SGMSv5-User-Manual-Draft

Engineering Seismology Laborator Laboratory y Memorandum

From: rom: Date: Subject:

B. Hall Halldo dors rsso son n and and A. S. Papag apageo eorg rgio iou u July 14, 2004 Region Region specific specific ground ground motio motion n simulati simulations ons using using the the specific specific barrier barrier model

TABLE OF CONTENTS SECTION

TITLE

PAGE

1

Parameters of the sto chastic mo dels

2

2

The SGMS co de

4

2.1

Input parameters

2.2 2.2

Usin Usingg SGMS SGMS to sim simulat ulatee sube subev vent ent time time hist histor orie iess from from the the Spec Specifi ificc Ba Barr rrie ierr Mo Mode del6 l6

A

SGMS vs. SGMP

4

9

A.1

Inter-plate regimes

10

A.2

Extensional regimes

11

A.3

Intra-plate regimes

12

B

C C.1

Rela Relati tiv ve loca locati tion onss of geol geolog ogic ical al faul faultts in Sout Southe hern rn Cali Califo forn rnia ia (fr (from USGS)

13

Updates

14

April 26, 2004

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EngSeisLab memo

Region specific ground motion simulations using the specific barrier model

1. Parameters of the stochastic models Table 1-1 summarizes the stochastic models and the corresponding model parameters that were used or obtained in the calibration of the specific barrier model for each of the three tectonic regimes (Halldorsson and Papageorgiou, 2004). In the case of intra-plate regime earthquakes (such as those of eastern North America), the recent calibration replace the previous ones (i.e., those of Halldorsson et al., 2002a,b). These models can be used for regional prediction of ground motion parameters or regional simulations of time histories using the stochastic method (see Halldorsson, 2004). The relevant software has been made available over the internet: http://civil.eng.buffalo.edu/EngSeisLab/. In this document we discuss shortly the codes developed for those purposes, and their use.

B. Halldorsson and A. S. Papageorgiou

July 14, 2004

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EngSeisLab memo


n e o it h t a n r o b il s a e c n e ile h t d i n i u g d f e e i n i r . a t B2 b . r o y e l t d e p a n v a it h C d c e e n p m se i u ss r n e a ,s v i e e g r me e i r w g e a t r st a e l h t ta u s sl l e r e p - e d a s o r t e mn t i h l a d n c i n o g a d o l ,l e o a sa n b m si o is s e i s n e r e c it t o ts s x i e a , h h e e c t o ts a l m it p e r n h t e it t o f n i o o s fo m r e t a d e t n u o ma d r a r o g a t t p l n e e e d d h t o n f me p o e y r e r i d a r n r ma o i mb g e u c r S fi f i o 1 - c e 1 p n it s o E a e L l B h t u Af m T o is

e t a l p a rt n I

0 8 1 , 0 6

5 5 . 0 , 1 7 . 0 , 2 , 8 . 2 , 8 . 3

0 =

κ

o p y h

R

m k 0 3 1 m m k k ≤ 0 0 r 3 7 1 < ≤ 0 > r 7 r

=

5 . 0

r

6 3 . 0

f0

8 6 = ) f(

)

r/ 0

r5 0 .0

-

s

T

Q

3 1 ( 0 0 r/ 7/ 7/ 1 1 1

-

+

5 .6 0 , 4 .5 0 , 6 3 . 0

 

