Simulation Of Tsunami Propagation Research Articles

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.

Modeling tides and tsunami propagation in the former Gulf of Tartessos, as a tool for Archaeological Science

After the last Holocene sea level rise (about 6900 BP), the Gulf of Tartessos extended over the south-western area of the nowadays Guadalquivir Valley (Spain). With the development of some depositional littoral landforms and the progressive infill, the system evolved towards an inland lagoon. The first political system in the area emerged and collapsed from the fourth to the second millennium BC. Around the first millennium BC the culture of Tartessos flourished in this area under the Phoenician influence, but it vanished by the sixth century BC. The quest of its lost capital, the city of Tartessos, has been one of the most exciting archaeological enterprises in the past century. The former coastline and the bathymetry of the gulf can be reasonably reconstructed from geo-archaeological studies, and it can be used for the numerical modeling of tide and tsunami propagation in this water body. Models, with a spatial resolution of 30 s of arc, are based on the 2D non-linear hydrodynamic equations and have been previously validated under nowadays conditions. Computed tidal elevations and currents can provide some insight on the ancient trades for ship traffic and fisheries. The simulation of tsunami propagation, like the catastrophic one of 1755, allows estimating their potential hazardous effects on ancient coastal cities.

Three‐dimensional tsunami propagation simulations using an unstructured mesh finite element model

AbstractLarge‐scale tsunami propagation simulations from the fault region to the coast are conducted using a three‐dimensional (3‐D) parallel unstructured mesh finite element code (Fluidity‐ICOM). Unlike conventional 2‐D approximation models, our tsunami model solves the full 3‐D incompressible Navier‐Stokes (NS) equations. The model is tested against analytical solutions to simple dispersive wave propagation problems. Comparisons of our 3‐D NS model results with those from linear shallow water and linear dispersive wave models demonstrate that the 3‐D NS model simulates the dispersion of very short wavelength components more accurately than the 2‐D models. This improved accuracy is achieved using only a small number (three to five) of vertical layers in the mesh. The numerical error in the wave velocity compared with the linear wave theory is less than 3% up to kH = 40, where k is the wave number and H is the sea depth. The same 2‐D and 3‐D models are also used to simulate two earthquake‐generated tsunamis off the coast of Japan: the 2004 off Kii peninsula and the 2011 off Tohoku tsunamis. The linear dispersive and NS models showed good agreement in the leading waves but differed especially in their near‐source, short wavelength dispersive wave components. This is consistent with the results from earlier tests, suggesting that the 3‐D NS simulations are more accurate. The computational performance on a parallel computer showed good scalability up to 512 cores. By using a combination of unstructured meshes and high‐performance computers, highly accurate 3‐D tsunami simulations can be conducted in a practical timescale.

Estimation of Tsunami-Inundated Areas in Asahi City, Chiba Prefecture, after the 2011 Tohoku-Oki Earthquake

The 2011 off the Pacific coast of Tohoku-oki earthquake triggered an extremely large tsunami. The authors conducted a field survey in Asahi City, Chiba Prefecture, after the occurrence of the earthquake. Although located farther away from the source region of the earthquake, there was still significant damage in this area. Tsunami-inundated areas in Asahi City were identified from the map developed by disaster relief volunteers and the satellite images captured after the event. Polygons to demonstrate the tsunami-inundated areas were developed in the geographic information system. The authors compared the identified affected areas with the existing tsunami hazard map of Asahi City. The relationship between the tsunami-inundated areas and the locations of seawalls and tide-prevention forests was evaluated. In addition, a numerical simulation of tsunami propagation was performed and the ratio of totally collapsed buildings to the total number of buildings, that is, damage ratio, in terms of the estimated inundation depths was evaluated.

