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1.
The physical simulation of tsunami in the laboratory has taken a major leap forward with the construction and testing of a new wave generator, capable of recreating scaled tsunami waves. Numerical tools fail to reproduce tsunami nearshore and onshore processes well, and physical experiments in large scale hydraulic facilities worldwide have been limited to the generation of solitary waves as an (controversial) approximation for evolved forms of tsunami. The new concept in wave generation presented herein is born of collaboration between UCL's Earthquake and People Interaction Centre (EPICentre) and HR Wallingford. It allows for the first time the stable simulation of extremely long waves led either by a crest or a trough (depressed wave). This paper presents the working concepts behind the new wave generator and the first stages of testing for verifying its capacities and limitations. It is shown that the new wave generator can not only reproduce solitary waves and N-waves with large wavelengths, but also the 2004 Indian Ocean Tsunami as recorded off the coast of Thailand (“Mercator” trace). 相似文献
2.
The Okinawa Trench in the East China Sea and the Manila Trench in the South China Sea are considered to be the regions with high risk of potential tsunamis induced by submarine earthquakes. Tsunami waves will impact the southeast coast of China if tsunamis occur in these areas. In this paper, the horizontal two-dimensional Boussinesq model is used to simulate tsunami generation, propagation, and runnp in a domain with complex geometrical boundaries. The temporary varying bottom boundary condition is adopted to describe the initial tsunami waves motivated by the submarine faults. The Indian Ocean tsunami is simulated by the numerical model as a validation case. The time series of water elevation and runup on the beach are compared with the measured data from field survey. The agreements indicate that the Boussinesq model can be used to simulate tsunamis and predict the waveform and runup. Then, the hypothetical tsunamis in the Okinawa Trench and the Manila Trench are simulated by the numerical model. The arrival time and maximum wave height near coastal cities are predicted by the model. It turns out that the leading depression N-wave occurs when the tsunami propagates in the continental shelf from the Okinawa Trench. The scenarios of the tsunami in the Manila Trench demonstrate significant effects on the coastal area around the South China Sea. 相似文献
3.
This paper presents a new submarine landslide model based on the non-hydrostatic wave model NHWAVE of Ma et al. (2012). The landslide is modeled as a water–sediment mixture. The dense plume is driven by baroclinic pressure forcing introduced by spatial density variations. The model is validated using laboratory measurements of turbidity currents and of water wave generation by a granular landslide. The model is then utilized to study the dependence of landslide motion and associated tsunami wave generation on parameters including sediment settling velocity, initial depth of the landslide and slide density. Model results show that the slide motion and water waves which it generates are both sensitive to these parameters. The relative tsunamigenic response to rigid and deformable landslides of equal initial geometry and density is also examined. It is found that the wave energy is mostly concentrated on a narrow band of the dominant slide direction for the waves generated by rigid landslides, while directional spreading is more significant for waves generated by deformable landslides. The deformable landslide has larger speed and acceleration at the early stage of landslide, resulting in larger surface waves. The numerical results indicate that the model is capable of reasonably simulating tsunami wave generation by submarine landslides. 相似文献
4.
根据渤海区域地质断层特征和历史地震活动规律,分析得出渤海内潜在最大震级上限为8.1级,并对该海啸源可能的两组震源机制分别进行了数值模拟。模拟结果显示：渤海局部区域海啸波幅最大可达 1.5 m,最大流速可达2.8~3.0 m/s,具备造成灾害损失的风险。在该海啸源情景下,渤海海盆内易激发长期的水位自由振荡,部分区域水位振荡可持续 20 h以上,振荡波幅的大小与海啸首波波幅相当或更大。基于快速傅里叶变换方法对海啸波进行频谱分析,部分长周期频谱成分满足区域固有共振特征。因此,渤海内一旦发生海啸,不仅要关注海啸首波可能造成的灾害性影响,还要密切关注海啸首波到达后,可能产生的长时间、长周期的海啸波共振以及往复式海啸流造成的影响。 相似文献
5.
