Tsunami Simulation Model Research Articles

Tsunami inundation maps for the northwest of Peninsular Malaysia and demarcation of affected electrical assets.

The massive destruction and loss caused by the 2004 Sumatra-Andaman tsunami were attributed to the lack of knowledge on tsunami and low regional detection and communication systems for early warning in that region. This study aimed to identify locations at risk of impending tsunami from Andaman Sea for the safety of community and proper development planning at the coastal areas by providing an updated and revised inundation maps. The last study on this area was conducted several years ago which open the possibility to new findings. Generated by tsunami simulation models, the maps illustrate the extent and level of inundation to which the coastal community and infrastructure would be subjected. As a result of coastal changes and availability of better topographic data, the existing inundation maps for the coastal areas of northwest Peninsular Malaysia at risk to impending tsunami from the Andaman Sea are revised. This paper documented the computational setup leading to the generation of the revised inundation maps. The tsunami simulation model TUNA was used to simulate the generation, propagation, and subsequent run-up and inundation of tsunamis triggered by earthquakes of moment magnitudes (Mw) 8.5, 9.0, and 9.25 along the Sunda Trench. From the simulations, it was found that at Mw 9.25, Balik Pulau, Pulau Pinang would be subjected to inundation of as far as 3.47km with 5.40-m-deep inundation at the highest section.

Assessment Of Tsunami Hazard In Sabah – Level Of Threat, Constraints And Future Work

The coastal areas of Sabah are exposed to far-field earthquake-induced tsunamis that could be generated along the trenches of Manila, Negros, Sulu, Cotabato, Sangihe and North Sulawesi. Tsunami simulation models from these trenches indicated that tsunami waves can reach the coast of Sabah between 40 and 120 minutes with tsunami wave heights reaching up to 3 m near the coast. The level of tsunami threat is high in southeast Sabah due to its narrow continental shelf and proximity to tsunami source in the North Sulawesi Trench. The level of tsunami threat is moderate in north and east Sabah due to their proximity to tsunami source in the Sulu Trench. The level of tsunami threat is low in west Sabah due to its distant location to tsunami source from the Manila Trench. While tsunamis cannot be prevented, its impact on human life and property can be reduced through proper assessment of its threat using tsunami simulation models. Unfortunately, constraints remain in producing a reliable tsunami inundation models due to the lack of high-resolution topography and bathymetry data in Sabah and surrounding seas. It would be helpful if such data can be acquired by the relevant government agencies, at least first, in high threat-level areas, such as Tawau and Semporna districts. In order to properly plan mitigation measures tsunami risk mapping should be intensified in high threat-level areas. The locations of settlements (including water villages), population concentrations, types of buildings and houses, road system, drainage system, harbours, jetties and vegetations (including mangroves) need to be mapped in great detail. Based on the detailed tsunami risk map, targeted vulnerable communities could be given continuous and intensive education and awareness on basic tsunami science and tsunami hazard preparedness.

Seiche Effects in Lake Tekapo, New Zealand, in an Mw8.2 Alpine Fault Earthquake

This study investigates the potential for seismic seiches in Lake Tekapo, New Zealand, triggered by ground shaking from an Mw8.2 Alpine Fault earthquake. Synthetic ground motions are used as a forcing boundary to drive lake water motions by further developing a tsunami simulation model—COMCOT—and coupling it with earthquake simulation model outputs. Our modelling results reveal that lake water oscillations are mobilised immediately by the ground movement and further amplified by cross-lake seiches. Amplitudes of lake oscillations can reach up to 4.0 m in the lake’s narrow southern arm, over 1.0 m along the shore of Lake Tekapo township, and about 1.5–2.5 m along many other parts of the lake shore. Large-amplitude water oscillations quickly attenuate in the first 5–10 min after the earthquake due to their relatively short periods, while long-period oscillations continue for a long time, albeit with much smaller amplitudes. Spectral analysis clearly reveals that the ground motions trigger both fundamental and higher modes in the lake whose oscillation periods are consistent with theoretical estimates. We find that large-amplitude lake water oscillations are better correlated with low-frequency, less energetic ground motion content than with high-frequency large-amplitude ground motions. Ground motion-triggered lake oscillations are large enough to pose potential threat to tourists, residents, boats and infrastructure both in the lake water and onshore near the waterfront. In contrast, vertical co-seismic displacements in the lake area, the conventional mechanism for tsunami generation, are too small to trigger tsunami waves of concern.

