Motivated by the catastrophe in Babi Island, Indonesia (Yeh et al., 1994), during the 1992 Flores Island tsunami,
large-scale laboratory experiments were performed at Coastal
Engineering Research Center, Vicksburg, Mississippi, in a 30 m-wide,
25 m-long, and 60 cm-deep wave basin (Fig. 1).
Waves were realistically created in the tank by a horizontal wave
generator with 60 different paddles each 46 cm-wide and moving
independently. These experiments provided runup observations for
validating numerical models and supplemented comparisons with
analytical results (Kânoglu and Synolakis, 1998).
Figure 1: View of conical island (top) and basin (bottom).
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The detailed experiments are described elsewhere in greater
detail (Liu et al., 1995; Briggs et al., 1995; Kânoglu, 1998; Kânoglu and Synolakis, 1998). Briefly, a
Directional Spectral Wave Generator (DSWG), located at = 12.96 m from the island, generated waves with an
initial solitary wave-like profile. The 27.42 m-long DSWG consists
of sixty 46 cm-wide and 76 cm-high individual paddles, each of which
can be driven independently. This allowed performance of experiments
with different wave crest lengths. However, the cases presented here
were performed using all the paddles. Experimental results for
different wave crest lengths are given in Briggs et al. (1995) and Kânoglu (1998).
In the physical model, a 62.5 cm-high, 7.2 m toe-diameter, and 2.2 m
crest-diameter circular island with a 1:4 slope was located in the
basin (Fig. 2). Experiments were conducted at two
different water depths, 32 cm and 42 cm, but presented here with
dimensionless solitary wave heights
equal to 0.045, 0.091, and 0.181 at 32 cm. Each experiment was
repeated at least twice and maximum runup heights around the
perimeter of the island were measured at 24 locations. Wavemaker
signals were presented in Fig. 4 for
these cases to allow direct implementation of these solitary waves
as a wavemaker motion in the numerical models. Water-surface time
histories were
measured with 27 wave gages located around the perimeter of the island (Fig. 3). However, here, time histories of the surface
elevation around the circular island are given at four locations,
i.e., in the front of the island at the toe and gages closest to the
shoreline with
the numbers 9, 16, and 22 located at the , , and
radial lines, respectively
(Figs. 5-7.
Maximum runup measurements are given in
Fig. 8.
Figure 2: Definition sketch for conical island. All dimensions are in
cm. Not to scale.
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Figure 3: Schematic showing gage locations around the conical island.
Not to scale.
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Figure: Wavemaker motions for the generation of
, 0.091, and 0.181 solitary waves.
Target wave heights are given in the insets.
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Figure: Laboratory data for the time histories of surface elevation
for a
solitary wave at four gages and
cm. Gage 6 is located at the toe of the conical
island on 0 radial line. Gages 9, 16, and 22 are the gages
closest to the shoreline on the , , and radial lines, respectively. Initial wave is defined
half-wavelength (L/2, i.e., gages 1 to 4) away from the toe of the
conical island.
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Figure: Laboratory data for the time histories of surface elevation
for a
solitary wave at four gages and
cm. Gage 6 is located at the toe of the conical
island on 0 radial line. Gages 9, 16, and 22 are the gages
closest to the shoreline on the , , and radial lines, respectively. Initial wave is defined
half-wavelength (L/2, i.e., gages 1 to 4) away from the toe of the
conical island.
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Figure: Laboratory data for the time histories of surface elevation
for a
solitary wave at four gages and
cm. Gage 6 is located at the toe of the conical
island on radial line. Gages 9, 16, and 22 are the gages
closest to the shoreline on the , , and radial lines, respectively. Initial wave is defined
half-wavelength (L/2, i.e., gages 1 to 4) away from the toe of the
conical island.
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Figure: Maximum runup heights from the laboratory data for three
solitary waves
, 0.091, and 0.181 and
cm. Initial waves are defined half-wavelength
(L/2, i.e., gages 1 to 4) away from the toe of the conical
island.
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These experiments were used as benchmark tests for validating 2+1
numerical codes in the 1995 Friday Harbor, Seattle, Washington
Long-Wave Runup Models Workshop (Yeh et al., 1996).
References:
Briggs, M.J., C.E. Synolakis, G.S. Harkins, and D. Green (1995):
Laboratory experiments of tsunami runup on a circular island. Pure Appl. Geophys., 144, 569-593.
Kânoglu, U. (1998): The runup of long waves around piecewise
linear bathymetries. Ph.D. Thesis, University of Southern
California, Los Angeles, California, 90089-2531, 273 pp.
Kânoglu, U., and C.E. Synolakis (1998): Long wave runup on
piecewise linear topographies. J. Fluid Mech., 374, 1-28.
Liu, P.L.-F., Y.-S. Cho, M.J. Briggs, U. Kânoglu, and C.E.
Synolakis (1995): Runup of solitary waves on a circular island. J. Fluid Mech., 320, 259-285.
Yeh, H., P.L.-F. Liu, and C.E. Synolakis (1996): Long-Wave
Runup Models. World Scientific, 403 pp.
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