“3.11”日本地震海啸及南海和琉球群岛假想地震海啸对福建近海影响的数值模拟 总被引：1，自引：0，他引：1
福建地处西北太平洋沿岸,在环太平洋地震带附近,是海啸灾害潜在风险区.＂3.11＂日本地震海啸,福建沿岸验潮站就监测到其海啸波.利用CTSU地震海啸数值模式,模拟了＂3.11＂日本地震海啸对福建近海的影响,模拟结果与实况较吻合.同时,利用该数值模式模拟分析了可能来自于琉球群岛和南海附近海域的地震海啸对福建近海的影响,分析表明,如果在琉球群岛海域（28.0°N,129.0°E）发生8.8级地震,引发的海啸波将在4.5 h左右抵达福建北部海岸,最大海啸波幅可达2 m;如果在马尼拉海沟附近海域（17.5°N,119.0°E）发生8.8级地震,引发的海啸波将在4 h左右抵达福建南部海岸,最大海啸波幅可达3 m,均会给福建沿海地区带来灾害性影响.为此,本文亦针对性提出了防范地震海啸的一些措施与建议,为福建省海洋防灾减灾提供参考. 相似文献
6.
在COMCOT海啸数学模型中加入潮汐边界条件,建立了东中国海天文潮与海啸耦合数学模型。在琉球海沟内侧设计震级为7.6级的海底地震,根据地震板块的错动方向不同,设计正波先行与负波先行两种海啸波,通过调整海啸波发生时间,使海啸波波峰遭遇温州湾天文高潮位。将天文潮与海啸耦合模型计算结果与线性叠加计算结果进行比较,结果表明:无论正波先行还是负波先行,天文潮与海啸耦合计算相比线性叠加的结果,海啸波的到达时间均有所提前;而从海啸波波高来看,线性叠加的计算结果则比耦合计算结果偏高。 相似文献
7.
The present study focused on tracing tsunami-drifted objects under a real tsunami based on an integrated numerical method. Instead of a solitary wave that is much shorter and steeper than real-world tsunami waves, an extra-long tsunami wave is represented here in a nearshore region using a new approach. To this end, propagation of a seismic tsunami from the source to the nearshore region was simulated using two-dimensional depth-averaged equations. When the waves reached the target coastal area, the time series of the free surface of the tsunami was approximated by a theoretical relation based on a combination of several solitons, which were then used to solve the linearized trajectory equation of the wave-maker to generate the intended time series of the tsunami wave. Finally, in a nearshore model, the movement of drifted bodies under the generated tsunami wave was simulated based on the smoothed-particle hydrodynamics (SPH) method. In order to verify the accuracy of the proposed method in tracing the drifted bodies under a real tsunami, the giant fish-oil tank, which was transported about 300 m during the 2011 Tohoku tsunami of Japan, was selected as the benchmark. The results demonstrate that the time series of the long tsunami wave was successfully generated by the piston wave-maker in the GPU-based SPH model, and the proposed approach can be regarded as a suitable alternative for reproduction of a real tsunami. The results also showed that the simulated fish-oil tank properly followed the estimated trajectory in Ishinomaki but it was transported more than the reported distance, which was expected due to absence of a holding connection between the tank and the ground in the SPH model. It should be emphasized that this study is one of the first studies on three-dimensional tracing of a tsunami-drifted body during a real event, and the tracing can be more accurate in further simulations by applying higher-resolution topography data and faster computation systems that help include more details in the nearshore model. 相似文献
8.
While the destruction caused by a tsunami can vary significantly owing to near- and onshore controls, we have only a limited quantitative understanding of how different local parameters influence the onshore response of tsunamis. Here, a numerical model based on the non-linear shallow water equations is first shown to agree well with analytical expressions developed for periodic long waves inundating over planar slopes. More than 13,000 simulations are then conducted to examine the effects variations in the wave characteristics, bed slopes, and bottom roughness have on maximum tsunami run-up and water velocity at the still water shoreline. While deviations from periodic waves and planar slopes affect the onshore dynamics, the details of these effects depend on a combination of factors. In general, the effects differ for breaking and non-breaking waves, and are related to the relative shift of the waves along the breaking–non-breaking wave continuum. Variations that shift waves toward increased breaking, such as steeper wave fronts, tend to increase the onshore impact of non-breaking waves, but decrease the impact of already breaking waves. The onshore impact of a tsunami composed of multiple waves can be different from that of a single wave tsunami, with the largest difference occurring on long, shallow onshore topographies. These results demonstrate that the onshore response of a tsunami is complex, and that using analytical expressions derived from simplified conditions may not always be appropriate. 相似文献
9.