Owen Ridge deep-water submarine landslides: implications for tsunami hazard along the Oman coast

Abstract. The recent discovery of voluminous submarine landslides along the Owen Ridge may represent a source of tsunami hazard for the nearby Oman coast. We assess the severity of this potential hazard by performing numerical simulations of tsunami generation and propagation from the biggest landslide (40 km3 in volume) observed along the Owen Ridge. A finite-difference model, assimilating the landslide to a visco-plastic flow, simulates tsunami generation. Computation results show that Salalah city (190 000 inhabitants) is impacted by 2.5 m-high tsunami waves one hour after sediment failure. Higher wave elevation values (4 m) are reached in the low populated Sawqara Bay over 80 min after slide initiation. Although large submarine failures along remote oceanic ridges are infrequent, this study reveals an underestimated source of tsunami hazard in the Arabian Sea.

Three-dimensional simulation of 2011 East Japan-off Pacific coast earthquake tsunami induced vortex flows in the Oarai port

Kim, K.O., Choi, B.H., Pelinovsky, E. and Jung, K.T., 2013. Three-dimensional simulation of 2011 East Japan-off Pacific coast earthquake tsunami induced vortex flows in the Oarai port.The huge tsunami was generated by the 11 March 2011 off coast of the Pacific side of East Japan, recording a maximum 40 meter run up in Iwate prefecture. The tsunami wave attacked the Oarai port of Ibaraki prefecture within 30 minutes, and created an enormous vortex flow within the harbor. A similar feature was observed in the Imwon port, in the Eastern Korean coast during the 1983 tsunami event in the East (Japan) Sea. A set of simulations have been performed to investigate the generation of the powerful vortex caused by the 2011 tsunami event at the Oarai Port. The application of numerical models has successfully reproduced the formation of the vortex in the center of the port, which can be clearly identified in a photograph taken during the tsunami. The simulation of tsunami generation and propagation at the outer sea is performed with a hydrostatic model and, for the investigation of a more detailed transient pattern of water flows, the model which uses full Reynolds-averaged Navier–Stokes equations is applied. Examination of the Oarai and Imwon vortexes implies that the generation and strength of a vortex due to tsunami wave is strongly related in the size and the shape of port and breakwater layouts. The present work indicates that time-variation the inflow through the mouth of a harbor controls the transient pattern of the vortex.

Evolvement of tsunami waves on the continental shelves with gentle slope in the China Seas

Potential tsunami generated in the Okinawa Trench or the Manila Trench may attack the southeast coast of China. The continental shelves with extremely gentle slope in the China Seas affect the evolvement of tsunami waves. In this paper, we carry out the simulation of tsunami propagation based on the fully nonlinear and highly dispersive Boussinesq model, which could describe the nonlinearity and dispersion of water waves quite well. So the undulation characters could be well presented. In terms of the real topographies of the East China Sea and the South China Sea, we take some typical profiles to simulate the hypothetical tsunamis generated in the Okinawa Trench and the Manila Trench. Different waveforms in the near shore regions are obtained. The N-shape tsunami waves will evolve into long wave trains, undular bores or solitons near the coastal area. The numerical results of the near shore waveform provide essential conditions for the further studies of tsunami runup and inundation.

On sediment extent and runup of tsunami waves

Tsunami sediments play an important role in tsunami hazard assessments. Recent tsunami events and their associated tsunami deposits have produced a wealth of sediment data. Surveys of recent tsunami events observed that maximum inland tsunami inundation exceeds the maximum inland extent of sand deposition. A driving question of tsunami sedimentology is whether the difference between maximum tsunami inundation and inland extent of sand can be employed as a measure of inundation for past events for which only the extent of the sand is known. Attempts to infer the causative flow characteristics from these sediments often suffer from uncertainties in the data and from restrictive assumptions made in inversion models. The latter demonstrates that the interaction between the tsunami flow and the movable bed is not fully understood. In our contribution, we employ numerical simulations of tsunami propagation and inundation with MOST and a simple model for deposition. In our simulations, we vary the onshore slope, the initial amplitude, which can be interpreted as offshore wave amplitude, and the grain size. While the initial amplitude and onshore slope influence the difference between maximum inundation and sand extent, the grain size has little effect. The link between the onshore slope, initial amplitude and the difference between the maximum tsunami inundation and inland sediment extent can be employed as a first-order quantitative tool to estimate tsunami flow characteristics and maximum inundation from tsunami deposits. We anticipate these results will improve tsunami hazard assessments and narrow the gap between field observations and numerical simulations.

