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Hybrid modeling of the mega-tsunami runup in Lituya Bay after half a century

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The largest mega-tsunami dates back half a century to 10 July 1958, when almost unnoticed by the general public, an earthquake of M w 8.3 at the Fairweather Fault triggered a rockslide into Lituya Bay. The rockslide impact generated a giant tsunami at the head of Lituya Bay resulting in an unprecedented tsunami runup of 524 m on a spur ridge in direct prolongation of the slide axis. A forest trim line and erosion down to bedrock mark the largest runup in recorded history. While these observations have not been challenged directly, they have been largely ignored in hazard mitigation studies, because of the difficulties of even posing - much less solving - a well-defined physical problem for investigation. We study the mega-tsunami runup with a hybrid modeling approach applying physical and numerical models of slide processes of deformable bodies into a U-shaped trench similar to the geometry found at Lituya Bay.
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Hybrid modeling of the mega-tsunami runup in Lituya Bay after half
a century
Robert Weiss,
1
Hermann M. Fritz,
2
and Kai Wu¨nnemann
3
Received 20 February 2009; revised 1 April 2009; accepted 10 April 2009; published 9 May 2009.
[1] The largest mega-tsunami dates back half a century to
10 July 1958, when almost unnoticed by the general public,
an earthquake of M
w
8.3 at the Fairweather Fault triggered a
rockslide into Lituya Bay. The rockslide impact generated a
giant tsunami at the head of Lituya Bay resulting in an
unprecedented tsunami runup of 524 m on a spur ridge in
direct prolongation of the slide axis. A forest trim line and
erosion down to bedrock mark the largest runup in recorded
history. While these observations have not been challenged
directly, they have been largely ignored in hazard mitigation
studies, because of the difficulties of even posing much
less solving a well-defined physical problem for
investigation. We study the mega-tsunami runup with a
hybrid modeling approach applying physical and numerical
models of slide processes of deformable bodies into a
U-shaped trench similar to the geometry found at Lituya
Bay.
Citation: Weiss, R., H. M. Fritz, and K. Wu¨nnemann
(2009), Hybrid modeling of the mega-tsunami runup in Lituya Bay
after half a century, Geophys. Res. Lett., 36, L09602, doi:10.1029/
2009GL037814.
1. Geographical and Geological Setting
[2] Lituya Bay is a T-shaped tidal inlet cutting through
coastal lowlands and foothills of the Fairweather Range on
the Pacific south coast of Alaska (Figure 1). The bay fills
and slightly overflows a glacially carved depression with
characteristic submarine contours [Miller, 1960]. The pro-
nounced U-shaped trench with steep side walls and a broad
flat seafloor is 12 km long, up to 3.3 km wide and 220 m
deep. The Gilbert and Crillon inlets at the head of the bay
are part of a great trench that extends to the northwest and
southeast as a topographic expression of the Fairweather
transform fault.
[
3] Giant waves have likely occurred in Lituya Bay at
least five times in the past two centuries as a result of the
interplay between the geological and climatic setting [Miller,
1960]. Evidence of extreme wave-runup heights in 1853 or
1854, 1936 and 1958 have each been identified by sharp
trim lines of chopped trees to elevations above 100 m.
Two additional giant waves may have occurred in 1874
and 1899. These are not typical landslide waves as often
occur in other Alaskan fjords [Plafker, 1969; Synolakis
et al., 2002].
[
4] On 10 July 1958 beginning at 6:16 UTC intense
shaking from an M
w
8.3 earthquake [Tocher and Miller,
1959] caused 6.4 m horizontal and 1 m vertical tectonic
movement. An estimated rockslide volume of about 30
10
6
m
3
was released on the northeast wall of the Gilbert
Inlet up to an elevation of 915 m on a slope averaging
40 degrees (Figure 2). The slide material was composed of
amphibole and biotite schist. The initial slide geometry is
assumed to be a prism spanning 730 m to 915 m in width
and a thickness of 92 m normal to the slope. The lower
extent of the initial landslide position remains undefined.