e m i la g n e o R is ci n n e t o tc x E e T

e t a l p r e t n I

sr e t e m a r a P l e d o M

4 1 1 , 0 3

1 6 1 , 0 3

5 5 . 0 , 1 7 . 0 , 2 , 8 . 2 , 5 . 3

5 .5 0 , 1 .7 0 , 2 , 8 . 2 , 5 . 3

φ θ

L

σ

∆ , G

σ

∆

R ,

V , F , ρ , β


w

m k 0 3 ≤

M 9 5 0 .0 =

κ

5 2 .0 + 5 1 5 .0 =

d

ln

> r r

1

κ

d

n l

r e tl fi y c n e u q e rf h g i H

2

d

+ B 2J

R



=

r

) r0 3 (

−

r

f3

4 1 = ) f(

−

Q

s / m 0 4 9 = 0 3

¯V : k c o R

r a e n il n o N :l i o S

) 3 .6 − w

r5 0 .0

M ( 2 1 .0 − = ¯ η

+ s

T

3 6 . 0 , 2 5 . 0 , 5 .3 0



w

5 0 .0 =

4 .8 0

5 . 0

m k 0 3 ≤

M 9 5 2 .0 + 5 1 5 .0 =

m k 0 3

m k 0 3

> r r 5 . 0

−

1

−

r

) r0 3 (

8 8 . 0

f3

5 1 = ) f(

Q

s / m 0 6 7 = 0 3

¯V : k c o R

r a e in l n o N l:i o S

) 3 .6 − w

r5 0 .0

M ( 2 1 .0 − = ¯ η

+ s

T

3 6 . 0 , 5 5 . 0 , 1 3 . 0

 n o it a u n e t t a c i rt e m o e G

n o it a u n e tt a -

Q

n io t a c fi il p m a e ti S

T

, n o it a r u D

¯ η 2

0 1 =

ζ

) g o l l a r u t a n ( T

σ , σ , τ

. s e s a c ll a n i

β

5 7 . 0 e b o t d e m u s s a is y t i c o l e v e r u t p u R

July 14, 2004

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EngSeisLab memo


2. The SGMS code The Strong Ground Motion Simulation code, SGMS, uses the specific barrier model to describe the earthquake source in the stochastic modeling approach. Information on the stochastic modeling approach can be found in the draft report that we are preparing, and in the literature (e.g., Boore, 2003). The code is given as the source Fortran file SGMSv5.f90 and as the executable file SGMSv5.exe, compiled in the Windows 2000 operating system. The code also uses two other programs, respctra.f90 and respons.f90. The input file for the code is SGMSv5.inp and is described below. 2.1

Input parameters

The input file for the code is SGMPv5.inp and is structured in the following way: REGIME RMW R_JB IDV ISEED 1 6.5 10.00 3 8735285 ISPECTRA Tlow Thigh NT 0 .02 20.00 128 USER COMMENTS (min. 1 and max. 80 char.) This is a sample input file...

ISOIL 0

The input parameters in line 2 of the input file are •

REGIME – Specifies the tectonic region for which the simulations are made. When simulations are made for sites that are considered not to be in the “near-field”, the code uses the “far-field” expression for the seismic spectrum from the specific barrier model, invoked by assigning REGIME any of the following values – 1 – Inter-plate regimes (e.g., California, Turkey) – 2 – Regimes of active tectonic extension (e.g., the Basin and Range Province, USA; Greece) – 3 – Intra-plate regimes (e.g., eastern North America) When the sites are considered to be in the “near-field”, the “far-field” assumption does not apply and simulations from individual subevents of the specific barrier model must be carried out. In this case, REGIME should take the following values – 11 – Inter-plate regimes – 22 – Regimes of active tectonic extension – 33 – Intra-plate regimes

•

•

•

•

•

RMW – The moment magnitude of the main seismic event (also if subevent time histories are requested). R JB – The Joyner-Boore distance between the main event and station if REGIME is 1 or 2, and hypocentral distance if REGIME is 3. The hypocentral distance from the station to the subevent if REGIME is 11, 22 or 33. IDV – Specifies ground motion type (3-acceleration, 2-velocity, 1-displacement) to be simulated. ISEED – Seed number for the generation of realizations of a Gaussian white noise (integer, maximum length of 10 digits) ISOIL – Soil type specification parameter for accounting for the site response. The parameter isoil is ¯30 = 620 m/s) (BJ97) for regimes 1 and 2. = 1 – “Generic rock” ( V