Modeling tsunami propagation in the Iberia–Africa plate boundary: Historical events, regional exposure and the case-study of the former Gulf of Tartessos

A numerical model to simulate tsunami propagation in south of Iberia waters has been developed. It is based on the 2D non-linear hydrodynamic equations and allows calculating tsunami run-ups. The model has been validated through the simulation of historical tsunamis. Then it is applied to a risk assessment study to evaluate tsunami flooding along the Spanish and Moroccan coasts. A spectral analysis of tsunami waves has also been carried out. Finally, the model has been applied to simulate tsunami propagation in the former Gulf of Tartessos, where the city of the same name could have been located. The objective consists of evaluating if a large tsunami could have destroyed it, as some historians suggest.

Historical tsunamis and present tsunami hazard in eastern Indonesia and the southern Philippines

Eastern Indonesia and the southern Philippines comprise a huge and seismically highly active region that has received less than the deserved attention in tsunami research compared with the surrounding areas exposed to the major subduction zones. In an effort to redress the balance the tsunami hazard in this region is studied by establishing a tsunami event database which, in combination with seismological and tectonic information from the region, has allowed us to define and justify a number of ‘credible worst‐case’ tsunami scenarios. These scenarios have been used in numerical simulations of tsunami generation and propagation to study maximum water level along potentially affected shorelines. The scenarios have in turn been combined to provide regional tsunami hazard maps. In many cases the simulations indicate that the maximum water level may exceed 10 m locally and even reach above 20 m in the vicinity of the source, which is of the same order as what is forecasted along the Sumatra and Java trenches for comparable return periods. For sections of coastlines close to a source, a tsunami may strike only a few minutes after it is generated, providing little time for warning. Moreover, several of the affected areas are highly populated and are therefore also high risk areas. The combination of high maximum water levels, short warning times, dense populations, and relatively short return periods suggests strongly that the tsunami hazard and risk in these regions are alarmingly high.

DETERMINISTIC STUDY ON THE POTENTIAL LARGE TSUNAMI HAZARD IN TAIWAN

Taught by the lesson from the 2011 Tōhoku earthquake and tsunami, we aim to probe into the potential large-scale trench-typed tsunami threats to Taiwan by means of the deterministic method. In this paper, 18 trench-typed tsunami sources and the 4 fault-typed tsunami sources will be constructed. The detailed construction, including the rupture length and width, the scale of seismic moment, the slip as well as the dip angle, will be elaborated. The tsunami numerical model, COMCOT, will be applied to simulate tsunami propagation, run-up and inundation; multi-nested grids will be used for a complete simulation of the process of a tsunami from the beginning to the inundation. The simulation result shows that tsunami source from the northern segment of the Manila Trench will pose a serious threat to the safety of Taiwan's southwest coast. The tsunami energy from the Yap Trench can be substantially projected onto Taiwan, and threatens the coasts of northern, eastern, southern, as well as south-western Taiwan. The tsunami source from off the coast of Hualien will have a greater influence on the east coast of Taiwan.