The slide length was estimated to 970 m with a center of
gravity at 610 m elevation [Slingerland and Voight, 1979;
Miller, 1960]. The landslide sheared off and washed away
up to 400 m of ice from the Lituya Glacier front resulting in
a vertical ice wall perpendicular to Gilbert Inlet. The
landslide impact generated tsunami produced unprecedented
runup heights of 524 m on a headland in slide axis
prolongation and 208 m on the south shore of Lituya Bay.
The only other two landslide tsunami events known to
produce runup heights exceeding 200 m are Vajont reser-
voir in 1963 [Mu¨ller, 1964, 1968] and Spirit Lake in 1980
[Voight et al., 1981, 1983].
2. Experiments
[5] Based on generalized Froude similarity, Fritz et al.
[2001] built a 2D physical model of the Gilbert inlet scaled
at 1:675. The prototype unit volume of the slide was
determined to 37.2 10
3
m
3
/m based on a volume of
30.6 10
6
m
3
spread over an average width of 823 m. The
bathymetry and topography are simplified in the laboratory
by headlands with slope angles (a and b) of 45 degrees and
maximum uniform water depth (h) of 122 m at prototype
scale. The short tsunami propagation distance combined
with the confining wall formed by the Lituya Glacier may
justify a simplified two-dimensional approach given the
limited space for 3D spreading (Figure 2) [Fritz et al.,
2009].
[
6] The Lituya Bay rockslide w as modeled with an
artificial granular material (PP-BaSO
4
) matching the density
of the prototype schist. Given the unit volume, the slide
mass per unit width is m
0
= 98.5 10
3
t/m. The slide
granulate, initially contained in the slide box, is accelerated
by a pneumatic landslide generator to control landslide
dynamics and impact characteristics. Two laser-distance
sensors measure granular slide profiles before impact. A
laser-based digital PIV-system provides instantaneous
velocity vector fields in the slide impact and runup areas
providing insight into the kinematics of wave generation and
GEOPHYSICAL RESEARCH LETTERS, VOL. 36, L09602, doi:10.1029/2009GL037814, 2009
1
Department of Geology and Geophysics, Texas A&M University,
College Station, Texas, USA.
2
Civil and Environmental Engineering, Georgia Institute of Technology,
Savannah, Georgia, USA.
3
Museum fu¨r Naturkunde, Leibniz Institute, Humboldt University of
Berlin, Berlin, Germany.
Copyright 2009 by the American Geophysical Union.
0094-8276/09/2009GL037814
L09602 1of6
runup (Figure 3) [Fritz et al., 2003]. A capacitive wave gauge
is installed at a distance of 885 m from the slide impact along
with two runup gauges on the headland. In the physical
model, the slide mass is accelerated up to a prototype impact
velocity v of 110 m/s, which corresponds to an estimated free-
fall velocity with the centroid situated at 610 m elevation
[Law and Brebner, 1968; Noda, 1970], resulting in an impact
slide Froude number F = v/(gh)
0.5
= 3.18.
3. Hydrocode Modeling
[7] We adapted the multi-material hydrocode iSALE
(Impact Simplified Arbitrary Lagrangian Eulerian) [e.g.,
Wu¨nnemann et al., 2006, and references therein] to simulate
the Lituya Bay rockslide and tsunami. iSALE is a multi-
material, finite-difference hydrocode for simulating fluid
flows and deformations of solid bodies at subsonic and
supersonic speeds. A full description of the code is beyond
the scope of this paper and we refer to the manual of the
original code by Amsden et al. [1980] and more general
literature on hydrocode modeling, see, e.g., Pierazzo and
Collins [2004], Benson [1992] and Anderson [1987].