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¯30 = 520 m/s) (BJ97) for regimes 1 and 2. = 2 – NEHRP class C (V ¯30 = 310 m/s) (BJ97) for regimes 1 and 2. = 3 – Generic soil ( V ¯30 = 255 m/s) (BJ97) for regimes 1 and 2. = 4 – NEHRP class D (V ¯30 = 2900 m/s) (BJ97) = 5 – Generic very hard rock in ENA ( V ¯30 = 760 m/s) (Fea96) = 6 – ENA NEHRP B-C boundary (V ¯30 = 940 m/s) = 7 – “stiff rock” in extensional regimes ( V = 10– Empirical nonlinear soil. Recommended description of sites in NEHRP D and lower NEHRP C (CD) for regimes 1 and 2. ¯30 = 700) for regimes 1 and = 12– Silva et al.’s (2000) NEHRP B-C boundary site amplification ( V 2. The input parameters in line 4 of the input file are – ISPECTRA - Takes the value 1 if the response spectra are to be output for the synthetic time histories (0 otherwise) – TLOW – The lowest natural period for which spectra are calculated (larger than 0.07 s) – THIGH – The highest natural period for which spectra are calculated (smaller than 20 s) – NT – Number of periods between TLOW and THIGH used in calculating the spectra The input parameters in line 6 of the input file are – USER COMMENTS – What is written here appears at the top of the output files (minimum 1 and maximum 80 characters). The ranges of M w (RMW) and distances (R JB) that were used in calibrating the model to data of each regime are given in Appendix A.


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FIGURE 2-1 The specific barrier model of Papageorgiou and Aki (1983a,b). The fault plane consists of an aggregate of circular cracks of radius ρ0 on a fault plane of length L and width W . The shaded area denotes barriers and the circles within each crack denote the rupture front at successive time instants.

2.2

Using SGMS to simulate subevent time histories from the Specific Barrier Model

When the site is considered to be in the “near-field” of the fault it becomes necessary to simulate time histories for each individual subevent of the specific barrier model, rather than the entire event (accregate of subevents). The SGMS code can be used for this purpose in which case the input parameters of SGMSv5.inp change as follows •

•

REGIME is now either 11, 22 or 33 depending on the regime. In all of the cases above, R JB is understood as the “hypocentral” distance from the site to the subevent.

Note that RMW is still the moment magnitude of the main event. With respect to calculating R JB, the user is responsible for the fault configuration i.e., the relative position of the fault (and subevents) with respect to the site(s). Parameters of the models that are helpful in this respect are listed below. Number of subevents The total number of subevents, N , that make up the specific barrier model is, according to our calibrations, 15, 6 and 4 for the inter-plate, extensional and intra-plate regime earthquakes, respectively. The areal extent of the N subevents All subevents of a specific event in a specific tectonic regime are assumed to have the same diameter 2 ρ , which is referred to as the “barrier interval” of the specific barrier model. The barrier interval is related to the moment magnitude M w of the main event through the following relationship ◦

log(2ρ ) = ◦

1.364 +

−

2 log∆σG 3

−

log∆σL + 0.5M w

(2-1)

where 2ρ is in km and ∆σG and ∆σL are in bars, given in Table 1-1. ◦


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Hypocenter For a given event and a station in the near-field, the user is responsible for the fault configeration i.e., arranging the subevents at a certain depth, and along the length and width of the fault. Considerable flexibility is given to the user in this case, as actual fault configurations vary greatly, and the configuration of the subevents in the specific barrier model is an idealization of the actual case. For simulating historical events, or events that are to take place on a known geological fault, the user may want to consider the actual or likely: direction of the fault along the length (fault strike, degrees from north, see e.g. Appendix B), slope of the fault plane from the horizontal ( fault dip, vertical faults have dip of δ = 90), and fault dimensions (length and width ), as a guide when arranging subevents on the fault. We provide an empirical relationship of “average source depth” with magnitude as a guide to assist the user in placing the hypocenter (rupture initiation location) at a depth: ln h = 0.515 + 0.259M w

