Next Generation Attenuation (NGA) Projects Yousef Bozorgnia, Ph.D., P.E. Executive Director, Pacific Earthquake Engineering Research Center (PEER), University of California, Berkeley
NGA= Next Generation Attenuation Relation Three separate NGA projects: For active crustal EQs (like California, Middle East, Japan, Taiwan, ): NGA-West For subduction EQs (like Pacific Northwest and northern California, Japan, Chile, Peru, ): NGA-Sub Stable continental regions (like central & eastern US, a good portion of Europe, South Africa, ): NGA-East
NGA-West1 (Original NGA Project) Initiated October 2003 PEER compiled a very comprehensive database of ground motions recorded in shallow crustal earthquakes in active tectonic regions Numerous supporting research studies were also carried out
NGA-West1 In 2008, NGA ground motion prediction equations (GMPEs) were finalized USGS adopted the NGA-West1 GMPEs for the US National Seismic Hazard Maps NGA-West2 is a follow-up of NGA- West1
Sponsors of NGA-West2 Supports of the sponsors are appreciated
NGA-West2 Sub-Projects
Update worldwide database
Update worldwide database
Update worldwide database
Update worldwide database NGA-West2 database includes over 21,000 three-component recordings (over 63,000 records) From NGA-West1 to NGA-West2 the size of database was increased by a factor of 6
Examples of data added to NGA-West2 database Earthquake Name* Year M N Rec Rrup Range (km) Tottori, Japan 2000 6.61 414 1-333 Niigata, Japan 2004 6.63 530 8-300 Chuetsu-oki, Japan 2007 6.8 616 10-300 Iwate, Japan 2008 6.9 367 5-280 El Mayor-Cucapah, CA 2010 7.2 238 11-240 Darfield, New Zealand 2010 7 114 1-540 Christchurch, New Zealand 2011 6.1 104 2-440 Wenchuan, China 2008 7.9 263 1-1500 L'Aquila, Italy 2009 6.3 48 5-230 *subset of added events
Many NGA-West1 records were re-processed to widen the useable bandwidth Number of reliable longperiod records was increased by more than a factor of 2.5 Courtesy: Tim Ancheta
We added small magnitude data Database has 10,706 recordings associated with magnitude 4.5 Motivation: NGA-West1 models over-predicted motions for small magnitude In the future, we can analyze multiple events recorded at same site to characterize the site variability (single-station Sigma) In the regions that have mainly small magnitude data, they can compare NGA with their data
Magnitude scaling at small magnitude 10 0 PGA 10 0 SA(1.0s) Acceleration (g) 10-1 10-2 Rrup = 0 km Rrup = 10 km Rrup = 50 km Rrup = 200 km 10-1 10-2 10-3 10-3 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 Moment Magnitude 10-4 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 Moment Magnitude
V S30 distribution in database Measurements versus inferred values (estimated by various methods such as slop, geology, ) Courtesy: J. Stewart, E. Seyhan
V S30 distribution in database Measurements versus inferred values (estimated by various methods such as slop, geology, ) Courtesy: J. Stewart, E. Seyhan 16
Database flatfiles It has data (PGA, PGV, RotD50) and Metadata = Data about data
Database flatfiles Flatfiles are publically available at: http://peer.berkeley.edu/ngawest2/databases/ These are the files we used to develop GMPEs The flatfiles have response spectra There are 11 flatfiles available for 11 damping values
Public availability of NGA-West2 time series Actual time series ( time-histories ) will be downloaded from PEER web site Beta version of the online tool to select and download time series is being tested by a small group of users to test and find errors, typos Widespread version of the online database will be available in few weeks
NGA-West2 GMPEs for horizontal motion Using the latest database, and Using supporting research on: Directivity of ground motion HW/FW model using simulations data Update of nonlinear soil response New classification of main shock vs aftershocks