[
8] The basic approach of the algorithm used in iSALE is
to deform a regular grid of computational cells in a
Lagrangian step according to the velocity field computed
at the grid nodes. The deformed grid is then remapped (at
the end of each time step) onto the original orthogonal mesh
by advecting cell-based quantities (density, energy, momen-
tum) through cell boun daries. The overall method applied
then corresponds to an Eulerian solution scheme, where the
computational mesh is fixed in space and material flows
through it. To accurately simulate the movement of more than
one material in an Eulerian mesh, where material is fluxed
through a stationary mesh, requires the tracking of interfaces
between two materials within one cell (mixed cell). For
general information on interface tracking techn iques see,
e.g., Benson [2002].
[
9] The equations for conservation for mass, momentum,
and energy are solved by using a first-order upwind (full
donor cell) advection scheme. The material is treated
compressible, therefore an equation of state (EoS) is re-
quired to compute pressure as a function of density and
internal energy. Because compression is small (velocities
are much smaller than the speed of sound in the material),
we used, for simplicity, the Tillotson EoS [Tillotson, 1962]
for water, and granite for the slidebody and slope (for EoS
parameters see, e.g., Melosh [1989]).
[
10] To calculate the deviatoric stress tensor and its effect
on the velocity field, iSALE employs a deviatoric stress
model similar to that described by Collins et al. [2004] and
Ivanov et al. [1997]. In each time step, the second invariant
of the stress tensor in a cell is compared to the yield strength
of the material. Where the invariant exceeds the yield
envelope stresses are modified accordingly to meet the yield
strength of the material again.
[
11] The yield strength in the slide body is calculated by a
simple Drucker-Prager strength model with zero cohesion,
in which the yield strength Y is a linear function of pressure
Figure 1. Lituya Bay, Alaska satellite image (August 2001, Landsat) with superimposed 1958 landslide scar at the head of
the bay and forest trimline of tsunami runup after Miller [1960]. Note the forest destruction to a maximum runup elevation
of 524 m on a spur ridge and a maximum inundation distance of 1100 m from high-tide shoreline at Fish Lake.
L09602 WEISS ET AL.: THE 1958 LITUYA BAY TSUNAMI RUNUP MODELING L09602
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p: Y = C + mp (m is coefficient of internal friction and C =0
is cohesion). A Drucker-Prager material model appropri-
ately represents the behavior of granular material such as
gravel. For the rigid slopes and the basement we assumed an
infinite cohesion to avoid any movement or deformation
during the slide process. Water behaves like an inviscid
fluid in our model.
[
12] iSALE is validated against experimental studies of
hypervelocity impacts and other hydrocodes [Pierazzo et al.,
2008] and used successfully in modeling of meteorite impact
wave generation studies [Weiss et al., 2006; Wu¨nnemann
et al., 2007].
[
13] The general model setup is described in detail by,
e.g., Wu¨nnemann and Lange [2002]. iSALE supports two
different geometries: a Cartesian and a Cylindrical grid. For
two-dimensional computations, without radial spreading of
waves, the Cartesian coordinate system is used for the
modeling on prototype scale (Figure 2). Assuming a con-
stant volume of the slide body as in the laboratory experi-
ments, three parameters, (i) initial velocity, (ii) density, and
(iii) friction, constrain the wave generation. In order to match
the experimental data, an initial velocity is introduced to
meet the impact velocity of 110 m/s. The grains have a
density of r
g
= 2640 kg/m
3
, but the slide impact density is set
to the bulk density of the granular material, r
s
= 1610 kg/m
3
,
by introducing a porosity of 39%. iSALE supports treatment
of porosity as a function of volumetric strain [Wu¨nnemann
et al., 2006]; however, in our models we kept the porosity
constant at 39% during the slide process. Measured internal
friction coefficient of the granular material range between
0.91.0 [Fritz, 2002]. The friction coefficient of the slide
body in the model was set to m = 0.4 which corresponds to
the bed friction coefficient between the slope and the slide
body in the experiments. In the current version of iSALE it
is possible to use different internal friction coefficients for
the slope and the slide body, but the code does not allow for
specifying friction coefficients for interfaces between mate-
rials, e.g., slope and slide. For the dynamics of the slide
body it appears to be more important to match the bed
friction. Although the too small internal friction coefficient
of the slide body may enhance deformation of the body
during slide and impact into the water.
