2013 EERI Annual Meeting Session: Tsunami Design

1. UW Tsunami Inundation Modeling:
Applications and Research
Relevant to Tsunami Design Issues
Frank González 1, Randy LeVeque 2, Loyce Adams 2
1 U. Washington, Earth Space Sciences, Seattle, WA
2 U. Washington, Applied Mathematics, Seattle, WA
14 February 2013
Session on Tsunami Design
2013 EERI Annual Meeting
Seattle, WA

2. Outline
!
• Applications in Support of Safe Haven Project
- Westport, WA: New Elementary School
- Long Beach, WA: Elementary School Berm
• GeoClaw: Advantages, Limitations, Ongoing Improvements
• Probabilistic Research and Development
- Crescent City, CA, Study
F. I. González

3. Tsunami Hazard Assessment of Ocosta School Site
Funded by Washington EMD!
Tsunami Hazard Assessment of the Ocosta School Site in Westport
Frank González, Randy LeVeque and Loyce Adams
WA Coast
Westport, WA
Ocosta School Site
University of Washington
Westport, WA, Google Earth image. Blue rectangle is area of fine resolution GeoC
tsunami model grid; white circle encompasses Ocosta School campus;
Study funded by Washington State Emergency Management Division
F. I. González

4. Proposed New Elementary School
!
Existing! Proposed! Local
!
Topography!
(wrt MHW)!
F. I. González

5. Near- and Far-field Scenarios
) and was also included in the Witter, et al. (2012) study of Bandon, OR. The Tsunami Pilot Study
“Maximum Considered Earthquakes” !
king Group (TPSWG, 2006) estimated the mean return period of this scenario to be about 750 years.
(b)
(a)
Westport
M9!
CSZ !
(c)
M9.1!
(d) AASZ !
6
Westport
F. I. González
re 1. (a) CSZ earthquake vertical displacement, in meters; note the coastal subsidence of 1-2 m at
port. (b) Westport coastline (black line) before CSZ event. (c) Westport coastline subsidence of 1-
Figure 1. (a) CSZ earthquake vertical displacement, in meters; note the coastal after subsidence.

6. Near- and Far-field Scenarios 0 m at Ocosta. 12 m Max Flood!
) and was also included in the Witter, et al. (2012) study of Bandon, OR. The Tsunami Pilot Study
“Maximum Considered Earthquakes” !
king Group (TPSWG, 2006) estimated the mean return period of this scenario to be about 750 years.
CSZ
(b) CSZ
(a)
Westport
M9!
CSZ !
(c)
0 m at Ocosta. 4.5tsunamiFlood depth for CSZ (
Figure 2. Maximum Max flooding
!
maximum depths at the top of the vertical color scales: 12.89 m
CSZ (18.7 ft) for the AASZ event. TheAASZ
spatial resolution of the com
CSZ Figure 2. Maximum tsunami flooding dep
The white lines are the coastline at MHW and the black arrow
AASZ
maximum depths
relatively low area of at the top of the vertical color loc
the ridge on which S. Forrest Street is sc
M9.1! (18.7scenario (left)AASZ event. co-seismic subsidence of a
CSZ ft) for the that results from The spatial resoluti
AASZ scenario (right).
(d) AASZ The white lines are the coastline at MHW and the
!
relatively low area of the ridge on which S. Forres
6
CSZ scenario (left) that results from co-seismic su
AASZ scenario (right).
Westport
F. I. González
re 1. (a) CSZ earthquake vertical displacement, in meters; note the coastal subsidence of 1-2 m at
Figure 2. Maximum tsunami flooding depth for CSZ (left) and AASZ (right) event. Note the
port. (b) Westport coastline (black line) before CSZ event. (c) Westport coastline subsidence of 1-
Figure 1. (a) CSZ earthquake vertical displacement, in meters; note the coastal after subsidence.