(2-2)

(h in km) Generally however, the user is free to select the depth of the hypocenter, and its location on the fault plane. Knowing N and 2ρ (and h) allows the user to arrange the subevents on the fault plane in a similar manner as shown in Fig. 2-1. [We recommend that the lower edge of the fault plane be above 15 km in inter-plate and extensional regimes, above 30 km in intra-plate regimes; and that the upper edge be below 2 km.] ◦

∼

∼

∼

The subevent-site geometry then allows for an estimate of the hypocentral distance (input parameter R JB). The ratio of number of subevents along the length (N L ) and width (N W ) was during the calibration of the specific barrier model assumed to be approximately equal to 2. However, this ratio is left to the user’s discretion. For example, the user may consult empirical relationships of fault length and width from the literature (e.g., Wells and Coppersmith, 1994). The user controls the rupture sequence of the individual subevents. In this respect however, the specific barrier model assumes that the subevents rupture independently and randomly as the rupture front sweeps the fault plane starting at the hypocenter and traveling with rupture velocity V (taken as 0.75β (km/s) for all regimes). Realistic values of V are in the range 0.6 0.95 of β . −

The user can thus carry out simulations for each of the N subevents and sum the individual time histories at the site appropriately lagged in time depending on the source-receiver geomoetry. This produces a realization of the synthetic ground motion time history at the site from all subevents that make up the main event. “Near-field” seismic pulses are not simulated in the SGMS code and must therefore be added to the above final time history by the user, using the procedure outlined in Mavroeidis and Papageorgiou (2003).


July 14, 2004

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Boore, D. M. (2003). Simulation of ground motion using the stochastic method, Pure Appl. Geophys. 160, 635–676. Field, E. H., D. D. Jackson, and J. F. Dolan (1999). A mutually consistent seismic-hazard source model for southern California, Bull. Seism. Soc. Am. 89, 559–578. Halldorsson, B. (2004). The Specific Barrier Model: Its Calibration to Earthquakes of Different Tectonic Regions and the Synthesis of Strong Ground Motions for Earthquake Engineering Applications , Ph.D. thesis, University at Buffalo, State University of New York, Buffalo, New York. Halldorsson, B., G. Dong, and A. S. Papageorgiou (2002a). Calibration of the specific barrier model to eastern North America earthquakes, in 7 th U.S. National Conference on Earthquake Engineering (7NCEE), EERI. Halldorsson, B., G. Dong, and A. S. Papageorgiou (2002b). Earthquake motion input and its dissemination via the Internet, J. Earthq. Eng. and Eng. Vibration 1, 20–26. Halldorsson, B. and A. S. Papageorgiou (2004). Calibration of the specific barrier model to earthquakes of different tectonic regions, Manuscript in preparation for submission to the Bulletin of the Seismological Society of America. Mavroeidis, G. P. and A. S. Papageorgiou (2003). A mathematical representation of near-field ground motions, Bull. Seism. Soc. Am. 93, 1099–1131. Papageorgiou, A. S. and K. Aki (1983a). A specific barrier model for the quantitative description of inhomogeneous faulting and the prediction of strong ground motion. I. Description of the model, Bull. Seism. Soc. Am. 73, 693–722. Papageorgiou, A. S. and K. Aki (1983b). A specific barrier model for the quantitative description of inhomogeneous faulting and the prediction of strong ground motion. Part II. Applications of the model, Bull. Seism. Soc. Am. 73, 953–978. Silva, W., R. Darragh, N. Gregor, G. Martin, N. Abrahamson, and C. Kircher (2000). Reassessment of Site Coefficients and Near-Fault Factors for Building Code Provisions , Report to U.S. Geological Survey, National Earthquake Hazards Reduction Program. USGS Grant Award HQ-98-GR-01010. Wells, D. L. and K. J. Coppersmith (1994). New empirical relationships among magnitude, rupture length, rupture width, rupture area and surface displacement, Bull. Seism. Soc. Am. 84, 974–1002.