4. Results
[14] The time series of free surface elevations recorded by
the wave gauge documents the generation of a single impulse
wave which reaches its maximum 16 s after the impact at
152 m, propagating towards the headland (Figure 4). The
second crest after 48 s represents the wave reflection from
the head wall. Various empirical and theoretical predictive
relationships for the landslide-generated tsunami amplitude
Figure 2. Trimlines carved by tsunami in 1958: (a) NE_view of Lituya Bay from Cenotaph Island to Gilbert Inlet with
landslide scar at the head of the bay and trimlines of destructed forest with 524 m runup on spur ridge. (b) NW_view of
Gilbert Inlet with landslide scar, post_event Lituya Glacier front, forest destruction and soil erosion down to bedrock
(Photos: courtesy of USGS). (c) Gilbert Inlet illustration showing landslide dimensions, impact site and tsunami runup to
524 m on spur ridge directly opposite to landslide impact. Direction of view is north and the front of Lituya Glacier is set to
1958 post slide position. Illustration background is synthesized from two aerial photos recorded in 1997.
L09602 WEISS ET AL.: THE 1958 LITUYA BAY TSUNAMI RUNUP MODELING L09602
3of6
were compared with the Lituya Bay benchmark experiment
[Fritz et al., 2004]. The solutions by Hall and Watts [1953]
and Synolakis [1986, 1987] for solitary wave runup on
impermeable slopes match the experimentally measured
wave runup and the observed elevation of forest destruction
in Lituya Bay with predictions of R = 526 m and R = 493 m
based on experimentally measured incident wave parameters
H = 162 m and h = 122 m [Fritz et al., 2001]. This confirms
the 160 m wave height by Slingerland and Voight [1979]
inferred from back calculation from the runup. The wave
height of the measured solitary-like wave exceeds solitary
wave breaking criteria H/h = 0.83 [Tanaka, 1986]. Con-
sequently, the leading wave does collapse into a bore in
exp eriment s without the headland providing sufficient
propagation distance for wave evolution [Fritz et al.,
2003]. However the solitary-like wave in Gilbert Inlet
does not extensively break due to the short propagation
distance and the steep headland slope [Jensen et al.,
2003].
[
15] The slide body deforms in the numerical simulation
as it moves down the slope and is shown just before
impacting the water in Figure 4b (t = 4 s). The maximum
of the first peak in time series of Figure 4g corresponds to
Figure 4c (t = 19 s). Shortly after the maximum wave height
passes the tide gauge at 885 m from the headland of the
wave impact, partial breaking of the generated wave is
indicated in Fig ure 4d. The water mass runup on the
headland slope with subseq uent resurge creates the second
crest shown in Figure 4e (t = 53 s). Severe wave breaking
can be observed near the hillslope slope. In Figure 4f, the
second maximum passed and the water mass moved the
slide body moved to the west. Given the complexity of
the water movement and the nonlinearity of the generated
waves, time series of the water elevation help to evaluate
generated waves in laboratory experiments and in numer-
ical mo dels, but also serve as important validation for
numerical models. The agreement between experimental
and modeled data for the tide gauge in 885 m distance from
the impact slope is remarkable for both amplitude and
phase (Figure 4g). The maximum amplitude is A = 152 m
occurs approximately 16 s after the impact into the water.
The maximum runup of 518m mod eled with iSALE is
remarkably close to both observed and experimentally
measured runup heights of about 524 m.
