Preliminary report of numerical modeling based on the linear shallow water wave theory
 F. Imamura and S. Koshimura, DCRC, Tohoku Univ.
 
Acknowledgment : Bathymetry data was produced and provided by Dr.Ahmet- Yacliner, METU.


Information of initial tsunami, maximum water level and wave forms at 7 points along the coast

Governing equation
Numerical scheme
The linear shallow water wave theory
The Leap-Frog FDM
Length of the fault
Width of the fault
Depth of the fault origin
Dislocation
60 Km
20 Km
1 Km
6 m
Definition of each parameter is here.
 
Click in the table to watch the QuickTime movie of the simulation.
Model
Focal mechanism (Strike,Dip,Slip)
Origin of the fault plane
Initial surface displacement
Maximum water level
Tsunami wave forms at 7 points
hvd-case1
(268,84,180)
( 30.47 E, 40.72 N)
int_hvd1
max_hvd1
time_hvd1
hvd-case2
(268,84,180)
( 30.47 E, 40.78 N)
int_hvd2
max_hvd2
time_hvd2
usgs-case1
(91,76,179)
( 29.44 E, 40.72 N)
int_usgs1
max_usgs1
time_usgs1
usgs-case2
(91,76,179)
( 29.44 E, 40.76 N)
int_usgs2
max_usgs2
time_usgs2
usgs-case3
(91,76,179)
( 29.58 E, 40.76 N)
int_usgs3
max_usgs3
time_usgs3
usgs-case4
(91,76,179)
( 29.58 E, 40.67 N)
int_usgs4
max_usgs4
time_usgs4
Note : hvd is based on Harvard Univ. CMT solution and usgs is that of US Geological Survey
 

Comments and remarks on the computed results:
 
Model
Initial surface displacement
Maximum water level
Computed tsunami wave forms at 7 points
hvd-case1

Subsidence (negative) of -60cm due to the crustal movement is found along the southern coast of Izmit Bay, corresponding to the eyewitness

See int_hvd1

Maximum tsunami is +67 cm at the southern coast of Izmit bay

See max_hvd1

Negative initial motions of tsunami at Karamursel and Degirmerdere

See time_hvd1

hvd-case2

Subsidence in the north part of the bay and uplift in the south, not corresponding to the eyewitness

See int_hvd2

Computed tsunami becomes larger in the bay compared with hvd_case1. Maximum tsunami height is about +1 m in Degirmerder.

See max_hvd2

Positive initials are found in the southern part of the bay

See time_hvd2

usgs-case1

Subsidence in the north part of the bay and uplift mainly in the southern land of the bay mouth, not corresponding to the eyewitness

See int_usgs1

Tsunami is found only at the bay mouth.

See max_usgs1

Relatively large tsunami at Karamursel

See time_usgs1

usgs-case2

usgs-case 1 is shifted to the north. Uplift appears in the south.

See int_usgs2

Tsunami is found only at the bay mouth.

See max_usgs2

Positive wave comes first at Karamursel, because it is included in uplifted area.

See time_usgs2

usgs-case3

usgs-case 2 is shifted to the east. Uplift appears in the middle of the bay.

See int_usgs3

Tsunami is shifted a little to the inner bay.

See max_usgs3

Relatively large tsunami at Karamursel and Degirmerdere because of the location of the tsunami source.

See time_usgs3

usgs-case4

usgs-case 3 is shifted to the south. Only subsidence appears in the bay. Subsidence of -30cm is found along the southern coast.

See int_usgs4

Very small tsunami is found in the bay

See max_usgs4

Almost no tsunami except Karamursel.

See time_usgs4

 

Conclusions
 
  • The initial surface displacement computed by hvd_case1 model supports the subsidence of the southern coast of Izmit Bay. However, the computed tsunami height can not explain the damage in the coastal region reported by the University of Southern California Tsunami survey team.
  • The result of hvd-case 2/usgs-case3 is the best among 5 models to explain the magnitude of the damage in Karamursel, Degirmerdere and Golouk, although it still underestimates.
  • The effect of subsidence due to liquefaction and so on would be necessary.
 
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