A proper design of offshore and coastal structures requires further knowledge about extreme wave events. Such waves are highly nonlinear and may occur unexpectedly due to diverse reasons. One of these reasons is wave–wave interaction and the wave focusing technique represents one option to generate extreme wave events in the laboratory. The underlying mechanism is the superimposition and phasing of wave components at a predefined location. To date, most of the existing methods to propagate target wave profile backwards to the position of the wave generator apply linear wave theory. The problem is that the generated waves with different frequencies generate new components which do not satisfy the linear dispersion relation. As a result, small changes in the wave board control signal generally induce large and random shifts in the resulting focused wave. This means that iterations are necessary to get the required wave profile at the correct position in the flume. In this study, a Self Correcting Method (SCM) is applied to optimize the control signal of the wave maker in a Numerical Wave Tank (NWT). The nonlinearities are included in the control signal and accurate wave focusing is obtained irrespective of the prevailing seabed topography (horizontal or sloping) and type of structure (reflective or absorbing). The performance of the proposed SCM is numerically investigated for a wide variety of scenarios and validated by scale model tests in the Large Wave Flume (Großer Wellen Kanal, GWK), Hannover, Germany. Moreover, the application of the proposed SCM in the Numerical Wave Tank to generate a tsunami at a predefined position and the comparison of the results with the time series recorded in the Pago Pago harbour (Samoa) is very encouraging. The strengths and limitations of the proposed SCM are discussed, including the potential for further developments. 相似文献
10.
The process of tsunami generation by the moving horizontal bottom displacement is studied numerically. The influence produced by the displacement rate and the range of the run on the parameters of the wave generated is studied. A comparison with the results derived using the linear theory of long waves is made.Translated by Mikhail M. Trufanov. 相似文献
11.
This paper presents optical measurements of tsunami inundation through an urban waterfront in a laboratory wave basin. The physical model was constructed at 1:50 scale and was an idealization of the town of Seaside, Oregon. The fixed-bed model was designed to study the initial inundation zone along an urban waterfront, such that the flow around several large buildings could be observed. This paper presents an analysis of the optical measurements made with two overhead video cameras, focusing on tracking the leading edge of the tsunami inundation through the urban waterfront and quantifies the accuracy of the algorithm used to track the edge. The results show that the methodology provides high-resolution information in both time and space of the leading edge position, and that these data can be used to quantify the influence of large macro-roughness features on the tsunami inundation processes in laboratory settings. The overall effect of the macro-roughness was to decrease the bore propagation speed relative to the control section with no macro-roughness. The bore speed could be reduced by as much as 40% due to the presence of the macro-roughness relative to the control section. 相似文献
12.
Peitao Wang Zhiyuan Ren Lining Sun Jingming Hou Zongchen Wang Ye Yuan Fujiang Yu 《海洋学报(英文版)》2021,40(11):11-30
The systematic discrepancies in both tsunami arrival time and leading negative phase (LNP) were identified for the recent transoceanic tsunami on 16 September 2015 in Illapel, Chile by examining the wave characteristics from the tsunami records at 21 Deep-ocean Assessment and Reporting of Tsunami (DART) sites and 29 coastal tide gauge stations. The results revealed systematic travel time delay of as much as 22 min (approximately 1.7％ of the total travel time) relative to the simulated long waves from the 2015 Chilean tsunami. The delay discrepancy was found to increase with travel time. It was difficult to identify the LNP from the near-shore observation system due to the strong background noise, but the initial negative phase feature became more obvious as the tsunami propagated away from the source area in the deep ocean. We determined that the LNP for the Chilean tsunami had an average duration of 33 min, which was close to the dominant period of the tsunami source. Most of the amplitude ratios to the first elevation phase were approximately 40％, with the largest equivalent to the first positive phase amplitude. We performed numerical analyses by applying the corrected long wave model, which accounted for the effects of seawater density stratification due to compressibility, self-attraction and loading (SAL) of the earth, and wave dispersion compared with observed tsunami waveforms. We attempted to accurately calculate the arrival time and LNP, and to understand how much of a role the physical mechanism played in the discrepancies for the moderate transoceanic tsunami event. The mainly focus of the study is to quantitatively evaluate the contribution of each secondary physical effect to the systematic discrepancies using the corrected shallow water model. Taking all of these effects into consideration, our results demonstrated good agreement between the observed and simulated waveforms. We can conclude that the corrected shallow water model can reduce the tsunami propagation speed and reproduce the LNP, which is observed for tsunamis that have propagated over long distances frequently. The travel time delay between the observed and corrected simulated waveforms is reduced to <8 min and the amplitude discrepancy between them was also markedly diminished. The incorporated effects amounted to approximately 78％ of the travel time delay correction, with seawater density stratification, SAL, and Boussinesq dispersion contributing approximately 39％, 21％, and 18％, respectively. The simulated results showed that the elastic loading and Boussinesq dispersion not only affected travel time but also changed the simulated waveforms for this event. In contrast, the seawater stratification only reduced the tsunami speed, whereas the earth's elasticity loading was responsible for LNP due to the depression of the seafloor surrounding additional tsunami loading at far-field stations. This study revealed that the traditional shallow water model has inherent defects in estimating tsunami arrival, and the leading negative phase of a tsunami is a typical recognizable feature of a moderately strong transoceanic tsunami. These results also support previous theory and can help to explain the observed discrepancies. 相似文献
13.