5. Conclusion
[16] We studied the 1958 Lituya Bay rockslide and
tsunami numerically and by analog modeling in the labora-
tory, the latter at a scale of 1:675 using a unique pneumatic
landslide tsunami generator to control the slide impact
characteristics. To match the runup of 524 m, the slide
volume estimated by Miller [1960] was accelerated to an
impact velocity of 110m/s. The impact formed a large air
cavity and a highly nonlinear wave. Using the geometry of
the physical model at prototype scale, iSALE computed the
detailed evolution of the coupled free surface and slide
deformations. Comparisons between experimental and
modeling results show an excellent agreement, indicating
that all dominant processes are approximated adequately
raising the possibility of more advanced hazard mitigation
studies in the region. After half a century, the numerous
landslide deposits in Lituya Bay still remain to be mapped
to establish a baseline bathymetry prior to any possible
future landsl ide tsunami in Lituya Bay. With such a
bathymetry, the Lituya Bay rockslide and tsunami as well
as other extreme events can be understood with the help of
the same hybrid approach consisting of three-dimensional
Figure 3. Landslide tsunami experiment: (a) Experimen-
tal setup with pneumatic installation and measurement
systems: Laser distance sensors (LDS), capacitance wave
gages (CWG) and particle image velocimetry (PIV). (bd)
PIV velocity vector plot sequence of two synchronized
granular slide impact experiments with juxtaposed areas of
view and up_scaled parameters: Froude number F = 3.18,
impact velocity v = 110 m/s, mass per unit width m
0
=
95.5 103 t/m
0
, water depth h = 122 m, slope angles
a = b =45°, time increment 5.19 s with the first image at
t = 2.49 s after impact. Highlighted is the flow separation
on the back of the landslide and the formation of an
impact crater [Fritz et al., 2001].
L09602 WEISS ET AL.: THE 1958 LITUYA BAY TSUNAMI RUNUP MODELING L09602
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experiments [Fritz et al., 2009] and thre e-dimensional
modeling with iSALE-3D.
[
17] Acknowledgments. H.F. was supported by the National Science
Foundation under grant CMMI-0421090. Any opinions, findings, and
conclusions or recommendations expressed herein are those of the author(s)
and do not necessarily reflect the views of the National Science Founda-
tion. The two-dimensional experiments conducted at VAW (ETH Zurich)
were supported by the Swiss National Science Foundation under grant
2100-050586.97. K.W. was supported by DFG grant WU 355/5-2 and is
grateful for the financial support by the NOAA Center for Tsunami Research
(NCTR), PMEL. R.W. thanks management and personnel of the NOAA
Center for Tsunami Research and the Pacific Marine Environmental labora-
tory for their support and guidance during his tenure at NCTR.
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R. Weiss, Department of Geology and Geophysics, Texas A&M
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... The runup height is significantly determined by the wave height and the topography beyond the shoreline impacted by the wave. Only three cases of runup >200 m higher than the original water level are known (Weiss et al. 2009): (i) the 1958 Lituya Bay rockslide-debris flow (~30 million m 3 ) triggered a 'mega-tsunami' with a 524 m runup on the opposite side of this Alaskan fiord (Schwaiger and Higman 2007;Weiss et al. 2009;Franco et al. 2020); (ii) the 1980 multiple rotational landslide (~2.3 km 3 ) that initiated the eruption of Mount St Helens in Washington State caused an impulse wave in Spirit Lake with a runup of around 260 m (Voight et al. 1983); and (iii) the 1963 Vaiont rockslide. ...
... The runup height is significantly determined by the wave height and the topography beyond the shoreline impacted by the wave. Only three cases of runup >200 m higher than the original water level are known (Weiss et al. 2009): (i) the 1958 Lituya Bay rockslide-debris flow (~30 million m 3 ) triggered a 'mega-tsunami' with a 524 m runup on the opposite side of this Alaskan fiord (Schwaiger and Higman 2007;Weiss et al. 2009;Franco et al. 2020); (ii) the 1980 multiple rotational landslide (~2.3 km 3 ) that initiated the eruption of Mount St Helens in Washington State caused an impulse wave in Spirit Lake with a runup of around 260 m (Voight et al. 1983); and (iii) the 1963 Vaiont rockslide. ...