7. CSZ M9! AASZ 9.1
!
8-12 m/s
2-6m/s
Flow
Speed!
40 min
180 min
Arrival !
Times !
F. I. González

8. Tsunami Model
!
• GeoClaw (Geophysical Conservation Laws)!
- !Finite Volume, Nonlinear Shallow Water (NLSW) Eqs!
- !Extensive verification NTHMP validation/approval!
!
• Advantages!
- !Adaptive Mesh Refinement!
- !Open source, Well- documented!
!
• Limitations and Ongoing Research!
- !Need structures (short-term effort ?)!
- Need erosion, deposition!
- Need forces (H. Yeh, OSU; M. Motley, UW CEE)!
- !Need debris impacts (D. George, R. Iverson, USGS CVO)!
- !Need tests against 3D model to assess validity of NLSW
force estimates!
F. I. González

9. Long Beach, WA, Berm (Funded by WA EMD)!
!
0 250 500 750 1,000
Feet
F. I. González

10. Long Beach, WA, Berm (Funded by WA EMD)!
Previous Study by Venturato, et al., 2007.
!
!
Max$Currents$
(b)$
LB$Elem.$Schl.$Berm$in$blue$
(a)$
!
(c)$
2 m/s
0 250 500 750 1,000
Feet
F. I. González

11. Long Beach, WA, Berm (Funded by WA EMD)!
Previous Study by Venturato, et al., 2007.
!
!
Max$Currents$
(b)$
LB$Elem.$Schl.$Berm$in$blue$
(a)$
• Structures will
alter flow
forces!
• Debris will be
generated!
!
(c)$
2 m/s
0 250 500 750 1,000
Feet
F. I. González

12. the maximum depth of fluid at on-shore points that are inundated, and is the maximum 500 year Flood: ⇣-contours for p = 0.002
3.2 The
elevation above MHW for points o↵shore.
Each point in the region of a given color has an annual probability of 0.01 of inundation Figure 4 shows contours of ⇣ corresponding to p = 0.002. Each point in the region
Similarly,
above the corresponding ⇣ value. These are determined by examining the hazard of a given color has an annual probability of 0.002 of inundation above the corresponding ⇣
Probabilistic Study of Crescent City, CA
curve of
each point and determining what value ⇣ corresponds to p = 0.01. The outer limits of the outer limits of the area colored thus show the limits of the “500-year flood”.
value. The
(Funded by BakerAECOM for FEMA RiskMAP Program)
area colored thus show the limits of the “100-year flood”. !
“100-yr Tsunami”! “500-yr Tsunami”!
Table 1: Study Source Parameters. The slip values for AASZ06-08, KmSZe01-02, KrSZe01-03, and SChSZe01
are corrections to the values used in the Seaside study of Gonz´lez, et.al. [12]. The conditional probabilities
a
(weights) used in the analysis are 1 for the events with only one realization, and are given in the Total Weight
column of Table 3 for the CSZBe01r01-CSZBe01r15 realizations in Figure 16.
Source M Length Width Slip TM Fault Model Specification
Name (km) (km) (m) (yr)
AASZe01 9.2 1000 100 17.7 the Figure 4:
acsza9-18, in Table 1. This West) • 15 Far-Field Sources!
Figure 3: ⇣-contours for p=.01. This product was created using all 1313 study sourcesacszb9-18 (Model 1 ⇣-contours for p=.002. This product was created using all the study sources in Table 1. This
time 750 acsza19-28, a representative 15 Bandon study sources for CSZ with recurrence time TM = 332 years and a representative
includes the
the 15 Bandon study sources 9.2 CSZ1000 recurrence 17.7 TM = 332 years andacszb19-28 (Model 1 Mid)
includes AASZe02 for with 100
Japan source with recurrence time TM9.2 103 years. Note thatDist. the 750 depth onshore and the height 1 with recurrence time TM = 103 years. Note that ⇣ is the flow depth onshore and the height
Japan source
AASZe03
above MHW o↵shore, measured in meters.
AASZe04
=
9.2
600
1200
100
100
⇣ is flow acsza31-36, acszb31-36 (Model East)
• 15 Realizations of CSZ M9
above MHW o↵shore, measured in meters.
14.8 1133 acsza11-22, acszb11-22 (Model 2 West)
AASZe05
AASZe06
9.2
8.2
1200
300
100
100
14.8
1.9
750
875
acsza23-34, acszb23-34 (Model 2 East)
acsza28-30, acszb28-30 (Model 3 West)
Event !
AASZe07 8.2 300 100 1.9 661 acsza31-33, acszb31-33These maps are the “regulatory products” specified as the desired results of this proba-
(Model 3 Mid)
AASZe08 8.2 300 100 1.9 661 acsza34-36, acszb34-36 (Model 3 East) believe, however, that only looking at such maps may be misleading — the
bilistic study. We
KmSZe01 8.8 500 100 8.9 100 kisza1-5, kiszb1-5 inundated region can be very sensitive to the probability levels chosen for display, or to the
KmSZe02 8.8 500 100 8.9 100 parameters used in the modeling, such as the recurrence time of one event. In Section 9.2 we
kisza6-10, kiszb6-10
KrSZe01 8.5 300 100 5.3 500 kisza11-13, kiszb11-13 an example of this. We believe that it is possible to present the results of a probabilistic
show
KrSZe02 8.5 300 100 5.3 500 kisza14-16, kiszb14-16
study in ways to convey additional information, and o↵er some suggestions in Section 9.2.
KrSZe03 8.5 300 13 100 5.3 500 kisza17-19, kiszb17-19
SChSZe01 9.5 1100 100 45.3 300 sasza39-49, saszb39-49
14
TOHe01 9.0 500 200 Var. 103 Shao, et.al. [35]
CSZBe01r01-CSZBe01r15 Var. 1000 Var. Var. 332 Witter, et.al [40]
of these geophysical constraints on the slip distribution that is problematic, and this is
F. I. González
discussed in more detail, below. After much discussion with experts, we decided to use the
15 realizations of CSZ events developed for a recent study of Bandon, OR [40]. These are
discussed further in Section 7.6.2.

