Sismovalp final meeting, Martigny, 02/10/2006 SISMOVALP WP6 Alpine ground motion Numerical benchmark of ground motion simulation in the Grenoble valley Description and first results
Sismovalp final meeting, Martigny, 02/10/2006
SISMOVALP WP6
Alpine ground motion
Numerical benchmark of ground motion simulation in the Grenoble
valleyDescription and first results
Sismovalp final meeting, Martigny, 02/10/2006
ESG2006 Numerical benchmark
Sismovalp final meeting, Martigny, 02/10/2006
Numerical Benchmark of 3D ground motion simulation in the Grenoble
Valley : Description and First Results
Emmanuel Chaljub, Seiji Tsuno, François Thouvenot, Michel Dietrich, Pierre-Yves
Bard
+ many colleagues & predictors
Sismovalp final meeting, Martigny, 02/10/2006
Overview• Introduction
• Background Data– Tectonic context / Seismicity (F. Thouvenot)– Geophysical and geotechnical data (M. Dietrich)
• General description and first results (E. Chaljub)– Description of the benchmark : model and events– Participation / Methods– Outline of the Grenoble basin seismic response
• Detailed comparisons (S. Tsuno)– Addressed topics and comparison methods– Example results– Preliminary Conclusions
• Recap / Lessons / Benchmark Future
Sismovalp final meeting, Martigny, 02/10/2006
Proposed predictions"Imposed"
• 2 weak motion events– W1, W2
• 2 strong motion events– S1, S2– Extension of W1, W2 to
stronger events– Source : imposed geometry
and kinematics
• + "Free-style"– M6 (S1) : Estimate +
uncertainties• (NL, source variabilities)
Sismovalp final meeting, Martigny, 02/10/2006
Material provided to participants : topographies
Surface : 50 m gridstepBedrock / sediment
interface: 250 m gridstep
Sismovalp final meeting, Martigny, 02/10/2006
Material provided to participants : velocity model
• Basin
– No shallow structure– Qs = 50
• Bedrock
– Vsurf= 3200 m/s– Qs = ∞
Stiff sediments but very hard bedrock : strong impedance contrast
Sismovalp final meeting, Martigny, 02/10/2006
Material provided to participants: source parameters
Sismovalp final meeting, Martigny, 02/10/2006
Material provided to participants : recordings
anchor deterministic calculations
empirical Green's functions
Borehole, at depth
Borehole, surface
Sismovalp final meeting, Martigny, 02/10/2006
Material NOT PROVIDED
• Input motion for 1D and 2D calculations
Sismovalp final meeting, Martigny, 02/10/2006
Results requested from participants : 1D case
• Time series (at least 30 s) of ground velocity at 1 station (borehole surface)
Sismovalp final meeting, Martigny, 02/10/2006
Results requested from participants : 2D methods
• Time series (at least 30 s) of ground velocity along a cross-section (10 stations, through borehole)
Sismovalp final meeting, Martigny, 02/10/2006
Results requested from participants : 3D case
• Time series (at least 30 s) of ground velocity for 40 stations)
• + PGV map
Sismovalp final meeting, Martigny, 02/10/2006
Results requested from participants : EMP methods
• Time series (at least 30 s) of ground velocity for 3 stations (including borehole)
Sismovalp final meeting, Martigny, 02/10/2006
Results received
Sismovalp final meeting, Martigny, 02/10/2006
Results received : details
1818
ParticipationParticipationParticipationParticipationContribution to Numerical benchmark
Frequency band analyzed
0.1 1 10 40
ID18ID09ID08ID17ID16ID15ID14ID10ID07ID13ID12ID11ID06ID05ID04ID03ID02ID01
1D
2D
EM
3D
Method S1 S2 W1 W2 FS NL Fmin (Hz) Fmax (Hz) No. time his.1D ○ ○ ○ 0.05 10 8
1D ○ ○ ○ 0.3 50 120
2D ○ ○ ○ 8 65
2D ○ ○ ○ ○ 8.5 77
2D ○ ○ ○ ○ 0.3 50 1200
2D ○ ○ 10 44
EM ○ ○ 0.8 40 72
EM ○ ○ 10 234
EM ○ 1 40 12
3F ○ ○ ○ ○ 1 480
3F ○ ○ ○ ○ 2 492
3F ○ ○ ○ ○ 0.5 480
3F ○ ○ ○ ○ 0.2 2 480
3F ○ ○ ○ ○ 0.48 480
3F ○ 2.5 120
3T ○ ○ 0.1 2 240
3T ○ 2.5 117
3T ○ ○ ○ ○ 2 492
Total = 5213
Frequency (Hz)
1919
Addressed topicsAddressed topicsAddressed topicsAddressed topics1. Overall variability (S1 case at Borehole site)1. Overall variability (S1 case at Borehole site)
Each method; 1D, 2D, 3D Flat, 3D Topo., EGF-> Waveform, Input motion-> Fourier spectra, Spectral ratio-> Non-linear (1D, 2D) & Topography effects (3T)
2. Comparison method2. Comparison method-> Waveform, Maximum values (PGV)-> Fourier spectra, Spectral ratio, Resonance peak
3. Applying misfit criteria to 3D estimations (S1 case)3. Applying misfit criteria to 3D estimations (S1 case)-> Anderson’s method-> Kristekova’s method