NGA-West2 GMPEs for horizontal motion Five teams of GMPE developers worked interactively and developed five GMPEs for horizontal components Abrahamson-Silva-Kamai (ASK team) Boore-Stewart-Seyhan-Atkinson (BSSA) Campbell-Bozorgnia (CB) Chiou-Youngs (CY) Idriss (I)
NGA-West2 GMPEs for horizontal motion Scope of horizontal GMPEs: RotD50 as the main intensity measure PGA, PGV, and spectral periods at least at 21 periods: 0.01, 0.02, 0.03, 0.05, 0.075, 0.1, 0.15, 0.2, 0.25, 0.3, 0.4, 0.5, 0.75, 1, 1.5, 2, 3, 4, 5, 7.5 and 10 sec No GMPE for PGD
NGA-West2 GMPEs for horizontal motion Scope of horizontal GMPEs: Applicable magnitude range: M 8.5 for strikeslip; M 8 for Reverse; M 7.5 for Normal faults Applicable distance range: 0-300 km If a GMPE developer team chooses different ranges, they have to provide reasoning GMPE developer teams can select a sub-set of the database, and provide reasoning for the selection
Example of comparison of horizontal GMPEs
Example of comparison of horizontal GMPEs 1 R JB =30, Strike-Slip, VS30=760 0.1 0.01 0.001 0.0001 ASK BSSA CB CY I 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 8.5 M
Example of changes since 2008 Reduced conservatism at small-moderate magnitude
Magnitude saturation at short periods is now a common feature Magnitude Saturation
Status of NGA-West2 GMPEs for Horizontal Motion
Status of Horizontal GMPEs PEER reports have been published and available free of charge to download Horizontal GMPEs were reviewed and adopted by the USGS for the 2014 National Seismic Hazard Maps Major impact on seismic design and evaluation of all facilities in the western US 29
Status of Horizontal GMPEs A collection of papers have been submitted and accepted by journal of Earthquake Spectra Accepted papers have been posted and can be downloaded from EERI web site Hard copy papers will be printed in August 2014 issue of EQS 30
Excel file of GMPEs There is an Excel file of the five GMPEs that you enter input parameters and it gives you weighted average of the prediction. Download it free of charge from: http://peer.berkeley.edu/ngawest2/databases/ 31
GMPEs for Vertical Ground Motion
NGA-West2 vertical GMPEs Four teams have completed development of GMPEs for vertical component: Gulerce-Kamai-Abrahamson-Silva (GKAS) Stewart-Seyhan-Boore-Atkinson (SSBA) Bozorgnia-Campbell (BC) Chiou-Youngs (CY)
Example of V/H spectra ratio 34
Status of NGA-West2 Vertical GMPEs A single PEER report, with different chapters documenting different vertical GMPEs, was published Journal papers to be submitted to Earthquake Spectra
Damping scaling of response spectra
Damping scaling of response spectra Scale GMPEs for damping other than 5%: 0.5% to 30% Ref: Rezaeian et al. (2012)
Damping scaling of response spectra A model was developed to scale spectral ordinates as a function of Damping ratio Magnitude Distance Damping Scaling Factors Ref: Rezaeian et al. (2012) Duration was important, but took care of the effects approximately through magnitude and distance Different models for horizontal and vertical components
Directivity Most NGA-West1&2 models have not explicitly included directivity of ground motion Five directivity models have been developed in NGA-West2 Wide-band and narrowband models This effort will continue in 2014 Latitude 35 34.5 34 1992 Landers, CA, EQ Lucerne Valley 136 cm/sec Rupture propagation Backward directivity region Forward directivity region Epicenter Joshua Tree 43 cm/sec -117-116.5-116 Longitude
Directionality (Polarization) NGA models are for average horizontal components Developed max and min rotated spectra, as a function of mag, distance, Examine relationship of max/min spectra with RotD50 (50 percentile) spectra Ref: Boore (2010)
Directionality key findings Only for the cases when the site is within 5 km of the fault and spectral period is longer than 0.5 sec, is the orientation of maximum rotated spectral ordinate is more likely to be closer to the strike-normal than the strike-parallel direction Beyond these ranges, the angle of the maximum rotated motion is random Ref: Shahi and Baker, PEER report 2013/10