13. Probabilistic Study of Crescent City, CA
(Funded by BakerAECOM for FEMA RiskMAP Program)
!
• Advances in probabilistic methods!
- !Improved tidal uncertainty methodology!
- Improved stochastic realization methodology (in progress)!
• Largest uncertainty is earthquake source specification!
- Mean return periods, Tm , for each earthquake source!
- !Slip distribution (prevented use of new stochastic realization
methodology)!
F. I. González

14. Probabilistic Study of Crescent City, CA
(Funded by BakerAECOM for FEMA RiskMAP Program) !
• Issue: Standard regulatory product ( ζ – contour map ) is sensitive to Mean Return
Period, Tm – and could even be misleading. !
Sensitivity example for one CSZ source
Tm = 499 yrs
Tm = 501 yrs
ζ - contours
for p = .002
Figure 24: ⇣-contours for p=.002 when only one sample event is considered. Left: assuming recurrence=499
years. Right: assuming recurrence=501 years.
F. I. González

15. Probabilistic Study of Crescent City, CA
(Funded by BakerAECOM for FEMA RiskMAP Program) !
• Issue: Standard regulatory product ( ζ – contour map ) is sensitive to Mean Return
Period, Tm – and could even be misleading. But p – contour map is insensitive.!
Sensitivity example for one CSZ source
Tm = 499 yrs
Tm = 501 yrs
ζ - contours
for p = .002
Figure 24: ⇣-contours for p=.002 when only one sample event is considered. Left: assuming recurrence=499
years. Right: assuming recurrence=501 years.
Figure 24: ⇣-contours for p=.002 when only one sample event is considered. Left: assuming recurrence=499
years. Right: assuming recurrence=501 years.
p - contours
for ζ = 0.0
F. I. González
Figure 25: p-contours for ⇣ = 0 m, when only one sample event is considered. Left: assuming recurrence=499

16. Summary and Conclusions
!
• Deterministic “Maximum Considered Earthquake” Studies!
- !Useful for guiding tsunami design, and!
- !Need structures, erosion deposition, forces, debris impact!
• Probabilistic Hazard Assessment Studies!
- !Geophysical uncertainties main source of error!
- !Potentially more useful than deterministic studies, and!
- !Need structures, erosion deposition, forces, debris impact!
F. I. González

17. Thanks
!
F. I. González