4. Additional learnings4. Additional learnings-> from S2-> from W1/W2, match with observation ?
2020
Overall raw variability Overall raw variability –– Time Time domaindomain
Overall raw variability Overall raw variability –– Time Time domaindomain
Velocity Waveform at bore-hole site (OGFB & OGFH)
Input (GL -541.5m) Surface (GL)
Time (sec)
Vel
ocity
(m
/s)
- E
W a
nd
SH
(1&
2D
)
OGFH (GL) 1D(Linear) 1D(NL) 2D(Linear) 2D(NL) EM 3F 3T
0 5 10 15 20 25 30
-2
0
2
Time (sec)
Vel
ocity
(m
/s)
- E
W a
nd
SH
(1&
2D
)
OGFB (GL -541.5m) 1D(Linear) 1D(NL) 2D(Linear) 2D(NL) EM 3F 3T
0 5 10 15 20 25 30
-2
0
2
1D
2D
EM
3F
3T
1D
2D
EM
3F
3T
2121
Comparison Comparison -- Spectra SpectraComparison Comparison -- Spectra Spectra
Fourier spectra at borehole site (OGFB & OGFH)
Frequency (Hz)Fou
rier sp
ectra
(Vel
.) EW and SH (1&2D)
3F 3T
1D 2D EM
OGFH (GL)
0.1 1 1050.50.001
0.01
0.1
1
10
Frequency (Hz)
Fou
rier sp
ectra
(Vel
.) EW and SH (1&2D)
3F 3T
1D 2D EM
OGFB (GL -541.5m)
0.1 1 1050.50.001
0.01
0.1
1
10
Two groups
2222
Comparison Comparison -- Spectral ratio Spectral ratioComparison Comparison -- Spectral ratio Spectral ratio
Spectral ratio at bore-hole site
Frequency (Hz)
Spe
ctra
l rat
io
SH
1D
0.1 1 1050.50.1
1
10
100
Frequency (Hz)
Spe
ctra
l rat
io
EW
EM
0.1 1 1050.50.1
1
10
100
Frequency (Hz)
Spe
ctra
l rat
io
EW
3F 3T
0.1 1 1050.50.1
1
10
100
1D 2D
EM3D
1D, 2D, EM, 3D and 3T
Frequency (Hz)
Spe
ctra
l rat
ioSH
2D
0.1 1 1050.50.1
1
10
100
Frequency (Hz)S
pect
ral r
atio
EW and SH (1&2D)
3F 3T
1D 2D EM
0.1 1 1050.50.1
1
10
100
2525
3D Flat3D Flat Simulation Simulation- case S1- case S13D Flat3D Flat Simulation Simulation- case S1- case S1
Bedrock depth of Grenoble basin
OGFH
OGFB
Time (sec)
Velo
city
(m/s
)
EW
ID15 ID16 ID17
ID07 ID10 ID14
OGFB(GL -541.5m)
0 5 10 15 20 25 30
-0.5
0
0.5
Time (sec)
Velo
city
(m/s
) EW
ID15 ID16 ID17
ID07 ID10 ID14
OGFH (GL)
0 5 10 15 20 25 30
-0.5
0
0.5
N
2626
Spectra - 3D Flat & case S1Spectra - 3D Flat & case S1Spectra - 3D Flat & case S1Spectra - 3D Flat & case S1
Frequency (Hz)
Fourier sp
ect
ra (V
el.) EW
ID15 ID16 ID17
ID07 ID10 ID14
0.1 1 20.50.001
0.01
0.1
1
10
Frequency (Hz)
Fourier sp
ect
ra (V
el.) NS
ID15 ID16 ID17
ID07 ID10 ID14
0.1 1 20.50.001
0.01
0.1
1
10
Frequency (Hz)
Fourier sp
ect
ra (V
el.) UD
ID15 ID16 ID17
ID07 ID10 ID14
0.1 1 20.50.001
0.01
0.1
1
10
Frequency (Hz)
Fourier sp
ect
ra (V
el.) EW
ID15 ID16 ID17
ID07 ID10 ID14
0.1 1 20.50.001
0.01
0.1
1
10
Frequency (Hz)
Fourier sp
ect
ra (V
el.) NS
ID15 ID16 ID17
ID07 ID10 ID14
0.1 1 20.50.001
0.01
0.1
1
10
Frequency (Hz)
Fourier sp
ect
ra (V
el.) UD
ID15 ID16 ID17
ID07 ID10 ID14
0.1 1 20.50.001
0.01
0.1
1
10
Fourier Spectra at OGFB (Gl -541.5m)
Fourier Spectra at OGFH (GL)
2727
Spectral ratio Spectral ratio -- 3D Flat & case S1 3D Flat & case S1Spectral ratio Spectral ratio -- 3D Flat & case S1 3D Flat & case S1
Frequency (Hz)
Spec
tral r
atio
EW
ID15 ID16 ID17
ID07 ID10 ID14
0.1 1 20.50.1
1
10
100
Spectral ratio at borehole site
Frequency (Hz)S
pec
tral r
atio
NS
ID15 ID16 ID17
ID07 ID10 ID14
0.1 1 20.50.1
1
10
100
2929Spectral ratio at borehole site
