) et al March 22, City Locations from 2009 Provisions Building Seismic Safety Council (BSSC) Webinar

EERI Seminar on Next Generation Attenuation Models Changes in MCE R & MCE G Values “Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions,” N. Luco (USGS) et al March 22, 2016 Building Seismic Safety Council (BSSC) Webinar Santa Barbara Las Vegas Irvine San Diego Charleston

EERI Seminar on Next Generation Attenuation Models Underlying Components of S S and S 1 “Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions,” N. Luco (USGS) et al March 22, 2016 Building Seismic Safety Council (BSSC) Webinar As laid out in the 2009 NEHRP Provisions (& Ch. 21) … … S S = min( C RS S SUH, S SD ) S 1 = min( C R1 S 1UH, S 1D )

EERI Seminar on Next Generation Attenuation Models Changes in USGS Uniform-Hazard Values “Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions,” N. Luco (USGS) et al March 22, 2016 Building Seismic Safety Council (BSSC) Webinar Las Vegas Santa Barbara San Diego

EERI Seminar on Next Generation Attenuation Models Changes at Las Vegas Location “Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions,” N. Luco (USGS) et al March 22, 2016 Building Seismic Safety Council (BSSC) Webinar In ASCE 7-10 maps, rate of earthquakes on Eglington fault is ~1/14,000yrs. Based on recent publications (references in dePolo et al, 2013), … Nevada Bureau of Mines & Geology recommended, in effect, a rate of ~1/600yrs. Through additional communication with USGS, all agreed on ~1/2,100yrs.

EERI Seminar on Next Generation Attenuation Models Changes at Santa Barbara Location “Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions,” N. Luco (USGS) et al March 22, 2016 Building Seismic Safety Council (BSSC) Webinar

EERI Seminar on Next Generation Attenuation Models Changes at Santa Barbara Location “Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions,” N. Luco (USGS) et al March 22, 2016 Building Seismic Safety Council (BSSC) Webinar ASCE 7-10 maps are based on UCERF2 in California. UCERF3 includes more multi-fault earthquakes (like 2011 M7.2 El Mayor- Cucapah), in part to remove UCERF2 over-prediction of M6.5-7 earthquakes. This, in effect, lowers rate of earthquakes that dominate hazard in Santa Barbara. ASCE 7-10 maps are based on NGA-West1 for Western U.S. crustal earthquakes. NGA-West2 includes recent data from 2009 M6.3 L’Aquila, 2008 M7.9 Wenchuan & 5 other earthquakes on dipping faults, as well as 130,000 ground motion simulations. The effect was to decrease best estimates of ground motions over reverse faults near Santa Barbara.

EERI Seminar on Next Generation Attenuation Models Commentary on Additional Changes “Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions,” N. Luco (USGS) et al March 22, 2016 Building Seismic Safety Council (BSSC) Webinar

EERI Seminar on Next Generation Attenuation Models Changes in Risk Coefficients “Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions,” N. Luco (USGS) et al March 22, 2016 Building Seismic Safety Council (BSSC) Webinar

EERI Seminar on Next Generation Attenuation Models Changes in Deterministic Values “Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions,” N. Luco (USGS) et al March 22, 2016 Building Seismic Safety Council (BSSC) Webinar

EERI Seminar on Next Generation Attenuation Models UCERF3 includes multi-fault ruptures (M8+), in part to remove UCERF2 overprediction of M6.5-7 earthquakes. Deterministic Earthquakes “Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions,” N. Luco (USGS) et al March 22, 2016 Building Seismic Safety Council (BSSC) Webinar

EERI Seminar on Next Generation Attenuation Models UCERF3 also includes low-activity-rate faults, e.g., … Deterministic Earthquakes “Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions,” N. Luco (USGS) et al March 22, 2016 Building Seismic Safety Council (BSSC) Webinar

EERI Seminar on Next Generation Attenuation Models From ASCE 7-10 site-specific ground motion chapter (Ch. 21): Deterministic Earthquakes “Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions,” N. Luco (USGS) et al March 22, 2016 Building Seismic Safety Council (BSSC) Webinar 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.

EERI Seminar on Next Generation Attenuation Models Previous Changes in MCE (R) Values “Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions,” N. Luco (USGS) et al March 22, 2016 Building Seismic Safety Council (BSSC) Webinar

Precision vs. Uncertainty

EERI Seminar on Next Generation Attenuation Models Comment from ASCE 7-16 Main Committee “Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions,” N. Luco (USGS) et al March 22, 2016 Building Seismic Safety Council (BSSC) Webinar “These maps continue to change both up and down each cycle which is causing a lack of confidence in them by the design community. The maps need to stabilize for a few cycles for the users of the standard to develop confidence in them. I would recommend that we stay with the current maps.” Three other Main Committee members made similar (but longer) comments.

Precision vs. Uncertainty

EERI Seminar on Next Generation Attenuation Models Summary “Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions,” N. Luco (USGS) et al March 22, 2016 Building Seismic Safety Council (BSSC) Webinar Conterminous US updates include (i) 2014 USGS NSHM, (ii)  =0.6, and (iii) definition of “active faults” for deterministic ground motions. 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. Seismic Design Categories change in relatively small areas, mostly at relatively low-risk locations. Uncertainty in design ground motions desired for perspective.

EERI Seminar on Next Generation Attenuation Models Deeper Explanations of Changes “Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions,” N. Luco (USGS) et al March 22, 2016 Building Seismic Safety Council (BSSC) Webinar

EERI Seminar on Next Generation Attenuation Models Updated Design Maps Web Tool “Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions,” N. Luco (USGS) et al March 22, 2016 Building Seismic Safety Council (BSSC) Webinar

EERI Seminar on Next Generation Attenuation Models Updated Design Maps Web Tool “Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions,” N. Luco (USGS) et al March 22, 2016 Building Seismic Safety Council (BSSC) Webinar

EERI Seminar on Next Generation Attenuation Models Updated Design Maps Web Tool “Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions,” N. Luco (USGS) et al March 22, 2016 Building Seismic Safety Council (BSSC) Webinar

EERI Seminar on Next Generation Attenuation Models Updated Design Maps Web Tool “Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions,” N. Luco (USGS) et al March 22, 2016 Building Seismic Safety Council (BSSC) Webinar

EERI Seminar on Next Generation Attenuation Models Updated Design Maps Web Tool “Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions,” N. Luco (USGS) et al March 22, 2016 Building Seismic Safety Council (BSSC) Webinar

EERI Seminar on Next Generation Attenuation Models Updated Design Maps Web Tool “Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions,” N. Luco (USGS) et al March 22, 2016 Building Seismic Safety Council (BSSC) Webinar

EERI Seminar on Next Generation Attenuation Models Updated Design Maps Web Tool “Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions,” N. Luco (USGS) et al March 22, 2016 Building Seismic Safety Council (BSSC) Webinar

EERI Seminar on Next Generation Attenuation Models Status of Adoption for ASCE 7-16, etc. “Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions,” N. Luco (USGS) et al March 22, 2016 Building Seismic Safety Council (BSSC) Webinar After initially being rejected, the updated maps are one editorial step away from adoption into ASCE 7-16 The updated maps have been proposed for the International Building Code (IBC) An alternate IBC proposal would simply reference ASCE 7-16 Corresponding Seismic Design Category maps have been proposed for the International Residential Code