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Journal ArticleDOI

Near Field Characteristics of Landslide Generated Impulse Waves

15 Oct 2004-Journal of Waterway Port Coastal and Ocean Engineering-asce (American Society of Civil Engineers)-Vol. 130, Iss: 6, pp 287-302
TL;DR: In this article, landslide generated impulse waves were investigated in a two-dimensional physical laboratory model based on the generalized Froude similarity, and four wave types were determined: weakly nonlinear oscillatory wave, nonlinear transition wave, solitary-like wave and dissipative transient bore.
Abstract: Landslide generated impulse waves were investigated in a two-dimensional physical laboratory model based on the generalized Froude similarity. The recorded wave profiles were extremely unsteady and nonlinear. Four wave types were determined: weakly nonlinear oscillatory wave, non-linear transition wave, solitary-like wave and dissipative transient bore. Most of the generated impulse waves were located in the intermediate water depth wave regime. Nevertheless the propagation velocity of the leading wave crest closely followed the theoretical approximations for a solitary wave. Between 4 and 50% of the kinetic slide impact energy propagated outward in the impulse wave train. The applicability ranges of the classical nonlinear wave theories to landslide generated impulse waves were determined. The main wave characteristics were related to the landslide parameters driving the entire wave generation process. The slide Froude number was identified as the dominant parameter. The physical model results were compared to the giant rockslide generated impulse wave which struck the shores of the Lituya Bay, Alaska, in 1958.
Citations
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Journal ArticleDOI
TL;DR: In this article, a smooth and streamlined rigid body slides down a plane slope, starting from different initial submergence depths, and generates surface waves, different conditions of wave nonlinearity and dispersion are generated by varying the model slide initial depth.
Abstract: Large scale, three-dimensional, laboratory experiments are performed to study tsunami generation by rigid underwater landslides. The main purpose of these experiments is to both gain insight into landslide tsunami generation processes and provide data for subsequent validation of a three-dimensional numerical model. In each experiment a smooth and streamlined rigid body slides down a plane slope, starting from different initial submergence depths, and generates surface waves. Different conditions of wave nonlinearity and dispersion are generated by varying the model slide initial submergence depth. Surface elevations are measured with capacitance gauges. Runup is measured at the tank axis using a video camera. Landslide acceleration is measured with a microaccelerometer embedded within the model slide, and its time of passage is further recorded at three locations down the slope. The repeatability of experiments is very good. Landslide kinematics is inferred from these measurements and an analytic law of motion is derived, based on which the slide added mass and drag coefficients are computed. Characteristic distance and time of slide motion, as well as a characteristic tsunami wavelength, are parameters derived from these analyses. Measured wave elevations yield characteristic tsunami amplitudes, which are found to be well predicted by empirical equations derived in earlier work, based on two-dimensional numerical computations. The strongly dispersive nature and directionality of tsunamis generated by underwater landslides is confirmed by wave measurements at gauges. Measured coastal runup is analyzed and found to correlate well with initial slide submergence depth or characteristic tsunami amplitude.

195 citations


Cites background from "Near Field Characteristics of Lands..."

  • ...…done for 2D cases, either represented by solid bodies sliding down a plane slope (e.g., Wiegel, 1955; Iwasaki 1982; Heinrich, 1992; Watts, 1997, 1998, 2000; Watts et al.,2000; Grilli and Watts, 2005), or for landslides made of granular mterial (e.g., Watts, 1997; Fritz, 2002; Fritz et al., 2004)....

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  • ...The latter would be better modeled using small particles (e.g., Fritz et al.,2004)....

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Journal ArticleDOI
Abstract: On July 10, 1958, an earthquake Mw 8.3 along the Fairweather fault triggered a major subaerial landslide into Gilbert Inlet at the head of Lituya Bay on the southern coast of Alaska. The landslide impacted the water at high speed generating a giant tsunami and the highest wave runup in recorded history. The megatsunami runup to an elevation of 524 m caused total forest destruction and erosion down to bedrock on a spur ridge in direct prolongation of the slide axis. A cross section of Gilbert Inlet was rebuilt at 1∶675 scale in a two-dimensional physical laboratory model based on the generalized Froude similarity. A pneumatic landslide tsunami generator was used to generate a high-speed granular slide with controlled impact characteristics. State-of-the-art laser measurement techniques such as particle image velocimetry (PIV) and laser distance sensors (LDS) were applied to the decisive initial phase with landslide impact and wave generation as well as the runup on the headland. PIV provided instantaneous velocity vector fields in a large area of interest and gave insight into kinematics of wave generation and runup. The entire process of a high-speed granular landslide impact may be subdivided into two main stages: (a) Landslide impact and penetration with flow separation, cavity formation and wave generation, and (b) air cavity collapse with landslide run-out and debris detrainment causing massive phase mixing. Formation of a large air cavity — similar to an asteroid impact — in the back of the landslide is highlighted. A three-dimensional pneumatic landslide tsunami generator was designed, constructed and successfully deployed in the tsunami wave basin at OSU. The Lituya Bay landslide was reproduced in a three-dimensional physical model at 1∶400 scale. The landslide surface velocities distribution was measured with PIV. The measured tsunami amplitude and runup heights serve as benchmark for analytical and numerical models.

