of physicsbased ground motion earthquake simulations using a velocity model improved by tomographic inversion results 1 Ricardo Taborda 1 En Jui Lee 2 David Gill ID: 584669
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Slide1
Validation of physics-based ground motion earthquake simulations using a velocity model improved by tomographic inversion results
1
Ricardo Taborda
,
1
En-
Jui
Lee
,
2
David Gill
,
3
Po
Chen
,
4
Philip
Maechling
,
3
Thomas H.
Jordan
2,3
1
Center for Earthquake Research and Information, and Department of Civil Engineering, University of Memphis
2
Department of Earth Sciences, University of Southern California
3
Southern California Earthquake Center, University of Southern California
4
Department of Geology and Geophysics, University of WyomingSlide2
2
southern
California
models
CVM-H+GTL
CVM-S4.26
CVM-H
CVM-S
Alternative velocity models
for southern California
Magistrale
et al. (1996, 200)
Kohler et al. (2003)
(…) +
Chen et al. (2011)
Lee et al. (2011, 2013)Gil et al. (2013, 2014)
Süss and Shaw (2003)Süss et al. (2005)Plesch et al. (2007, 2009)
(…) +Ely et al. (2010)Slide3
3Crustal structurebasin depths at fixedvalues of
VsSlide4
4Basins geometrydepth to Vs = 1 km/s
CVM-S
CVM-HSlide5
5Taborda and Bielak (2014)BSSA, 104(4): in press
Recent work using different velocity models
case study: 2008 Chino Hills earthquake
Taborda and
Bielak
(2013)
BSSA, 103(1): 131–156Slide6
6
southern
California
models
CVM
-H+
GTL
CVM-S4.26
CVM-H
CVM-S
Alternative velocity models
for southern California
Magistrale
et al. (1996, 200)
Kohler et al. (2003)
(…) +Chen et al. (2011)Lee et al. (2011, 2013)
Gil et al. (2013, 2014)Slide7
7The latest CVM-S4.26 velocity modeltomographic inversion results and merge into CVM-S
CVM-S4.26
(Final Model)
CVM-S
(Base Model)
Magistrale
et al. (1996, 200)
Kohler et al. (2003)
Built as a model with
“arbitrary” resolution
(…) +
Chen et al. (2011)Lee et al. (2011, 2013)Starting model
discrete version of themodel with fixed resolution:regular grid every 500 mand minimum Vs
= 1000 m/s3D tomographic
inversion yieldsperturbations tostarting model
inversion processincluded 26 iterationsPo Chen and En-Jui Lee
Recovering and merging process
various scheme(s) devised to recover model featurestruncated by the startingmodel and merge the
pertur-bations
back into the model
for “arbitrary” querying
resolution
Distributed
via SCEC’s UCVM
(…) +
Gil et al. (2013, 2014)Slide8
8The CVM-S4.26 velocity modelmerging alternativesOption 1
Base
Vs
<
1 km/s
Use
Starting Props.
+ Perturbation
Negative
Perturbation
Final Model
NO
YES
Use
Base Props.
+ Perturbation
UseBase Props.
NO
YES
c
hecks whether base model
is softer than starting model
—inside a basin?—
if the base model is softer
checks whether the perturbation
will make it even softer
prevents the perturbation from
making softer than the base model
—preserves floor base props.—
otherwise it
hardens the
base model
otherwise it
hardens the
starting modelSlide9
9The CVM-S4.26 velocity modelmerging alternativesOption 2
Base Props.
< Starting
Use
Base Props.
Negative
Perturbation
Final Model
NO
YES
Starting Values
+
Perturbation
Use
Base Props.
NO
YES
Positive
Perturbation
YES
c
hecks whether base model
is softer than starting model
—inside a basin?—
if the base model is
softer, checks whether
the perturbation will
make it even softer
prevents the perturbation
from making softer than
the base model
prevents the perturbation
from making stiffer than
the base model
if the base model is
stiffer, checks whether
the perturbation will
make it even stifferSlide10
10The CVM-S4.26 velocity modelmerging alternativesOption 3
Base Props
.
<
Starting
Use
Starting Props.
+ Perturbation
Final Model
NO
YES
Use
Base Props.
c
hecks whether base model
is softer than starting model
—inside a basin?—the base model ispreserved everywhereit is softer than the
starting modelthe inversion results are
used everywhere elseSlide11
11
Comparison between base and merged models
CVM-S
CVM-S4.26 Option 1
CVM-S4.26 Option 2
CVM-S4.26 Option 3
Surface shear wave velocity (
Vs
) in m/sSlide12
12Largest earthquake in the L.A. region since the 1994 Northridge earthquake.Combination of thrust and strike-slip faulting between the Whittier and Chino faults.
No significant damages, no fatalities.
Excellent opportunity for testing assumptions and methodologies.
Recorded in over 450 strong motion station from different seismic networks. 336 surface stations within simulation domain.
The
2008 chino hills earthquake
and region of interestSlide13
13Low-frequency (0–0.5 Hz) ground motionselected locations
Data
Starting model
Inverted modelSlide14
14“High”-frequency (0–4 Hz) ground motionselected locations
Data
Base model
Merge Option 1
Merge Option 2
Merge Option 3Slide15
6 – 8Good
4 – 6
Fair
0 – 4
Poor
8 – 10
Excellent
15
» Anderson (2004)
13
th World Conf. Earthq. Eng.
» as modified inTaborda and Bielak (2013)Bull. Seismol. Soc. Am. 103(1):131–156
AriasIntensity
EnergyIntegral
Duration
PGA
PGV
PGD
Fourier
Spectrum
Response
Spectrum
Cross
Correlation
Validation criteria
goodness of fitSlide16
16
CVM-S
CVM-S4.26 Option 1
CVM-S4.26 Option 2
CVM-S4.26 Option 3
GOF scores
comparison
(0–0.25 Hz)Slide17
17
CVM-S4.26 Option 1
CVM-S4.26 Option 2
CVM-S4.26 Option 3
GOF scores improvement
with respect to the base model
(0–0.25 Hz)
Scale corresponds to change in the GOF
score with respect to the values obtained
forthe simulation using the base CVM-S modelSlide18
18CVM-S
CVM-S4.26 (Option 1)
GOF scores improvement
with respect to the base model (0–0.25 Hz)Slide19
19CVM-S
CVM-S4.26 (Option 1)
GOF scores improvement
with respect to the base model (0–0.25 Hz)Slide20
20Improvements beyond inversion fmaxwith respect to the base model (0–4 Hz)
CVM-S
CVM-S4.26 (Option 1)Slide21
21Improvements beyond inversion fmaxwith respect to the base model (0–4 Hz)
GOF score change
w.r.t
.
base model validationSlide22
22» general improvements in the synthetics are obtained but some areas will need further attention
» changes in GOF scores are of the order of 1 to 4 points maximum
»
additional improvements are unlike to come from marginal changes to the velocity models at this point, therefore other aspects (like frequency dependent attenuation and coherency
i
n the source model) will need to be considered
Closing remarks and future workSlide23
Validation of physics-based ground motion earthquake simulations using a velocity model improved by tomographic inversion results
23
Ricardo Taborda
,
1
En-
Jui
Lee,2 David Gill
,3 Po Chen
,4 Philip Maechling,3
Thomas H. Jordan2,3
1 Center for Earthquake Research and Information, and Department of Civil Engineering, University of Memphis2 Department of Earth Sciences, University of Southern California
3 Southern California Earthquake Center, University of Southern California4 Department of Geology and Geophysics, University of Wyoming