일본 태평양 연안의 Tokai, Tonankai 및 Nankai의 3연동지진에 의한 지진해일이 제주도 연안에 미치는 영향

본 연구는 지진해일의 전파과정을 수치모의할 수 있는 비선형수치모델을 구축하고, 이로부터 최근 일본 태평양 연안에서 발생 가능성이 제기되고 있는 리히터 규모 9.0의 Tokai, Tonankai 및 Nankai의 3연동지진으로 인한 지진해일이 제주도 연안에 미치는 영향을 검토하였다. 수치해석에 있어서는 천해역에서의 천수효과를 충분히 재현하기 위해 격자접속기법을 이용하였으며, 2011년에 발생한 동일본지진과 1983년 동해중부지진에 의한 지진해일에 대한 수치계산을 수행하여 수위변동, 전파시간, 침수계산 등에 대한 기존의 계산치 및 관측치와의 비교로부터 본 수치모델의 타당성을 검증하였다. 3연동지진에 대한 수치모의는 지진해일의 영향을 충분히 고려할 수 있도록 지진 발생으로부터 10시간 동안 계산을 수행하였다. 수치모의를 통해 지진해일의 전파과정에서의 수위변동은 해저수심변화, 굴절, 회절, 반사 등의 영향에 의해 크게 좌우되며, 우리나라 제주도 연안에서는 사계항에서 1.6 m의 최대지진해일고가 추정되었다. This study proposed a two-dimensional horizontal numerical model based on the nonlinear shallow water wave equations to simulate tsunami propagation and coastal inundation. We numerically investigated the possible impacts of tsunami caused by the triple interlocked Tokai, Tonankai and Nankai Earthquakes on the Jeju coastal areas, using the proposed model. The simultaneous Tokai, Tonankai and Nankai Earthquakes were created a virtual tsunami model of an M9.0 earthquake. In numerical analysis, a grid nesting method for the local grid refinement in shallow coastal regions was employed to sufficiently reproduce the shoaling effects. The numerical model was carefully validated through comparisons with the data collected during the tsunami events by 2011 East Japan Earthquake and 1983 central East Sea Earthquake (Nihonkai Chubu Earthquake). Tsunami propagation triggered by the combined Tokai, Tonanakai and Nankai, Earthquakes was simulated for 10 hours to sufficiently consider the effects of tsunami in the coastal areas of Jeju Island. The numerical results revealed that water level fluctuation in tsunami propagation is greatly influenced by water-depth change, refraction, diffraction and reflection. In addition, the maximum tsunami height numerically estimated in the coastal areas of Jeju Island was about 1.6 m at Sagye port.

Tsunami run-up associated with co-seismic thrust slip produced by the 2011 Mw 9.0 Off Pacific Coast of Tohoku earthquake, Japan

The 2011 Mw 9.0 Off Pacific Coast of Tohoku (Japan) earthquake generated a violent tsunami and unexpected high tsunami wave that caused great substantial damage and ∼18,940 fatalities along the east–northeast coast of Honshu Island of Japan. Analyses of high-resolution remote sensing imagery data acquired before and after the earthquake, combined with the results of field investigations, reveal that (i) run-up height of the tsunami (i.e., the inland limit of tsunami) was spatially variable, ranging from <3m to ∼35m, and (ii) large run-up heights occurred mainly in the areas between Ishinomaki (∼38.2°N) and Miyako city (∼40.2°N), close to the epicenter of 2011 Mw 9.0 earthquake, and showed a gradual decrease away from this region. Combined with the ground motion direction revealed by GPS and seismic data, the distribution of run-up height is consistent with that of ground displacement (calculated from GPS observations) and that of co-seismic thrusting slip on the source fault plane along the plate boundary (calculated from the seismic inversion). The results of numerical simulation of tsunami propagation show that (i) the distributions of tsunami height along the northeast Honshu coastline are constrained mainly by thrusting slip on the source fault plane; and (ii) the height of tsunami wave in special areas was strongly affected by the sawtooth geometry of the coastline.