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A. SGMS vs. SGMP The calibration of the stochastic seismological model (using the specific barrier model to describe the earthquake source properties) was carried out taking advantage of random vibration theory in estimating spectral response. This chapter shows the agreement of peak ground acceleration (PGA) as predicted by the strong ground motion parameter (SGMP) code (through random vibration theory), and the strong ground motion simulations code (SGMS). In the figures in this chapter the lines are generated using SGMP, and the symbols are PGA values from synthetic acceleration time histories generated using the SGMS code. As the figures show, the two codes are fully consistent with one another.


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A.1


Inter-plate regimes

The stochastic model in SGMPv5 has been calibrated to pseudo-spectral velocity data from inter-plate earthquakes with the following properties: •

Moment magnitude range: M w 5.3–7.9

•

Joyner-Boore distance: RJB 0–155 km

•

Soil categories: Rock and soil

¯30 value, is known for a given site, the user may Note: If information on the NEHRP site class, or the V select the isoil parameter accordingly. For soil sites (NEHRP CD, D) however, we still recommend using isoil = 10 to account for nonlinear site response. The following figures show peak ground acceleration vs. distance as predicted by random vibration theory (SGMPv5, lines) and synthetic time histories (SGMSv5, symbols). Attenuation of Peak Ground Motion: Regime=1. Soil=01

3

10

2

2

10

2

Attenuation of Peak Ground Motion: Regime=1. Soil=10

3

10

10

]

2

s / m c [ A G P 1

]

s / m c [ A G P 1

10

10

M 5.5

M 5.5

M 6.5 M 7.5

M 6.5 M 7.5

0

0

10

10 0

10

1

2

10

10

Distance [km]

10

3

10

0

1

2

10

10

10

3

Distance [km]

FIGURE A-1 PGA vs. distance as predicted by SGMPv5 (lines) and SGMSv5 (symbols) for inter-plate earthquakes, for three different site conditions: 01–Generic Rock, and 10–Nonlinear Soil


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A.2


Extensional regimes

The stochastic model in SGMPv5 has been calibrated to pseudo-spectral velocity data from extensional regime earthquakes with the following properties: •


•

Joyner-Boore distance: RJB 0–100 km

•

Soil categories: Rock and soil

Note: The general rock class site condition in extensional regimes is that of “stiff rock”, for which the parameter isoil = 7. For the soil class site condition, either “generic soil” ( isoil = 3) or nonlinear soil (isoil = 10) amplification functions can be used. When simulating events that are large (e.g., > M w7) we recommend using the nonlinear soil amplification function. The following figures show peak ground acceleration vs. distance as predicted by random vibration theory (SGMPv5, lines) and synthetic time histories (SGMSv5, symbols). Attenuation of Peak Ground Motion: Regime=2. Soil=07

3

10

2

2

10

2


3

10

10

]

2

/s m c [ A G P 1

]

/s m c [ A G P 1

10

10

M 5.5 M 6.5 M 7.5

M 5.5 M 6.5 M 7.5

0

0

10

10 0

10

1

2

10

10

Distance [km]

10

3

10

0

1

2

10

10

10

3

Distance [km]

FIGURE A-2 PGA vs. distance as predicted by SGMPv5 (lines) and SGMSv5 (symbols) for inter-plate earthquakes, for three different site conditions: 07–“stiff rock” in extensional regimes, and 10–Nonlinear Soil


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A.3


Intra-plate regimes

The stochastic model in SGMPv5 has been calibrated to pseudo-spectral velocity data from intra-plate earthquakes with the following properties: •