During the last few years it has been shown that the results of model tests of harbour basins and moored ships are highly dependent on the correct reproduction of wave groups and the attached long waves. Although these bounded long waves are of second order and thus of a rather limited height, resonance and shoaling effects can increase their influence on the results of model investigations. In traditional first order wave generation, the boundary conditions at the wave board are not fulfilled for the bounded long waves, and consequently various spurious, free long waves are unintentionally produced. This paper outlines the general equations and the solution for a rotating and translating wave board. The translatory case is treated in detail, i.e. a physical interpretation of all the second order terms is given, and an approximate control signal for the suppression of spurious long waves for practical use is described. Finally, laboratory experiments successfully verify the various long wave terms and the effectiveness of the suppression terms. 相似文献
14.
本文基于2017年634幅MODIS影像分析了安达曼海3个典型区域的内波空间分布特征,定量统计了波峰线长度、波包面积等特征参数,利用射线追踪法探讨了内波的潜在激发源并推算了内波的生成周期。研究表明,安达曼海北部海域的内波空间尺度较小,前导波波峰线的平均长度约为107 km,平均波包面积约为1 860 km2,内波的传播方向主要为东向以及西南向。安达曼海中部海域内波前导波波峰线的平均长度约为133 km,平均波包面积约为3 503 km2,超过70%的内波沿东偏北方向传播。苏门答腊岛北部海域内波前导波波峰线的平均长度约为131 km,平均波包面积约为2 997 km2,内波的传播方向主要为东向、东北向及东南向。安达曼海共有7个潜在内波激发源,内波的生成时间间隔介于11.5～13 h,具有明显的半日周期特征。 相似文献
15.
The linear model of long waves is used for the evaluation of the parameters of tsunami waves along the South Coast of Crimea,
in the near-Kerch zone, and near the northeast coast of the Black Sea. Our numerical investigations are carried out for 24
probable locations of the elliptic zones of tsunami generation over the continental slope of the basin. The amplitude characteristics
of tsunamis are computed for 27 sites of the Black-Sea coast. It is shown that significant strengthening of tsunami waves
is possible in the course of their propagation toward the coast. The highest waves are formed at the sites of the coast closest
to the seismic source. The dependence of the intensity of tsunami waves along the Black-Sea coast on the location of the seismic
source and its magnitude is analyzed. 相似文献
16.
M. A. Nosov 《Izvestiya Atmospheric and Oceanic Physics》2014,50(5):474-484
This review summarizes the concepts of seismogenic tsunami waves. Principles of short-term tsunami forecasting and tsunami recording systems are discussed. The traditional approach to describing tsunami generation by earthquakes is outlined and its drawbacks are analyzed. The main and secondary effects are distinguished which are responsible for the formation of waves by underwater earthquakes. The existing numerical codes of tsunami dynamics are described. 相似文献
17.