Nearshore tsunami amplitudes off Sri Lanka due to probable worst-case seismic scenarios in the Indian Ocean

This paper describes a deterministic assessment of the tsunami hazard to Sri Lanka from all active subduction zones in the Indian Ocean Basin. High resolution numerical simulations of tsunami propagation have been carried out for eight plausible maximum-credible seismic scenarios in Northern Sumatra–Andaman, Southern Sumatra, Arakan and Makran subduction segments. The numerical results have been analyzed to obtain wave arrival times and maximum tsunami amplitudes just off the coastline of Sri Lanka. A sensitivity analysis carried out at the outset indicates that the computed tsunami amplitudes off Sri Lanka are only marginally sensitive to the perturbations in the source parameters. Moreover, the computed values of peak tsunami amplitudes and arrival times corresponding to an event similar to the tsunami in 2004 are in good agreement with the respective field observations. The numerical simulations also suggest that the maximum tsunami amplitudes around the coastline of Sri Lanka corresponding to worst-case scenarios in Southern Sumatra, Arakan and Makran seismic zones are only less than about 20–30% of those due to the same in Northern Sumatra–Andaman segment. This means that an event similar to the 2004 tsunami in the Northern Sumatra–Andaman subduction zone could be considered as the worst-case seismogenic tsunami scenario for any part of the coastline of Sri Lanka. The information presented in this paper would help authorities responsible for evacuation to make a better judgement as to the level of probable maximum tsunami heights in different areas along the coastline of Sri Lanka, and act accordingly, if a large earthquake were to occur in any of the subduction zones in the Indian Ocean Basin.

Outline of the 2011 off the Pacific coast of Tohoku Earthquake (M w 9.0)

The Japan Meteorological Agency (JMA) is the sole authority to issue domestic tsunami warnings/advisories to the public in Japan. JMA issues the tsunami warnings/advisories based on hypocentral parameters such as location, depth and magnitude, and the tsunami-simulation database system which stores more than one hundred thousand cases of previously-conducted tsunami-propagation simulation results. This system enables tsunami warnings/advisories to be issued within about three minutes after events. For the devastating tsunami generated by the 2011 off the Pacific coast of Tohoku Earthquake on March 11, 2011, this system successfully functioned and the first warning was issued at 14:49 (Japan Standard Time), which was about three minutes after the occurrence of the earthquake. JMA also monitors sea-level data observed with 172 tide gauges and 12 GPS buoys (there were 11 at the time of the earthquake, and this increased to 12 in May 2011), and they are used for changing grades and areas of tsunami warnings/advisories. This time JMA raised tsunami-warning grades and widened warning areas seven times, and downgraded or cancelled the warnings/advisories four times. Mainly based on tsunami observations, all tsunami warnings/advisories were cancelled at 17:58 on March 13. This was about 2 days and 3 hours after the tsunami warning was issued.

Modified Scheme for Tsunami Propagation with Variable Water Depths

In this study, a modified dispersion-correction scheme describing tsunami propagation on variable water depths is proposed by introducing additional terms to the previous numerical scheme. The governing equations used in previous tsunami propagation models are slightly modified to consider the effects of a bottom slope. The numerical dispersion of the proposed model replaces the physical dispersion of the governing equations. Then, the modified scheme is employed to simulate tsunami propagation on variable water depths and numerical results are compared with those of the previous tsunami propagation model.

High grid resolution and parallelized tsunami simulation with fully nonlinear Boussinesq equations

Numerical simulation of tsunami propagation in large basin across the ocean demands significantly high computational capability in terms of CPU time and memory allocation. Due to this limitation, the use of sequential codes in a single scientific workstation is possible only for small-scale tsunami problem. To overcome this difficulty, a parallel Boussinesq wave model is developed based on the original FUNWAVE sequential model for efficient simulation of long wave propagation, coastal inundation and runup. The numerical resolution is decomposed into small sub-domains using domain decomposition technique for each processor to perform the calculations. The wave information is exchanged between processors via message passing interface (MPI). We show the effectiveness of this parallel code on distributed- and shared-memory computer clusters in simulating two tsunami events: the 2004 Indian Ocean and the 1999 Vanuatu tsunamis. Communication in the overlapping domains and load balancing in the partitioned domains are considered to ensure the efficiency of this method. It is found that the performance of the parallel model for both large- and small-scale tsunami problems is very satisfactory. Finally, the parallel model is applied to a spatial hierarchical grids methodology for a location-specific numerical simulation. Grid sensitivity and improved simulation results for runups along Phang Nga coastline from Takua Thung to Khao Lak are presented.

