Recent Advances in
Development of Ground
Motion Prediction Equations
Yousef Bozorgnia, Ph.D., P.E.
Executive Director,
Pacific Earthquake Engineering
Research Center (PEER),
University of California, Berkeley

Ground Motion “Mega” Research
Projects at PEER

NGA-West2

NGA-East

Ground motion hazard in low seismicity
regions

NGA-Sub

Ground motion hazard in active tectonicregions

Ground motion hazard in Subduction regions

GEM Global Earthquake ModelNGA-West2
Next Generation
Attenuation (NGA) Models
for Shallow Crustal
Earthquakes in Active
Tectonic Regions

NGA-West1

NGA-West1 (Original NGA Project)
 PEER compiled a very comprehensive

database of ground motions recorded inshallow crustal earthquakes in active
tectonic regions

Numerous supporting research studies
were also carried out
In 2008, Next Generation Attenuation (NGA)
ground motion prediction equations (GMPEs)
were developed
USGS adopted the NGA-West1 GMPEs for the
US National Seismic Hazard Maps
NGA-West2 is a follow-up of NGA-West1

NGA-West2 Sub-Projects

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 ofdatabase was increased by a factor of 5.5

Moderate-to-large magnitude
worldwide database

Moderate-to-large magnitude
worldwide database

Examples of data added to NGAWest2 database
Earthquake Name*
Tottori, Japan
Niigata, Japan
Chuetsu-oki, Japan
Iwate, JapanEl Mayor-Cucapah, CA
Darfield, New Zealand
Christchurch, New ZealandWenchuan, China
L'Aquila, Italy*subset of added events

Year
2000
2004
2007
2008
2010
2010
2011
2008
2009

M
6.61
6.63
6.8
6.9
7.2
7
6.1
7.96.3

N Rec
414
530
616
367
238
114
10426348

Rrup Range (km)
1-333
8-300
10-300
5-280
11-2401-540
2-440
1-15005-230Comparison of NGA-West1 & NGA-West2
databases
Data
Set # EQs # Rec
Sa TypeDamping
NGAWest1 173 3,551 AR, GMRotI50
5%0.01 - 10

NGAWest2 610 19,400

0.01 - 20

AR, RotDnn
AR= As-recorded

0.5-30%Periods(sec)RotDnn definition
At each period, rotate horiz. components,

RotD50 = 50 percentile,

RotD100 = max,

RotD00 = min

Motivation: Users can use the maximum
rotated motionVs30 distribution
Measurements versus inferred values(estimated by various methods such asslop, geology,…)2008 Database

Courtesy: Jon Stewart

2012 DatabaseWhy did we add small magnitudedata?
Motivation:
 NGA-West1 models over-predicted motions

for small magnitude

 In the future, we can analyze multiple

events recorded at same site tocharacterize the site variability (singlestation Sigma)

 In the regions that have mainly small

magnitude data, they can compare NGA
with their data

Magnitude scaling at small magnitudePGASA(1.0s)

00

Acceleration (g)

1010

10-1
10-1

10-2
10-2
Rrup = 0 km
Rrup = 10 km
Rrup = 50 km
Rrup = 200 km

10-34.5

5.0

5.5

6.0

6.5

7.0

Moment Magnitude

7.5

8.0

10-3-4
8.5 10 4.5

5.0

5.5

6.0

6.5

7.0

Moment Magnitude

7.5

8.0

8.5

Public availability of the databaseOn May 15, 2013, the flatfiles forhorizontal components were posted at
PEER web site

http://peer.berkeley.edu/ngawest2/databases/

All metadataSpectral ordinates (RotD50) values at morethan 100 periods

Flatfile of the vertical ground motion will
be posted in September 2013

Public availability of the databaseActual timeseries (“timehistories”) will
be available fordownload in Fall2013
PEER web site
will be updated
to give morechoices to theusers to searchand download