194 citations

01 Jan 2006
TL;DR: In this paper, the energy transfer from landslide motion to water motion was studied, i.e., the generation of tsunamis by submarine landslides, and it was shown that the energy can be transferred from landslide motions to water motions.
Abstract: Wave formation and propagation due to submarine landslides are complex phenomena that may be divided into four parts: Landslide dynamics, energy transfer from landslide motion to water motion, wave propagation in open water, and wave run-up along the shores. This paper focuses on the energy transfer from landslide motion to water motion, i.e. the generation of tsunamis by submarine landslides.

185 citations


Cites background from "Near Field Characteristics of Lands..."

  • ...Fritz et al. (2004) also found that rock slides with large volumes or high speeds bring along an air cushion around the sliding masses increasing the effective volume of the rock slide....

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  • ...This is demonstrated by the experiments of Fritz et al. (2004) who investigated wave generation by granular slides at laboratory scale, mainly for investigating rock slide generated tsunamis....

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Journal ArticleDOI
TL;DR: In this article, the authors report on numerical simulations of a tsunami that might result from the extreme case of a flank collapse of the Cumbre Vieja volcano at the La Palma Island, done by combining a multimaterial model for the wave generation with Boussinesq models for the far-field propagation.
Abstract: [1] The likelihood of a large scale tsunami from the La Palma Island is considered small by most. Nevertheless, the potential catastrophic consequences call for attention. Here we report on numerical simulations of a tsunami that might result from the extreme case of a flank collapse of the Cumbre Vieja volcano at the La Palma Island, done by combining a multimaterial model for the wave generation with Boussinesq models for the far-field propagation. Our simulations show that the slide speed is close to critical, effectively generating an initial wave of several hundred meters height. Our main focus is the wave propagation which is genuinely dispersive. In the far-field, propagation becomes increasingly complex due to the combined effects of dispersion, refraction, and interference in the direction of propagation. Constructive interference of the trailing waves are found to decrease the decay of the maximum amplitude with distance compared to classical asymptotic theory at transatlantic distances. Thus, the commonly used hydrostatic models fail to describe the propagation. Consequences of the La Palma scenario would be largest at the Canary Islands, but our findings also suggests that the whole central Atlantic would face grave consequences. However, the largest surface elevations are smaller than the most pessimistic reports found in literature. We also find undular bores towards the shorelines of America.

184 citations


Additional excerpts

  • ...Fully compressible flow models have been successful in modeling the 1952 Lituya Bay tsunami [Miller, 1960; Mader, 1999; Mader and Gittings, 2002], showing good agreement with both experimental data [Fritz et al., 2004] as well as observed runup....

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Journal ArticleDOI
TL;DR: In this article, a number of examples are presented to substantiate that submarine landslides have occurred along most continental margins and along several volcano flanks, and the need for data acquisition and analyses, laboratory experiments, and more sophisticated numerical modelling for improved understanding and hazard assessment of landslide tsunamis are elaborated.
Abstract: A number of examples are presented to substantiate that submarine landslides have occurred along most continental margins and along several volcano flanks. Their properties of importance for tsunami generation (i.e. physical dimensions, acceleration, maximum velocity, mass discharge, and travel distance) can all gain extreme values compared to their subaerial counterparts. Hence, landslide tsunamis may also be extreme and have regional impact. Landslide tsunami characteristics are discussed explaining how they may exceed tsunamis induced by megathrust earthquakes, hence representing a significant risk even though they occur more infrequently. In fact, submarine landslides may cause potentially extreme tsunami run-up heights, which may have consequences for the design of critical infrastructure often based on unjustifiably long return periods. Giant submarine landslides are rare and related to climate changes or glacial cycles, indicating that giant submarine landslide tsunami hazard is in most regions negligible compared to earthquake tsunami hazard. Large-scale debris flows surrounding active volcanoes or submarine landslides in river deltas may be more frequent. Giant volcano flank collapses at the Canary and Hawaii Islands developed in the early stages of the history of the volcanoes, and the tsunamigenic potential of these collapses is disputed. Estimations of recurrence intervals, hazard, and uncertainties with today’s methods are discussed. It is concluded that insufficient sampling and changing conditions for landslide release are major obstacles in transporting a Probabilistic Tsunami Hazard Assessment (PTHA) approach from earthquake to landslide tsunamis and that the more robust Scenario-Based Tsunami Hazard Assessment (SBTHA) approach will still be most efficient to use. Finally, the needs for data acquisition and analyses, laboratory experiments, and more sophisticated numerical modelling for improved understanding and hazard assessment of landslide tsunamis are elaborated.

