Nobuyuki Takahashi (Hokkaido University) Ryoichi Onoda (Hokkaido University)
Multi-scale Simulation of tsunami from Tohoku Earthquake and Diffracted Tsunami Waves in Hokkaido
description
Transcript of Multi-scale Simulation of tsunami from Tohoku Earthquake and Diffracted Tsunami Waves in Hokkaido
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Multi-scale Simulation of tsunami from Tohoku
Earthquake and Diffracted
Tsunami Waves in Hokkaido
ZHU AIYU, Zhang DongningInstitute of Geophysics, China Earthquake AdministrationYuen Dave A.University of MinnisotaSong ShenyiComputer Network Information Center, China Academy of Science
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Outlines Governing equations and numerical
methods
Numerical simulation
Tsunami diffraction
Generation Propagation Runup Inundation
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Governing equations
2D nonlinear shallow water equations
Numerical methods Finite volume method (clawpack)
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Computing Domain longitude from 135° to 160°E latitude from 30 ° to 45°N DART 21401, DART 21413, DART 21418 and
DART 21419
http://www.ndbc.noaa.gov/dart.shtml
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Generation
length L=510km width W=150km the fault dips δ=14˚ rakes λ=81˚ strikes θ=193˚ average slip D=20m
Figure 1 The tsunami source model based on USGS
The first source model
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Figure 5 Offshore DART buoys wave height records versus computed results of the F1 model
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Figure 3 (a) Surface projection of the slip distribution superimposed on ETOPO2 (http://www.geol.ucsb.edu/faculty/ji/big_earthquakes/2011/03/0311_v3/Honshu.html); (b) The tsunami source model based on UCSB
The second source model
consists in a 190 sub-faults system
(a) (b)
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Figure 6 Offshore DART buoys wave height records versus computed results of the F2 model
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finite element method,
uses the GPS data for constrain condition
Figure 3 The tsunami source model of GPS
The third source model
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Figure 7 Offshore DART buoys wave height records versus computed results of the F3 model
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Which is the best source model ? The arrival times of the first wave, the results of F2
and F3 gives have a generally better agreement with the observed data, but not for case of F1 that is much slower than the observation.
The amplitude of the first wave, all of the model have there bad side and good side
It is indeed difficult to distinguish which one is the best
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correlation coefficient
Table 1 the correlation relation of the different models
ModelsBuoy gauge
Correlation coefficient
Average correlation strength
F1 21401 -0.7806 0.9226
21413 -0.9334
21418 0.9975
21419 0.9786
F2 21401 -0.8497 0.95602
21413 -0.9404
21418 0.9962
21419 0.9979
F3 21401 -0.4821 0.7902
21413 -0.6827
21418 1.0
21419 1.0
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The second source model is the best!
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Grid is 1800×3000PropagationVisualized by Avizo
Characters: (1) The tsunami wave is split into two waves, one is towards to the northeast coast of Japan, Another wave faces to the Pacific Ocean (2) tsunami wave is that first arriving wave is negative and then the positive wave which agrees with the observed data.
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Table 2 Maximum run-up values for calculated and observed values
LocationCoordinates(Lat,. Long.)
Computational height (m)
Observed height (m)
Shimakita (41.3636, 141.2306) 2.2838 2-3
Hachinohe* (40.5317,141.5278) 7.4699 2.7 or more
Miyako* (39.6436,141.9753) 15.6069 8.5 or more
Ofunato* (39.0194,141.7536) 20.4789 8.0 or more
Onahama (36.9369,140.8919) 3.9363 3.5- 4
Ohoshigyoko (35.7444,140.8583) 3.3574 3-4
Mera (34.9189,139.8247) 1.4855 1-2
Chiba (35.5681,140.0456) 0.5038 0-1
Okada (34.7894,139.3914) 0.5864 0-1
runup
http://www1.kaiho.mlit.go.jp/KANKYO/TIDE/real_time_tide/sel/index_e.htm the notation * means the maximum height of tsunami cannot be retrieved so far due to the troubles, and actual maximum height might be higher according to the observed data
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Adaptive mesh refinement method
Inundation
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Tohoku tsunami diffraction
movie
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Add the Gaussian noise to the topography
Topography
Topography add Gauss noise
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movies
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No flooding phenomenon at Hokkaido Island ?
Possible reason The earthquake source is not exactly correct The shallow water equations are not a perfe
ct model for the wave motion, The 1-mintute resolution etopo ocean bathy
metry is maybe not fine enough The Gaussian noise maybe not appropriate
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Thank you
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Diffraction