Update NGA GMPEs for horizontal motionUsing the latest database, and

Using supporting research on:
HW/FW model using simulations data Update of nonlinear soil response

New classification of “main shock” vs“aftershocks”

 Directivity of ground motion…

NGA-West2 GMPE Developer Teams

Abrahamson-Silva-Kamai (ASK)

Boore-Stewart-Seyhan-Atkinson (BSSA)Campbell-Bozorgnia (CB)Chiou-Youngs (CY)Idriss (I)Comparison of NGA-West2 GMPEs:
Strike-Slip, Vs30=760m/s

Courtesy: Nick Gregor

Comparison of NGA-West2 GMPEs:
Reverse, HW, Dip=45, Vs30=760m/s

Courtesy: Nick Gregor

Specific example:
Campbell-Bozorgnia 2013 modelSpecific example:
Campbell-Bozorgnia 2013 model

Magnitude Saturation

Campbell-Bozorgnia 2013 model:
Magnitude scalingMagnitude Saturation

Campbell-Bozorgnia 2013 model:
Magnitude scaling

Reduceover-prediction
at smallmoderatemagnitude

Campbell-Bozorgnia 2013 model:
Hanging-wall effects

Campbell-Bozorgnia 2013 model:Standard deviation: Total

Campbell-Bozorgnia 2013 model:Standard deviation: Total, Small Mag

Regionalization of GMPE
We found up to about 80km the behavior ofdistance attenuation of ground motion isalmost universal
 Distance attenuation beyond 80km, can beregionalized. Different Anelastic
attenuation:
 Japan/Italy: Higher attenuation rate
 China: Lower attenuation rate Than the rest of the world

We found that soil amplification in Japanslightly different than California for
Vs30>200m/sec; and very different for
Vs30<200m/sec

USGS has reviewed and adopted NGA-West2
GMPEs for the next US National Hazard Maps

Develop GMPEs for vertical component

NGA-West1 models
predicted only
horizontal groundmotions

Recorded data haveshown that verticalground motion canbe large at the sites
close to active faults
Vertical GMPEs will
be available inSeptember 2013

Strike slip, Firm soil, M=7.52.0rseis= 3 km
V / H Ratio



1.5

rseis=10km

1.0

rseis=20km

2/3
0.5
0.0
0.01

0.1

1Period (sec)

Do not use 2/3 to scale
horizontal motion to getvertical10Damping scaling of response spectra
0Scale GMPEs for
damping other than5%:
0.5% to 30%

Damping scaling
model is final;
PEER report alreadypublished

Spectral Acceleration

M=7 R=10km

10010al.

110Damping scaling of response spectra
Damping Scaling Factors

We have amodel to scale
spectralordinates as afunction of Damping

Magnitude DistanceDuration was important, but took care of
the effects approximately throughmagnitude and distanceDirectivity



NGA-West1 models
did not explicitly
include directivity ofground motion
Five directivity
models have beendeveloped35

1992 Landers, CA, EQ

Forward directivity
region34.5

Lucerne Valley
136 cm/sec

LatitudeRupture
propagation

Wide-band andnarrow-band models

This effort willcontinue in 2013-14

Epicenter

Joshua Tree
43 cm/sec

34
Backward directivity
region-117-116.5Longitude-116

Directionality (Polarization)
NGA models are for“geometric mean”
horizontal
components

Develop max and min
rotated spectra, as afunction of mag,distance,…
Examine relationshipof max/min spectrawith RotD50(50 percentile)
spectraRef: Boore (2010)

Site Response

NGA-West1 site amplification factors areinconsistent with NEHRP site amplification
factors
Goal: To make NEHRP and NGA site
amplifications consistent

Propose changes in NEHRP factors

This is both scientific and consensusbuilding task

Final report will be available to the public inAugust 2013

Many people have been involved inNGA-West2

Technical Coordination Committee:External reviewers and oversightcommittee:

Abrahamson, Bozorgnia, Campbell

Chris Wills, Mark Petersen, John Anderson, Roger
Borcherdt, Silvia Mazzoni, Farzad Naeim

Funding agencies representatives:
Badie Rowshandel & Tom Shantz

People involved in NGA-West2 perTasks
Database: Ancheta, Darragh, Chiou, Silva,Stewart, Seyhan, Graves, Wooddell, Katke, Boore,Kishida, Al Atik, NGA developers
 GMPE Developers:Abrahamson & Silva

Campbell & Bozorgnia

Chiou & Youngs

Boore-Stewart-Seyhan-Atkinson



IdrissDamping: Rezaeian, Bozorgnia, Idriss,
Abrahamson, Campbell, Silva & GMPE developers

People involved in NGA-West2 perTasks (Cont’d)Vertical: GMPE developers
Directivity: Spudich, Chiou, Baker, Shahi,, Bayless, Watsono
rv

Putting together pieces of a complicated puzzle
througha coordinated multidisciplinary Team WorkNGA-East ProjectNGA- East
Goal: To develop next
generation Ground
Motion Prediction
Equations (GMPEs)
for Central & EasternUS
 Stable ContinentalRegions (SCRs)


Sponsors: NRC, EPRI,USGS, DOE

NGA-East: Selected Sub-Projects
Database:
Compile a database of recorded motions
from CEUS and other Stable ContinentalRegions (SCRs)
Geoetchnical Engineering:Linear and nonlinear site responses; reference
rock condition; reference “Kappa”; …

NGA-East: Selected Sub-Projects


Source-Site Path: Investigate
geometrical spreading steeper than 1/R;
Q; …
Ground Motion Simulation: Generatecalibrated & validated simulated GMs for
CEUS to be used by GMPE developers

NGA-East: Selected Sub-Projects


GMPE Development
 Next generation attenuation models forCEUS; applicable to magnitude 4-8,distances of 0-1000 km 5% damped response spectra at periods

0.01 to 10 sec

Project will be completed by May2015

NGA-Subduction

NGA-Sub: Phase I; Collection of Data fromTohoku and 2010 Chile EQs

In collaboration with Prof.
Midorikawa
For Tohoku EQ, PEER
already processed:More than 427
recordings for the mainshock
About 7 foreshocks(about 600 recordingstotal)

About 45 aftershocks
from M 6–7.7 (>3000
recordings total)
Courtesy: Yokota, et al (2011)

NGA-Sub: Phase II

Phase II: Collection
and processing of data
and metadata fromother subduction
earthquakes worldwide: Other Japan EQs,e.g., 2003 TokachiOki EQ, M 8.3
 Alaska, Chile, Mexico,Peru, Taiwan, CSZ, …
Collect and process
aftershock data
Develop new GMPE for
subduction

Reference: Tokachi-Oki EQ,
by Macias, Atkinson, andMotazedian (2008)

NGA-Sub: Phase III

Phase III (pendingfunding):
Carry out validated
simulations to fill the gap
in empirical data
Develop multiple GMPEs bymultiple developer teams(epistemic uncertainty)
Examine directivity
To be completed by May2016

GEM Global GMPEs Project

GEM: Global Earthquake Model An international non-profit organization

The PEER project goal is to select a set ofGMPEs for global PSHA, by using acollaborative approach To be used for global hazard and risk analyses

by GEM

PEER Team: 27 international experts fromaround the world
Schedule: On April, 30, 2013 seven final
reports were submitted to the GEM Foundation

On-Going & Future WorkNGA-Subduction and NGA-East are ongoing We are preparing proposal for NGA-West3

 Expanding the applicability of GMPEs for harderrock and softer soil
 Inclusion of “Kappa” in GMPEs
 Inclusion of topographic effects
 Inclusion of simulation (+ empirical data)
 …
PEER is very interested incollaborating with Japan, China, Korea
and Taiwan on all ground motion
hazard issues

THANK YOU!