•

Hypocentral distance: RJB 7–1000 km

•

Soil categories: Very hard rock in eastern North America

The following figures show peak ground acceleration vs. distance as predicted by random vibration theory (SGMPv5, lines) and synthetic time histories (SGMSv5, symbols). Attenuation of Peak Ground Motion: Regime=3. Soil=05

3

10

2

2

10

2


3

10

10

]

2

s / m 1 [c 10 A G P

]

s / m 1 [c 10 A G P

0

0

10

10

M 4.5 M 5.8 M 7.2

M 4.5 M 5.8 M 7.2

−1

−1

10

10 0

10

1

10

2

10

3

10

Distance [km]

4

10

0

10

1

2

10

10

3

10

4

10

Distance [km]

FIGURE A-3 PGA vs. distance as predicted by SGMPv5 (lines) and SGMSv5 (symbols) for inter-plate earthquakes, for two different site conditions: 05–Very hard rock in eastern North America (ENA) (κ = 0), 06–ENA NEHRP B-C boundary (κ = 0.010) Note: Use one of the following combinations of κ and isoil for the simulations: •

For “very hard rock in ENA”: Use either ( κ = 0, isoil = 0), or (κ = 0.006, isoil = 5).

•

For NEHRP B-C boundary site condition in ENA: Use (κ = 0.010, isoil = 6).


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B. Relative locations of geological faults in Southern California (from USGS) As an attachment to this document, we have prepared one called “Major Fault Systems in Southern California and their approximate locations.pdf”, based on the list of fault segments and groups that were considered by Field et al. (App. B 1999) for seismic hazard estimation for Southern California. We have obtained the geographical coordinates of the end points of the individual fault segments from the 2002 Revisions of the California seismic hazard and plotted their respective locations in Southern California, for convenience to the user.


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C. Updates C.1 •

•

April 26, 2004 Table 1-1 has been updated to reflect the more accurately determined model parameters. The following lists the incorporation of these parameters into the program files and gives an overview of what has changed. SGMSv5inp.txt – Added comments regarding R JB now being understood as hypocentral distance

when REGIME=3. •

SGMSv5.f90 – See header for short comments. The source lines that have been updated are tagged

as “!BH#1”. These are summarized below for REGIME=1: – Updated: ∆σL = 161 bar, Q(f ) = 153f 0.88 , Dgeo = 1/r for rx < 30 km, 1/(rx r)1/2 beyond that (igeo = 1). Updated the high-frequency source complexity factor: ζ = 0.12(M w 6.3) −

−

For REGIME=2: – Updated: ∆σL = 114 bar, Dgeo = 1/r for rx < 30 km, 1/(rx r)1/2 beyond that (igeo = 1). Updated the high-frequency source complexity factor: ζ = 0.12(M w 6.3). New site amplification function for “stiff rock” in extensional regimes (REGIME=2, ISOIL=7) has been added. −

−

For REGIME=3: – Updated: ∆σL = 180 bar. For this regime the distance measure is now understood as the hypocentral distance. The code has been recompiled and is given in the updated file SGMSv5.exe. •

•

Updated the files SGMPv5 INTER PGAtable.out and SGMPv5 EXTEN PGAtable.out according to the above updates for REGIME=1 and 2, respectively. SGMPv5inp.txt – Modified existing comments and added new ones regarding the updated

parameters and use of the code. •

SGMPv5.f – New site amplification function for “stiff rock” in extensional regimes (REGIME=2,

ISOIL=7) has been added. The code has been recompiled and is given in the updated file SGMPv5.exe. •

SGMPv5 INTER.inp, SGMPv5 EXTEN.inp, SGMPv5 INTRA.inp – New sample input files

for each regime are provided. They reflect the updated model parameters as discussed above. •

Appendices A.1, A.2 and A.3 in this document have been updated to reflect the above changes.

•

A new appendix was created regarding fault locations in Southern California.

•

The text in the document as a whole has been updated, and in some cases extended.


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SGMSv5-User-Manual-Draft

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