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Hazards in reservoirs and lakes arising from subaerial landslides causing impact waves (or ‘lake tsunamis’) are now well known, with several recent examples having been investigated in detail. The potential scale of such hazards was not widely known at the time of the Vaiont dam project in the 1950s and early 1960s, although a small wave triggered by a landslide at another new reservoir nearby in the Dolomites (northern Italy) drew the possible hazard to the attention of the Vaiont project’s managers. The Vaiont disaster in 1963 arose from a combination of disparate and seemingly unrelated factors and circumstances that led to an occurrence that could not have been imagined at that time. The ultimate cause was a very large landslide moving very rapidly into a reservoir and displacing the water. The resulting wave overtopped the dam to a height of around 175 m and around 2000 people were killed. This paper identifies and examines all of the issues surrounding the Vaiont dam and landslide in order to identify causal factors, contributory factors (including aggravating factors) and underlying factors. In doing so, it demonstrates that the disaster arose from the Vaiont dam project and cannot be attributed simply to the landslide. Underlying geological factors gave rise to the high speed of the landslide, which would have occurred anyway at some time. However, without the contributory factors that account for the presence of the reservoir, i.e. the choice of location for the project and management of the project with respect to a possible landslide hazard, there would have been no disaster. Indeed, the disaster could have been avoided if the reservoir could have been emptied pending further ground investigations. Understanding of this case provides many lessons for future dam projects in mountainous locations but also highlights an ongoing and perhaps under-appreciated risk from similar events involving other water bodies including geologically recent lakes formed behind natural landslide dams.
... In this section, the D-Claw results are compared to the experiment carried out by Fritz et al. (2001) Details on the Lituya Bay landslide tsunami can be found in the literature (Miller 1960;Weiss et al. 2009;Xenakis et al. 2017;Franco et al. 2020). ...
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Landslides are a severe geohazard around the world. When moving soil masses discharge into a large water body, a tsunami can be generated and exacerbate the devastating effects of the landslide as well as extend the affected area. In this study, based on on-site geological investigation and monitoring, a numerical depth-averaged, two-phase model is established for a hypothetical tsunami in the Suofengying reservoir induced by the potential Bianjiazhai landslide in China which has been previously identified as critical. The analysis of the simulation results shows that the maximum wave amplitude measured at gauge point closest to the landslide is 31 m, and the tsunami reaches the reservoir’s dam about 66 s after the landslide initiation. The inundation map provides potential risk areas that could be affected if a landslide occurs with the anticipated characteristics. Under similar conditions, the research results will help guide reservoir operation and landslide-tsunami disaster prevention. Simultaneously, examining the sequence of events in the tsunami disaster chain facilitates the analysis of the fundamental physics governing the propagation of tsunamis within reservoirs. This analysis contributes to the prediction and prevention of landslide-induced tsunami disasters occurring along reservoir banks.
... The total volume of the landslide is about 30 × 10 6 m 3 . It slides into the water at a speed of 110 m/s, resulting in an unprecedented water wave that reached 524 m up the local mountains (Weiss et al. 2009). The depth of water is 122 m, the width of water surface is 1342 m, and the slope angles of the sliding surface and the climbing surface are both 45°, as shown in Fig. 5. ...
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Landslide-induced waves often result in severe casualties, economic losses, and even catastrophic consequences, which are far more destructive than the landslide itself. In this paper, accurate geomorphological and geological characteristics of the Wangjiashan landslide in Baihetan Reservoir, southwest China, were obtained through field investigations, and a three-dimensional model was built for numerical calculation. Through the time series curve of cumulative deformation, the water level variation of the reservoir was found to be the major factor causing the landslide deformation and eventual failure. The generation and propagation progress of water waves induced by the Wangjiashan landslide was simulated by coupling the granular flow model and renormalization group turbulence model in FLOW3D. The results show that a large sliding mass silts up the channel, forming a landslide dam with a maximum height of 21.5 m. Nevertheless, it does not block the channel and will not affect standard navigation on account of the wide channel in this area. The maximum run-up wave height of waves spreading to the Xiangbiling resettlement area on the opposite bank is 3.7 m. As the resettlement area is only 1.3 km away from the landslide, and its elevation is only 2.5 m higher than the normal water level of the reservoir, landslide-induced waves should be considered a potential threat. The most vulnerable area affected by landslide-induced waves is about 8 km long along the river, where wave run-up heights are more than 1 m. The results in this paper have important reference values for the early warning and prevention of potential disasters caused by landslides and landslide-induced waves.