海啸波传播的线性和非线性特征及近海陆架效应影响的数值研究 总被引：3，自引：2，他引：1
浅水方程被广泛应用于海啸预警报业务及研究,而针对线性浅水方程与非线性浅水方程在不同海区水深地形条件下的适用范围、计算效率问题是海啸研究人员急需了解的。本文应用基于浅水方程的海啸数值预报模型就海啸波在南海、东海传播的线性、非线性特征以及陆架对其传播之影响进行了数值分析研究。海啸波在深水的传播表征为强线性特征,此时线性系统对海啸波幅的模拟计算具有较高的精度和效率,而弱的非线性特征及弱的色散特征对海啸波幅的预报影响甚微,可以忽略不计。海啸波传播至浅水大陆架后受海底坡度变化、海底粗糙度等因素影响,波动的非线性效应迅速传播、积累,与线性浅水方程计算的海啸波相比表现出较大差异,主要表现为:在南海区,水深小于100m时,海啸波首波以后的系列波动非线性特征比较明显,两者波幅差别较大,但首波波幅的区别不大,因此对于该区域在不考虑海啸爬高的情况下,应用线性系统计算得到的海啸波幅也可满足海啸预警报的要求;在东海区由于陆架影响,海啸波非线性特征明显增强,水深小于100m区域,首波及其后系列波波幅均差异较大,故在该区域必须考虑海啸波非线性作用。本文就底摩擦项对海啸波首波波幅的影响进行了数值对比分析,结果表明:底摩擦作用对海啸波首波波幅影响仅作用于小于100m水深。最后,该文通过敏感性试验,初步分析了陆架宽度及陆架边缘深度对海啸波波幅的影响,得出海啸波经陆架传播共振、变形后,海啸波幅的放大或减小与陆架的宽度及陆架边缘水深有关。 相似文献
18.
Solitary waves have been commonly used as an initial condition in the experimental and numerical modelling of tsunamis for decades. However, the main component of a tsunami waves acts at completely different spatial and temporal scales than solitary waves. Thus, use of solitary waves as approximation of a tsunami wave may not yield realistic model results, especially in the coastal region where the shoaling effect restrains the development of the tsunami wave. Alternatively, N-shaped waves may be used to give a more realistic approximation of the tsunami wave profile. Based on the superposition of the sech2(*) waves, the observed tsunami wave profile could be approximated with the N-shaped wave method, and this paper presents numerical simulation results based on the tsunami-like wave generated based on the observed tsunami wave profile measured in the Tohoku tsunami. This tsunami-like wave was numerically generated with an internal wave source method based on the two-phase incompressible flow model with a Volume of Fluid (VOF) method to capture the free surface, and a finite volume scheme was used to solve all the governing equations. The model is first validated for the case of a solitary wave propagating within a straight channel, by comparing its analytical solutions to model results. Further, model comparisons between the solitary and tsunami-like wave are then made for (a) the simulation of wave run-up on shore and (b) wave transport over breakwater. Comparisons show that use of these largely different waveform shapes as inputs produces significant differences in overall wave evolution, hydrodynamic load characteristics as well as velocity and vortex fields. Further, it was found that the solitary wave uses underestimated the total energy and hence underestimated the run-up distance. 相似文献
19.
2015年9月16日22时54分（当地时间）智利中部近岸发生Mw8.3级地震,震源深度25 km。同时,强震的破裂区长200 km,宽100 km,随之产生了中等强度的越洋海啸。海啸影响了智利沿岸近700 km的区域,局部地区监测到近5 m的海啸波幅和超过13 m的海啸爬坡高度。太平洋区域的40多个海啸浮标及200多个近岸潮位观测站详细记录了此次海啸的越洋传播过程,为详细研究此次海啸近场及远场传播及演化规律提供了珍贵的数据。本文选择有限断层模型和自适应网格海啸数值模型建立了既可以兼顾越洋海啸的计算效率又可以实现近场海啸精细化模拟的高分辨率海啸模型。模拟对比分析了海啸的越洋传播特征,结果表明采用所建立的模型可以较好地再现远场及近场海啸特征,特别是对近场海啸的模拟结果非常理想。表明有限断层可以较好地约束近场、特别是局部区域的破裂特征,可为海啸预警提供更加精确的震源信息,结合高分辨率的海啸数值预报模式实现海啸传播特征的精细化预报。本文结合观测数据与数值模拟结果初步分析了海啸波的频散特征及其对模型结果的影响。同时对观测中典型的海啸波特征进行的简要的总结。谱分析结果表明海啸波的能量主要分布在10~50 min周期域内。这些波特征提取是现行海啸预警信息中未涉及,但又十分重要的预警参数。进一步对这些波动特征的详细研究将为海啸预警信息及预警产品的完善提供技术支撑。 相似文献