Rational Evaluation Methods of Topographical Change and Building Destruction in the Inundation Area by a Huge Tsunami

In the case of huge tsunamis, such as the 2004 Great Indian Ocean Tsunami and 2011 Great East Japan Tsunami, the damage caused by ground scour is serious. Therefore, it is important to improve prediction models for the topographical change of huge tsunamis. For general models that predict topographical change, the flow velocity distribution of a flood region is calculated by a numerical model based on a nonlinear long wave theory, and the distribution of bed-load rates is calculated using this velocity distribution and an equation for evaluating bed-load rates. This bed-load rate equation usually has a coefficient that can be decided using verification simulations. For the purpose, Ribberink’s formula has high reproducibility within an oscillating flow and was chosen by the authors. Ribberink’s formula needs a bed-load transport coefficient that requires sufficient verification simulations, as it consumes plenty of time and money to decide its value. Therefore, the authors generated diagrams that can define the suitable bed-load coefficient simply using the data acquired from hydraulic experiments on a movable bed. Subsequently, for the verification purpose of the model, the authors performed reproduced simulations of topography changes caused by the 2011 Great East Japan Tsunami at some coasts in Northern Japan using suitable coefficients acquired from the generated diagrams. The results of the simulations were in an acceptable range. The authors presented the preliminary generated diagrams of the same methodology but with insubstantial experimental data at the time at the International Society of Offshore and Polar Engineers (ISOPE), (2018 and 2019). However, in this paper, an adequate amount of data was added to the developed diagrams based on many hydraulic experiments to further raise their reliability and their application extent. Furthermore, by reproducing the tsunami simulation on the Sendai Natori coast of Japan, the authors determined that the impact of total bed-load transport was much bigger than that of suspension loads. Besides, the simulation outputs revealed that the mitigation effect of the cemented sand and gravel (CSG) banks and artificial refuge hills reduced tsunami damage on Japan’s Hamamatsu coast. Since a lot of buildings and structures in the inundation area can be destroyed by tsunamis, building destruction design was presented in this paper through an economy and simplified state. Using the proposed tsunami simulation model, we acquired the inundation depth at any specific time and location within the inundated area. Because the inundation breadth due to a huge tsunami can extend kilometers toward the inland area, the evaluation of building destruction is an important measure to consider. Therefore, the authors in this paper presented useful threshold diagrams to evaluate building destruction with an easy and cost-efficient state. The threshold diagrams of “width of a pillar” for buildings or “width of concrete block walls” not breaking to each inundation height were developed using the data of damages due to the 2011 Great East Japan Tsunami.

Analysis and modeling of a landslide-induced tsunami-like wave across the Truong river in Quang Nam province, Vietnam

Landslide-induced waves are one of the most disastrous hazards that can post a great threat to human lives and properties. At about 4:00 pm, 5 November 2017, a landslide-induced tsunami-like wave suddenly occurred across the Truong river in Bac Tra My District, Quang Nam province, Vietnam. The water wave destroyed six houses at the opposite bank and caused one person dead and three others injured. This study seeks to investigate the initiation mechanism and process of the landslide and its impulse wave. First, we examined landslide characteristics through site investigations, unmanned aerial vehicle (UAV) surveys, and laboratory testing with a series of standard geotechnical tests on collected soil samples. Then, the initiation and motion of the rainfall-induced landslides were reproduced by the integrated landslide simulation model (LS-RAPID). Finally, a combined computer simulation of the landslide motion and its impulse wave was performed by using a landslide-induced tsunami simulation model (LS-Tsunami). In which, output data from the LS-RAPID was used as input parameters for LS-Tsunami. The analysis shows that the rainfall with very high intensity in a short-time period was the triggering factor of the landslide, which is common factor in the study area. The 12-, 24-, and 48-h accumulative precipitation prior to the landslide recorded to 530, 760, and 950 mm, respectively. In addition, the rainfall trigger presented a typical pattern of rainstorm events in a long duration. Simulation results show that the impulse wave was generated by the landslide mass rapidly entering the river, crossing the river, and directly causing the disastrous damage to the resident area opposite site of the fail slope. The landslide moved down at a maximum speed of 16.4 m/s when its body approached the water surface and generated a maximum wave height of 5 m. There is good agreement between the observed geomorphic evidences and water traces on the site and simulation results of the landslide and its impulse wave. The paper provides a good case study on the understanding of the mechanism and dynamic process of the whole event that significantly contribute to potential landslide hazard assessment and future disaster mitigation in the area.