Site Response NGA-West1 site amplification factors were inconsistent with NEHRP site amplification factors Goal: To make NEHRP and NGA site amplifications more consistent Proposed, and got major approval, to revise NEHRP factors
NGA-West2 Status All tasks and sub-projects completed on the proposed schedule 13 PEER reports have been published and can be downloaded free of charge from: http://peer.berkeley.edu/news/2013/05/ngawest2-flatfile-gmpes/ Database flatfiles have been made available to the public: http://peer.berkeley.edu/ngawest2/databases/
32 people have been involved in NGA- West2 Technical Coordination Committee: Abrahamson, Bozorgnia, Campbell External reviewers and oversight committee: Chris Wills, Mark Petersen, John Anderson, Roger Borcherdt, Silvia Mazzoni, Farzad Naeim Funding agencies representatives: Badie Rowshandel & Tom Shantz
32 people have been involved in NGA- West2 Database: Ancheta, Darragh, Chiou, Silva, Stewart, Seyhan, Graves, Wooddell, Katke, Boore, Kishida, Al Atik, NGA developers GMPE Developers: Abrahamson-Silva-Kamai Boore-Stewart-Seyhan-Atkinson Campbell-Bozorgnia Chiou-Youngs Idriss Damping: Rezaeian, Bozorgnia, Idriss, Abrahamson, Campbell, Silva & GMPE developers
32 people have been involved in NGA- West2 Vertical: GMPE developers Directivity: Spudich, Chiou, Baker, Shahi, Rowshandel, Somerville, Bayless, Watson- Lamprey & GMPE developers Directionality: Baker, Shahi, & directivity group Site Response: Stewart, Seyhan, Anderson, Borcherdt, Crouse, Graves, Idriss, Power, Silva, Shantz
NGA is about solving large complicated puzzle through collaboration and team-work NGA
NGA-Subduction 48
NGA-Subduction PEER has initiated a multidisciplinary multi-year research program to develop Next Generation Attenuation models for Subduction earthquakes: NGA-Sub We are in the middle of NGA-Sub So far the focus has been on development of the database
On-going efforts for subduction events data collection Japan, Taiwan, Solomon Islands, Cascadia, Mexico, Chile, Peru
Subduction events and recordings processed by PEER: Japan M # of Events # of Records > 7.5 11 3,800 6.5-7.5 41 20,000 < 6.5 32 13,000 Total 84 36,800
Subduction events and recordings processed by PEER: Chile M # of Events # of Records > 7.5 7 70 6.5-7.5 6 24 < 6.5 14 52 Total 27 146 For Chile, PEER also coordinated with USGS and surface-wave site measurements at 31 recording sites have been completed
NGA-Sub Plan Following completion of the database, Develop at least one GMPE for subduction If we can secure enough funding, the plan is to develop more than one GMPE Schedule: To complete by May 2016
NGA-East 54
NGA- East Goal: To develop next generation Ground Motion Prediction Equations (GMPEs) for Central & Eastern US Stable Continental Regions (SCRs) Sponsors: NRC, EPRI, USGS, DOE
NGA-East sub-projects Database: Compiled a database of recorded motions from Central Eastern North America (CENA) About 30,000 components have been processed Magnitude range: 2.7 to 6.9 Largest events: Nahanni 6.9, Saguenay 5.9, Mineral 5.7 Distance range: 0-1500 km
NGA-East sub-projects Geoetchnical Engineering: Linear and nonlinear site responses; reference rock condition; reference Kappa ; Source-Site Path: Investigate geometrical spreading (1/R, 1/R x ); Q; Regionalization of CENA, Ground Motion Simulation: Generate validated simulated GMs for CENA to be used by GMPE developers
NGA-East sub-projects GMPE Development scope Next generation attenuation models for CEUS; applicable to magnitude 4-8, distances of 0-1000 km 5% damped response spectra at periods 0.01 to 10 sec
NGA-East status Database has already been developed It is being QA d internally Regionalization efforts are completed Final report is being drafted Simulation validation has been completed Running simulations is started Complete the project by mid-2015 59
Thanks! Yousef@Berkeley.edu