Spectral ratio Spectral ratio -- 3D Topo. & case S1 3D Topo. & case S1Spectral ratio Spectral ratio -- 3D Topo. & case S1 3D Topo. & case S1
Frequency (Hz)
Spec
tral r
atio
EW
ID08 ID09 ID18
0.1 1 20.50.1
1
10
100
Frequency (Hz)S
pec
tral r
atio
NS
ID08 ID09 ID18
0.1 1 20.50.1
1
10
100
Sismovalp final meeting, Martigny, 02/10/2006
Example results : PGV map
Sismovalp final meeting, Martigny, 02/10/2006
S1 case : 3D, Flat predictions
3232
ConclusionConclusionConclusionConclusion
Predicted waveforms and Fourier spectra exhibit a exhibit a large (too large, huge, unacceptable ?) variability.
Peak ground velocities on surface also exhibit a significant variability due to the differences in investigated frequency ranges.
BUT
Spectral ratios at bore-hole site are relatively stable, specially for the resonance frequency.
Differences in “Input motion” (i.e., source modelling) have the largest influence for the numerical simulations in this benchmark test.
Sismovalp final meeting, Martigny, 02/10/2006
Main learnings 1
• Difficulties of the exercise– Data and model format : to be standardized– HF / Short wavelength structure– Utility / absolute necessity of imposed exercises
• Simpler cases
– Consistency 1D / 2D / 3D : input motion• Simple for incident plane waves• ? Including source ?
– EGF : bad S/N ratio at low frequencies– Timing too tight
• Plan more time for predictions start earlier !– 2 years / 18 months / 9 months
Sismovalp final meeting, Martigny, 02/10/2006
Main learnings 2
• Outcomes– Large variability in input motion, significantly less
in site response– Consistency of 2D – 3D modelling (amplification
levels / frequency)– (Very) Encouraging results for different 3D models– Topography effects– Use of misfit criteria
• Definitely useful for objectively quantifying similarity / dissimilarity, but not yet enough practice
– Anderson's criteria more robust and engineering –oriented– Kristekova's : for already rather similar signals
• Need for looking at time histories, spectra, and spectral ratios
Sismovalp final meeting, Martigny, 02/10/2006
Example comparison after iteration (and bug correction)
Sismovalp final meeting, Martigny, 02/10/2006
Main learning
• 3D modelling is not yet "press-button"– Too fast applications may yield very wrong results
(and large untrust from end-users)
• BUT very similar results are possible event with completely different numerical schemes– (probably indicative of the "exact" solution)
• Conditions for careful use– well-validated techniques & codes– Well trained users– Careful model implementation– External review
Sismovalp final meeting, Martigny, 02/10/2006
Future of the Grenoble basin benchmark• Short term
– Summary report for Proceedings Volume 2• Not all results for all receivers• Focusing on some specific aspects
• Intermediate term– ? Second round for converging ?
• First results VERY ENCOURAGING ? Sismovalp extension ?– Other aspects
• Other receivers• Wavefield (array)• NL effects (2D)
– SPICE (2?)– ? Part of a collection of real sites for benchmarking
• Long term– Shallow structure and HF / BB response : deterministic or
stochastic ?