... In contrast, landslide induced tsunami possesses significant threat as it hits without any prior signal. The interest in the study of landslide induced tsunami accelerated in the research community after some disastrous occurrences in the mid twentieth century (Grand Banks, Newfoundland, Canada, 1929; Lituya Bay, Alaska, 1958; Malpasset Dam, France, 1959; Vajont dam, Italy, 1963; Papua New Guinea, 1998) [14][15][16]. On October 9, 1963, a massive landslide (larger than the reservoir volume) on the Vajont reservoir in Italy resulted a huge impulsive wave that propagated throughout the basin and overtopped the dam, resulting in massive flooding and destruction of several villages and towns downstream with approximately 2000 fatalities. ...
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... The 1958 Lituya Bay, Alaska (USA) landslide is one of the most spectacular examples of a subaerial landslide that caused large localized waves. It was set off from the great strike-slip earthquake in south eastern Alaska on 10 July 1958 [5][6][7][8][9] . The landslide, which fell into a narrow fjord, caused a slosh wave which reached about 520 m height, then continued out the fjord where it was at about 10 m' height when it first met the ocean and decreased quickly as it spread out in the open ocean [3] . ...
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We proposed new prediction models based on multilayer perceptron (MLP) which successfully predict the maximum run-up of landslide-generated tsunami waves and assess the role of parameters affecting it. The input is approximately 55,000 rows of data generated through an analytical solution employing slide’s cross section, initial submergence, vertical thickness, horizontal length, beach slope angle and the maximum run-up itself, along with its occurrence time. The parameters are first ranked through a feature selection algorithm and six models are constructed for a 9,000-row randomly sampled dataset. These MLP-based models led predictions with a minimum Mean Absolute Percentage Error of 1.1% and revealed that vertical slide thickness has the largest impact on the maximum tsunami run-up, whereas beach slope angle has minimal effect. Comparison with existing literature showed the reliability and applicability of the offered models. The methodology introduced here can be suggested as fast and flexible method for prediction of landslide-induced tsunami run-up.
... Miller (1960) reports of an extraordinary rockslide-induced wave in Lituya Bay (Alaska) in 1958, later analysed by e.g. Fritz et al. (2009) and Weiss et al. (2009). This wave had a run-up height of about 530 m and caused five victims. ...
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Chapter
In this chapter, the hybrid method of DEM-SHP is elaborated meant to solve the problem of “fluid–structure interaction (FSI)”, with special interest being directed to the landslide and its induced surge waves (tsunamis). The landslide body is discretized by distinct elements whereas the water body is simulated by smoothed particles. On the contact surface between the landslide body and water body, a handshaking algorithm via the interaction forces including repulsion, drag and buoyant are implemented. At the end of this chapter, a series of validations and application are disclosed.
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Landslides falling into water bodies can generate impulsive waves. The process of wave generation induced by far subaerial granular landslide has been investigated through series physical experiments. The slide Froude number has been quantified considered the parameters of slide mass and water such as grain size, water depth and impact angle. The effect of impact angle, grain size and water depth on the variation of generated wave amplitude is 0.11%, 1.52% and 2.89% respectively when every 1% change in the value of the parameter. On the three governing parameters the water depth is the most sensitive to the wave amplitude, secondly the grain size and final for the impact angle. The intruding pattern of granular debris, the landslide generated wave types and maximum wave amplitude have been systematically discussed. The degree of impact interaction between the slides and water under different conditions is characterized by the value of the slide Froude number, and the empirical relationships linking the slide Froude number with the produced wave amplitude and wave classifications have been conducted based on experimental data, which is useful to illustrate the triggering mechanisms and dynamic process of impact landslide waves on high debris avalanches.