177 citations


Cites background from "Near Field Characteristics of Lands..."

  • ...To this end, subaerial landslide and volcano collapses will always have a critical or supercritical nature which may enhance tsunami generation, causing huge waves locally (e.g. Abadie et al. 2012; Fritz et al. 2004)....

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References
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Journal ArticleDOI
TL;DR: In this article, the change of form of long waves advancing in a rectangular canal, and on a new type of long stationary waves were discussed, and a new model of long wave propagation was proposed.
Abstract: (1895). XLI. On the change of form of long waves advancing in a rectangular canal, and on a new type of long stationary waves. The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science: Vol. 39, No. 240, pp. 422-443.

3,400 citations

Book
01 Sep 1983
TL;DR: In this paper, the authors present an introduction to classical water wave theory for the college senior or first year graduate student, with a set of homework problems exercising and sometimes extending the material presented in the chapter.
Abstract: This book is intended as an introduction to classical water wave theory for the college senior or first year graduate student. The material is self-contained; almost all mathematical and engineering concepts are presented or derived in the text, thus making the book accessible to practicing engineers as well.The book commences with a review of fluid mechanics and basic vector concepts. The formulation and solution of the governing boundary value problem for small amplitude waves are developed and the kinematic and pressure fields for short and long waves are explored. The transformation of waves due to variations in depth and their interactions with structures are derived. Wavemaker theories and the statistics of ocean waves are reviewed. The application of the water particle motions and pressure fields are applied to the calculation of wave forces on small and large objects. Extension of the linear theory results to several nonlinear wave properties is presented. Each chapter concludes with a set of homework problems exercising and sometimes extending the material presented in the chapter. An appendix provides a description of nine experiments which can be performed, with little additional equipment, in most wave tank facilities.

2,339 citations


"Near Field Characteristics of Lands..." refers background in this paper

  • ...006 (Dean and Dalrymple 1991). The limiting wave steepness regarding wave breaking of progressive waves in intermediate water depths was given by Miche (1944) as...

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  • ...03 (Dean and Dalrymple 1991)....

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  • ...Therefore the wave envelope concept is introduced (Dean and Dalrymple 1991)....

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  • ...03 (Dean and Dalrymple 1991). Hence all waves generated by granular landslide impacts in the present study were nonlinear. The wave amplitude is not half the wave height in the encompassed nonlinear range. In the limiting shallow water case the stability of the wave profile depends on the relative wave height. The breaking (subscript b) criterion k in shallow water was defined from solitary wave theory by McCowan (1894) to k=Hb /h=0....

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Book ChapterDOI
01 Jul 2009
TL;DR: In this article, it was shown that the velocity of propagation of a series of oscillatory waves does not depend on the height of the waves, and that the extreme waves of such a series partake in some measure of the character of solitary waves and their height decreases as they proceed.
Abstract: I n the Report of the Fourteenth Meeting of the British Association for the Advancement of Science it is stated by Mr Russell, as a result of his experiments, that the velocity of propagation of a series of oscillatory waves does not depend on the height of the waves. A series of oscillatory waves, such as that observed by Mr Russell, does not exactly agree with what it is most convenient, as regards theory, to take as the type of oscillatory waves. The extreme waves of such a series partake in some measure of the character of solitary waves, and their height decreases as they proceed. In fact it will presently appear that it is only an indefinite series of waves which possesses the property of being propagated with a uniform velocity, and without change of form: at least this is the case when the waves are such as can be propagated along the surface of a fluid which was previously at rest. The middle waves, however, of a series such as that observed by Mr Russell agree very nearly with oscillatory waves of the standard form. Consequently, the velocity of propagation determined by the observation of a number of waves, according to Mr Russell's method, rmist be very nearly the same as the velocity of propagation of a series of oscillatory waves of the standard form, and whose length is equal to the mean length of the waves observed, which are supposed to differ from each other but slightly in length.

973 citations