Ex post analysis of engineered tsunami mitigation measures in the town of Dichato, Chile

Due to Chile’s notorious and frequent seismic activity, earthquake- and tsunami-related studies have become a priority in the interest of developing effective countermeasures to mitigate their impacts and to improve the country’s resilience. Mitigation measures are key to accomplish these objectives. Therefore, this investigation adopts a tsunami damage assessment framework to evaluate the direct benefits of tsunami mitigation works implemented by the Chilean government in the town of Dichato in the aftermath of the 2010 tsunami. We perform an ex post analysis of the potential damage reduction produced by these works studying what would have been the consequences on the built environment if they were in place for the tsunami that hit this area after the Maule earthquake in February 27, 2010. We use state-of-the-art tsunami simulation models at high resolution to assess the reduction in tsunami intensity measures, which serve as input to evaluate the benefit from averted damage against the costs of the mitigation measures. The obtained results show a reduction in the flooded area and a delay in the arrival times for the first smaller tsunami waves, but a negligible damage reduction when confronted to the largest waves. In conclusion, the tsunami mitigation measures would not have been effective to reduce the impact of the tsunami generated by the Maule earthquake in the town of Dichato, but could have had a benefit in retarding the inundation of low-land areas for the first smaller tsunami waves. The latter suggests that these works might be useful to mitigate storm waves or tsunamis of much smaller scales than the one that hit central-south Chile in 2010.

Tsunami run-up and inundation along the coast of Sabah and Sarawak, Malaysia due to a potential Brunei submarine mass failure.

Submarine landslides, also known as submarine mass failures (SMFs), are major natural marine disasters that could critically damage coastal facilities such as nuclear power plants and oil and gas platforms. It is therefore essential to investigate submarine landslides for potential tsunami hazard assessment. Three-dimensional seismic data from offshore Brunei have revealed a giant seabed mass deposited by a previous SMF. The submarine mass extends over 120km from the continental slope of the Baram Canyon at 200m water depth to the deep basin floor of the Northwest Borneo Trough. A suite of in-house two-dimensional depth-averaged tsunami simulation model TUNA (Tsunami-tracking Utilities and Application) is developed to assess the vulnerability of coastal communities in Sabah and Sarawak subject to potential SMF tsunami. The submarine slide is modeled as a rigid body moving along a planar slope with the center of mass motion parallel to the planar slope and subject to external forces due to added mass, gravity, and dissipation. The nonlinear shallow water equations are utilized to simulate tsunami propagation from deepwater up to the shallow offshore areas. A wetting-drying algorithm is used when a tsunami wave reaches the shoreline to compute run up of tsunami along the shoreline. Run-up wave height and inundation maps are provided for seven densely populated locations in Sabah and Sarawak to highlight potential risks at each location, subject to two scenarios of slide slopes: 2° and 4°. The first wave may arrive at Kudat as early as 0.4h after the SMF, giving local communities little time to evacuate. Over a small area, maximum inundated depths reaching 20.3m at Kudat, 26.1m at Kota Kinabalu, and 15.5m at Miri are projected, while the maximum inundation distance of 4.86km is expected at Miri due to its low-lying coast. In view of the vulnerability of some locations to the SMF tsunami, it is important to develop and implement community resilience program to reduce the potential damage that could be inflicted by SMF tsunamis.