Sismovalp final meeting, Martigny, 02/10/2006
Acknowledgments
Sismovalp final meeting, Martigny, 02/10/2006
Acknowledgements
F. Anselmetti, C. Beck, C. Bordes, M. Campillo, E. Chapron, J. Converset,
C. Cornou, F. Cotton, M. De Batist, P. Finckh, E. Flavigny, P. Foray,
J.F Gamond, S. Garambois, J.R. Grasso, J.P Gratier, P. Guéguen, R. Guiguet,
S. Hatton, L. Jenatton, J. Jerram, S. Labanieh, B. Lebrun, F. Lemeille,
G. Menard, O. Méric, G. Nicoud, S. Roussel, P. Roux, L. Stehly,
S. Tadenuma, M. Vallon , P. Van Rensbergen,J. Verbeke, C. Voisin
Sismovalp final meeting, Martigny, 02/10/2006
ESG2006 Contributions relative to alpine valleys
• Predictions : Sxx
• Characteristics of Grenoble Valley
• Similar cases : Alpine Valleys
Sismovalp final meeting, Martigny, 02/10/2006
Prediction PostersS01 Numerical Simulation of Wave Propagation in the Grenoble Basin
H. Aochi, J. Rey and J. DouglasS02 1D and 2D linear and nonlinear site response in the Grenoble area
L.F. Bonilla, S. Nielsen and P.C. LiuS03 A ground-motion simulation approach coupling rock groundmotion prediction equations
and the empirical Green's functions methodM. Causse, F. Cotton and C. Cornou
S04 Spectral element modeling of 3D wave propagation in the alpine valley of Grenoble, France
E.Chaljub S05 Numerical Benchmark of 3D Ground Motion Simulation in the Valley of Grenoble, French
AlpsH. J. Chiang, T. M. Chang and K. L. Wen
S06 Site effects in a deep alpine valley for various seismic sourcesN. Delépine and J.-F. Semblat
S08 An Efficient Ader-Dg Method for 3-Dimensional Seismic Wave Propagation in Media With Complex Geometry
M. Käser, M. Dumbser and J. De La PuenteS09 Ground Motion Simulation of two Moderate Size Earthquakes in the Grenoble Area using
Summation of Small EarthquakesC. Kohrs-Sansorny, F. Courboulex and A. Deschamps
S10 Ground motion simulation on a 2D profile across the Grenoble basin using the Aki-Larner discrete wave-number method
C. Lacave and F. HollenderS12 Modeling of strong earthquake motion in the Grenoble Valley, French Alps
P.Moczo et al.S14 Kinematic composite souce model combined with EGF for modeling strong ground
motion Application to the Grenoble BasinJ. Ruiz, D. Baumont, P. Bernard and C. Berge- Thierry
S15 3D Ground Motion Simulation of the Grenoble valley by GeoELSEMarco Stupazzini
S30 Kinematic modeling of strong earthquake motion in the Grenoble Valley, French AlpsP. Franek and F. Gallovic
Sismovalp final meeting, Martigny, 02/10/2006
Grenoble ValleyS16 Seismicity of the Grenoble Area
F. Thouvenot, L. Jenatton and R. GuiguetS17 High-amplitude reflections in proglacial lacustrine basin fills of the NW
Alps : Origin and Paleoenvironment ImplicationsE. Chapron, M. Dietrich, C. Beck, P. Van Rensbergen, G. Menard, P. Finckh, G.
Nicoud, F. Lemeille, F. Anselmetti and M. De BatistS18 Seismic profiling and borehole measurements in the Isère valley near
Grenoble, France: 1 data acquisition and processingM .Dietrich, C. Cornou, G. Ménard, F. Lemeille, F. Guyoton and R. Guiguet
S19 Seismic profiling and borehole measurements in the Isère valley near Grenoble, France 2 InterpretationG. Ménard, M.Dietrich, M. Vallon , S. Tadenuma, C. Bordes, O. Méric and F.
Lemeille 126S23 Measurement and variability study of site effects in the 3D glacial
valley of Grenoble, French AlpsE. Chaljub, C. Cornou, J. Verbeke, J. Converset, C. Voisin, L. Stehly, J.R. Grasso, P.
Guéguen, S. Roussel, P. Roux, S. Hatton and M. CampilloS24 Characterising the non linearities of the lacustrine clays in the
Grenoble basinJ. Jerram, P. Foray, E. Flavigny and S. Labanieh
S25 Geotechnical, geophysical and seismological data used for the estimate of the highest amplified frequency in the basin of GrenobleP. Guéguen, S. Garambois, S. Tadenuma, B. Lebrun, and F. Cotton
Sismovalp final meeting, Martigny, 02/10/2006
Alpine Valleys
S26 Sites effects in the Vallorcine valleyC. Voisin, P. Guéguen, J.R. Grasso, C. Gomes
S27 Modelling of strong ground in the July 2004, Mw 5.2 Bovec earthquakeM. Vanini, M. Villani, E. Faccioli and A. Gosar
S28 Seismic Response Analysis of La Salle Fluvial Fan (Valle D' Aosta Italy)C. Turino, G. Ferretti, C. Eva, C. Gauzzi and R. Paolucci