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Subaerial landslides and volcano flank collapses can generate tsunamis with devastating consequences. The lack of comprehensive models incorporating both the landslide and the wave mechanics represents a gap in providing consistent predictions of real events. Here, we present a novel three-dimensional granular landslide and tsunami model and apply it to the 2014 Lake Askja landslide tsunami. For the first time, we consistently simulate small-scale laboratory experiments as well as full scale catastrophic events with the same model. The model captures the complete event chain from the landslide dynamics to the wave generation and inundation. Unique and complete field data, along with the limited geographic extent of Lake Askja enabled a rigorous validation. The model gives deep insights into the physical landslide processes and improves our understanding and prediction capabilities of frequent and catastrophic landslide tsunamis.
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Large water waves generated by landslides impacting with a body of water are known from Disenchantment and Lituya Bays, Alaska; Vaiont reservoir, Italy; Yanahuin Lake, Peru; Shimabara Bay, Japan; and many fiords in Norway. The combined death toll from these events most likely exceeds 20,000 people. Such waves may be oscillatory, solitary, or bores and nonlinear mathematical theories or linearizing assumptions are thus needed to describe their wave amplitudes, celerities, and periods. In this paper the following approaches are compared: (1) the Noda simulation of a vertically falling and horizontally moving slide by linearized impulsive wave theory and estimation of nonlinear wave properties; (2) the Raney and Butler modification of vertically averaged nonlinear wave equations written for two horizontal dimensions to include three landslide forcing functions, solved numerically over a grid for wave amplitude and celerity; (3) the empirical equations of Kamphuis and Bowering, based on dimensional analysis and two-dimensional experimental data; and (4) an empirical equation developed in this report from three-dimensional experimental data, i.e., log(ηmax/d) = a + b log(KE), where a, b = coefficients, ηmax = predicted wave amplitude, d = water depth, and KE = dimensionless slide kinetic energy. Beyond the slide area changes in waveform depend upon energy losses, water depth and basin geometry and include wave height decrease, refraction, diffraction, reflection, and shoaling. Three-dimensional mathematical and experimental models show wave height decrease to be a simple inverse function of distance if the remaining waveform modifiers are not too severe. Only the Raney and Butler model considers refraction and reflection. Run-up from waves breaking on a shore can be conservatively estimated by the Hall and Watts formula and is a function of initial wave amplitude, water depth, and shore slope. Predicted run-ups are higher than experimental run-ups from three-dimensional models. The 1958 Lituya Bay and 1905 Disenchantment Bay, Alaska events are examined in detail, and wave data are developed from field observations. These data and data based on a Waterways Experiment Station model are compared to wave hindcasts based on various predictive approaches, which yield a large range of predicted wave heights. The most difficult problems are in matching the exact basin geometry and estimating slide dimensions, time history, and mode of emplacement. Nevertheless, the hindcasts show that the mathematical and experimental model approaches do provide useful information upon which to base engineering decisions. In this regard the empirical equation developed in this report is at least as satisfactory as existing methods, and has the advantage of requiring less complicated input data.
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In the evening of November 3, 1994, a series of submarine landslides and associated waves destroyed the Pacific Arctic Railway Company (PARN) dock at Skagway, Alaska, killing one construction worker. Numerous geologic and hydrodynamic studies followed, in an effort to prove or disprove that construction failure was responsible for initiating the slide. We model the slide using two inundation models, the model known as TUNAMI-N2 (not TSUNAMI) developed at Tohoku University and the model VTCS-3 developed at the University of Southern California and now in use by NOAA and known as MOST. Both models when run under the same initial conditions and bathymetry provided consistent results about the hydrodynamic motions close to the PARN dock. The results qualitatively fit the eyewitness observations, using a combination of three slides, and suggest that the sliding started offshore along the fjord wall off the southern end of the dock and undermined the southern two thirds of the dock.
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