Implementation of Algorithm for Satellite-Derived Bathymetry using Open Source GIS and Evaluation for Tsunami Simulation

Accurate and high resolution bathymetric data is a necessity for a wide range of coastal oceanographic research topics. Active sensing methods, such as ship-based soundings and Light Detection and Ranging (LiDAR), are expensive and time consuming solutions. Therefore, the significance of Satellite-Derived Bathymetry (SDB) has increased in the last ten years due to the availability of multi-constellation, multi-temporal, and multi-resolution remote sensing data as Open Data. Effective SDB algorithms have been proposed by many authors, but there is no ready-to-use software module available in the Geographical Information System (GIS) environment as yet. Hence, this study implements a Geographically Weighted Regression (GWR) based SDB workflow as a Geographic Resources Analysis Support System (GRASS) GIS module (i.image.bathymetry). Several case studies were carried out to examine the performance of the module in multi-constellation and multi-resolution satellite imageries for different study areas. The results indicate a strong correlation between SDB and reference depth. For instance, case study 1 (Puerto Rico, Northeastern Caribbean Sea) has shown an coefficient of determination (R2) of 0.98 and an Root Mean Square Error (RMSE) of 0.61 m, case study 2 (Iwate, Japan) has shown an R2 of 0.94 and an RMSE of 1.50 m, and case study 3 (Miyagi, Japan) has shown an R2 of 0.93 and an RMSE of 1.65 m. The reference depths were acquired by using LiDAR for case study 1 and an echo-sounder for case studies 2 and 3. Further, the estimated SDB has been used as one of the inputs for the Australian National University and Geoscience Australia (ANUGA) tsunami simulation model. The tsunami simulation results also show close agreement with post-tsunami survey data. The i.mage.bathymetry module developed as a part of this study is made available as an extension for the Open Source GRASS GIS to facilitate wide use and future improvements.

A new landslide-induced tsunami simulation model and its application to the 1792 Unzen-Mayuyama landslide-and-tsunami disaster

By combining landslide dynamics research and tsunami research, we present an integrated series of numerical models quantitatively simulating the complete evolution of a landslide-induced tsunami. The integrated model simulating the landslide initiation and motion uses measured landslide dynamic parameters from a high-stress undrained dynamic-loading ring shear apparatus. It provides the numerical data of a landslide mass entering and moving under water to the tsunami simulation model as the trigger of tsunami. The series of landslide and tsunami simulation models were applied to the 1792 Unzen-Mayuyama megaslide and the ensuing tsunami disaster, which is the largest landslide disaster, the largest volcanic disaster, and the largest landslide-induced tsunami disaster to have occurred in Japan. Both the 1792 megaslide and the tsunami portions of the disaster are well documented, making this an excellent test of the reliability and precision of the new simulation model. The simulated tsunami heights at the coasts well match the historical tsunami heights recorded by “Tsunami-Dome-Ishi” (a stone showing the tsunami reaching point) and memorial stone pillars.

格子ボルツマン法による津波数値解析に向けた無反射透過境界条件の基礎的検討

Lattice Boltzmann Method (LBM) is one of the new, robust and efficient Computational Fluid Dynamics (CFD) solvers. One of the key features of LBM is that implementation in parallel computing is more efficient compared with the other conventional CFD solvers. In the current study, we developed a novel Tsunami simulation model applying Impedance boundary condition for offshore non-reflecting boundary to Subgrid-scale LBM based on Shallow Water Equations. The model was tested in the benchmark with solitary wave incident waves. As a result, the model can reduce amount of wave reflection compared with the conventional non-reflective boundary condition based on linear long-wave approximation in the Finite Difference Method. Through the model verification, we found that Impedance boundary condition has a sufficient accuracy for Tsunami offshore non-reflecting boundary condition.

Simulation of distant tsunami propagation with a radial loading deformation effect

A simple parameterization of the loading deformation of the seafloor is incorporated into a tsunami simulation model in order to realistically calculate tsunami travel time, especially at regions far from the source. The parameterization uses one scalar parameter that is optimized effectively by far-field, deep-sea records of recent giant tsunamis: the 2011 Tohoku and the 2010 Chilean tsunamis. Using this parameterization with the optimal values, the observed tsunamis are realistically simulated in both near and far fields. The optimal values seem equivalent for both giant tsunamis, and are relatively smaller than those previously verified for ocean tide modeling, which is reasonable because of the shorter wavelengths of tsunamis.