Assessment of potential tsunamigenic seismic hazard to Sri Lanka

PurposeThe purpose of this paper is to present an assessment of the potential tsunamigenic seismic hazard to Sri Lanka from all active subduction zones in the Indian Ocean Basin.Design/methodology/approachThe assessment was based on previous studies as well as past seismicity of the subducion zones concerned.FindingsAccordingly, four seismic zones capable of generating teletsunamis that could reach Sri Lanka have been identified, namely, Northern Andaman‐Myanmar, Northern Sumatra‐Andaman and Southern Sumatra in the Sunda trench and Makran in the Northern Arabian Sea. Moreover, plausible worst‐case earthquake scenarios and respective fault parameters for each of these seismic zones have been recommended.Research limitations/implicationsHowever, other potential tsunami sources such as seismic activity in the near‐field, submarine landslides and volcanic eruptions have not been considered.Practical implicationsNumerical simulations of tsunami propagation have been carried out for each of the four scenarios in order to assess the potential impact along the coastline of Sri Lanka. Such information relating to the spatial distribution of the likely tsunami amplitudes and arrival times for Sri Lanka would help authorities responsible for evacuation to make a better judgment as to the level of threat in different areas along the coastline, and act accordingly, if a large earthquake were to occur in any of the subduction zones in the Indian Ocean.Originality/valueIn the absence of comprehensive probabilistic assessments of the tsunami hazard to Sri Lanka, this paper's recommendations would provide the necessary framework for the development of deterministic tsunami hazard maps for the shoreline of Sri Lanka.

Numerical simulation and field survey of inundation due to 2004 Indian Ocean tsunami in Trincomalee, Sri Lanka

This paper outlines the field measurements and numerical modelling carried out to develop a high-resolution tsunami inundation map, as a case study, for the city of Trincomalee on the east coast of Sri Lanka, which was devastated by the 2004 tsunami. We employ the deterministic approach together with numerical simulations based on the probable worst-case scenario to derive the inundation map. Linear and non-linear versions of shallow-water equations have been utilized to simulate tsunami propagation and onshore inundation, respectively. The field data considered in the present paper comprise the extent of inundation, the tsunami heights and the arrival times whilst the model results include the spatial distribution of the flow depth, the peak current speeds and the momentum flux. The computed extent of onshore inundation reproduces the observed overall pattern of inundation in most areas barring the south-eastern part of the city. Further, the model simulations suggest maximum flow depths up to about 2 m in most areas of the city whilst patches of flow depths exceeding 2 m can be seen in a narrow strip along the coastline. The computed current speeds also exceed 3 m/s at some locations adjacent to the shoreline.

Field measurements and numerical simulations of the 2004 tsunami impact on the south coast of Sri Lanka

This paper examines the factors that have contributed to the significant spatial variability of the impact of the December 2004 tsunami in the southern province of Sri Lanka. Documented observations of the evidence left behind by the 2004 tsunami together with numerical simulation of tsunami propagation have been utilized for this purpose. The field data examined in the present analysis comprise the maximum water levels, the horizontal inundation distances and the number of housing and other buildings damaged as a result of the 2004 tsunami whilst the numerical results considered include the distribution of the amplitude of the tsunami. The present model results confirm that source directivity controls the distribution of tsunami amplitudes farther offshore whilst large-scale bathymetric features significantly influence the tsunami propagating over the shelf. Our analyses of field data also show the dominant influence of coastal geomorphology and topography on the extent of tsunami inundation.