動的アダプティブグリッド法を用いた有限体積法による津波計算モデル

動的アダプティブグリッド法を用いた有限体積法による津波計算モデル

Comparison of the seafloor displacement from uniform and non-uniform slip models on tsunami simulation of the 2011 Tohoku–Oki earthquake

The numerical simulations of recent tsunami caused by 11 March 2011 off-shore Pacific coast of Tohoku–Oki earthquake (Mw 9.0) using diverse co-seismic source models have been performed. Co-seismic source models proposed by various observational agencies and scholars are further used to elucidate the effects of uniform and non-uniform slip models on tsunami generation and propagation stages. Non-linear shallow water equations are solved with a finite difference scheme, using a computational grid with different cell sizes over GEBCO30 bathymetry data. Overall results obtained and reported by various tsunami simulation models are compared together with the available real-time kinematic global positioning system (RTK-GPS) buoys, cabled deep ocean-bottom pressure gauges (OBPG), and Deep-ocean Assessment and Reporting of Tsunami (DART) buoys. The purpose of this study is to provide a brief overview of major differences between point-source and finite-fault methodologies on generation and simulation of tsunamis. Tests of the assumptions of uniform and non-uniform slip models designate that the average uniform slip models may be used for the tsunami simulations off-shore, and far from the source region. Nevertheless, the heterogeneities of the slip distribution within the fault plane are substantial for the wave amplitude in the near field which should be investigated further.

Tsunamis of the Past

Geology According to some seismic hazard maps, a large earthquake was not expected to occur offshore of the Tohoku region in Japan. The occurrence of the 2011 Mw 9.0 Tohoku-oki earthquake—one of the largest earthquakes in recorded history—and the resulting devastation after both the earthquake and the subsequent tsunami demonstrated that the model used to assess risk in that region may need serious revision. However, there were some signs that the region had the potential for a very large earthquake. Previous, although uncertain, historical accounts and sedimentological records of a large tsunami point to the occurrence of another large earthquake in 869 CE, often called the Jogan earthquake. Sawai et al. synthesized sedimentary data, including diatom assemblages and radiocarbon dates, of nearly 400 new and previously identified paleotsunami deposits from the Jogan and other historical earthquakes along the coast of Japan. By combining observations of coseismic subsidence in the sediment with tsunami simulation models, the authors estimate that the size of the Jogan earthquake was at least Mw 8.4, and the resultant tsunami reached at least 1.5 km inland. With a recurrence interval of 500 to 800 years, large earthquakes in this region of Japan do not occur frequently but are more likely to occur than predicted by previous hazard models. ![Figure][1] CREDIT: WIKIMEDIA COMMONS Geophys. Res. Lett. 10.1029/2012GL053692 (2012). [1]: pending:yes

TSUNAMI HAZARD AND CASUALTY ESTIMATION IN A COASTAL AREA THAT NEIGHBORS THE INDIAN OCEAN AND SOUTH CHINA SEA

In the Indian Ocean and the South China Sea, many hundreds of thousands of lives have been lost due to tsunami events, and almost half of the lives lost occurred following the 2004 Indian Ocean event. Potential tsunami case scenarios have been simulated in these regions by a number of researchers to calculate the hazard level. The hazard level is based on a variety of conditions, such as the tsunami height, the inundation area, and the arrival time. However, the current assessments of the hazard levels do not focus on the tsunami risk to a coastal population. This study proposes a new method to quantify the risk to the coastal population in the region that includes the Indian Ocean and the South China Sea. The method is simple and combines the use of readily available tsunami data, far-field tsunami simulation models to determine the regional risk and global population data. An earthquake-generated tsunami was simulated, following an earthquake that had a magnitude larger than 8.5 Mwand occurred along a potential subduction zone. The 2004 Indian Ocean event seemed to be a "worst case scenario"; however, it has been estimated that a potential tsunami, occurring in a coastal region with a high population density, could cause significantly greater casualties.

Tsunami simulation of the October 25, 2010, South Pagai Island, Sumatra earthquake

In this study, two kinds of tsunami numerical models based on the shallow water equations were employed to simulate the South Pagai Island, Sumatra earthquake tsunami which occurred in 25 October 2010. The models consist of generation, propagation and arrival times along affected coasts in Mentawai islands. Post event tsunami calculations were performed in order to better represent the event and identify more in detail the affected locations. The numerical models were performed by using nonlinear and dispersive long wave tsunami models (TUNAMI N2 and SWAN) with GEBCO30 and ETOPO2 bathymetry data in a coarse 2′ and 4′ basin scale grid. The simulated waves were particulary high on the South shore of the islands of Mentawai where they reached. This is in agreement with the locations indicated by the survey reports as most affected. The simulated waves were also compared with the available deep ocean pressure sensors and tide gauge records. Results of the numerical simulations except for the Padang2 tide gauge measurement are in reasonable agreement with data of observations. In this regard, numerical simulations are important for the purpose of providing mitigation measures to reduce the potential impacts and risks on local communities in the islands. Therefore, the main purpose of this study was conducted to contribute to reveal the effects of the earthquake in the region by using the tsunami simulation models considering the occurrence of tsunami in the future at the same area. Key words: Mentawai Islands, earthquake source parameters, tsunami, tsunami simulation, bathymetry.

SIMULATION OF FUTURE ANDAMAN TSUNAMI INTO STRAITS OF MALACCA BY TUNA

The Andaman tsunami that occurred on 26 December 2004 has initiated and sustained keen research interest on modeling the characteristics and impacts of tsunami, with particular reference to tsunami wave heights, velocities and travel times. We have developed an in-house tsunami simulation model known as TUNA based upon the shallow water equations SWE for the purpose of simulating these tsunami characteristics. In this paper we present simulated tsunami scenarios along Malaysian coasts in the Straits of Malacca due to a potential earthquake originating in the Andaman Sea. Linear shallow water equations (LSWE) are used in the deep ocean, without the friction and advection terms to reduce computational time. On the other hand, in regions with shallow depth and over the beaches, non-linear shallow water equations (NSWE) and moving boundary are used in TUNA. Simulation results with TUNA indicate satisfactory performance when compared to simulation results from COMCOT and on-site survey results for the 2004 Andaman tsunami. Finally we discuss future enhancement of TUNA to improve its performance and to extend its applications to include ecological and water quality simulations.

Application of Particle Filter to Identification of Tsunami Simulation Model

Data assimilation in geophysics is a method of combining a numerical simulation model and incomplete observation data. A data assimilation problem can be formulated by an estimation using a nonlinear state space model and can be resolved using the particle filter. In this paper, we give a framework for resolving the correction and identification problem of erroneous tsunami simulation models using data assimilation. A numerical experiment is also conducted and its result shows the validity of applying data assimilation and the particle filter to a tsunami simulation model.

The source mechanism and numerical modelling of the 1953 Suva tsunami, Fiji

A study is presented on the cause of the destructive tsunami that struck Suva City in 1953 following a moderate offshore earthquake ( M S 6.75). Alternative earthquake and submarine landslide source mechanisms are modelled using the Geowave tsunami simulation model and compared with observational reports. A simulation using a 60 million cubic metre submarine landslide located at the head of the Suva Canyon, 4 km to the WSW of Suva City reproduces the observed run-up. The simulation shows that high variability in tsunami impact over short coastal distances of Suva are attributable to the complex interplay of wave propagation with the barrier reef system, variable lagoon bathymetry and irregularly shaped coastline. The earthquake tsunami may have been responsible for the observed small “warning” wave, which preceded the destructive tsunami waves initiated by the submarine landslide.

An analysis of 2004 Sumatra earthquake fault plane mechanisms and Indian Ocean tsunami

The 2004 Sumatra earthquake and the associated tsunamis are one of the most devastating natural disasters in the last century. Several fault plane models have been suggested to represent the rupture mechanism of the earthquake. During this tsunami event, two satellites flew over Bay of Bengal and provided measurements for sea surface elevation with accuracy better than 4.2 cm. The satellite data provide an opportunity to further calibrate and validate the fault mechanism and tsunami propagation models as well. Thus, based on the proposed fault plane models, a series of numerical simulations for tsunami generation and propagation in the Bay of Bengal have been carried out. In comparison with the satellite data, the numerical results show that although the length of the entire ruptured zone is up to 1300 km long for this earthquake, the duration of slip and the rupture speed are still relatively short in comparison with the time scale and the propagation speed of tsunami and the impulsive fault plane model simulates reasonably well the tsunamis in the deep ocean.An inverse method is developed to optimize the seafloor displacement on the fault plane based on the measurements of satellite Jason-1. Finally, employing the optimized fault plane model, we demonstrate that the tsunami simulation model can produce results that match very well with the measurements of sea surface level by satellite TOPEX/Poseidon and available tidal gage measurements at Maldives.