scholarly journals TSUNAMI HAZARD AND DESIGN OF COASTAL STRUCTURES

1976 ◽  
Vol 1 (15) ◽  
pp. 130
Author(s):  
George Pararas-Carayannis
Keyword(s):  
Tsunami Wave ◽  
Time History ◽  
Tsunami Hazard ◽  
Wave System ◽  
Tsunami Generation ◽  
Coastal Structures ◽  
Tsunami Height ◽  
Tsunami Propagation ◽  
Coastal Site ◽  
Tsunami Waves

Damage of coastal structures by tsunamis results by the direct and indirect action of hydrostatic and dynamic pressures, foundation failures, overtopping and flooding. Reliable assessment of the potential tsunami hazard at a coastal site and adequate engineering design of critical structures require analysis and understanding of all aspects of a tsunami system leading to its terminal behavior. Description of the space-time history of tsunami waves generated by impulsive disturbances require consideration of events and processes in the following regimes: (a) generation; (b) propagation and dispersion; and (c) termination. Processes and events in each regime during the development of a tsunami are under their own unique hydrodynamic constraints but are dependent on what has preceeded. In predicting tsunami wave characteristics at some distance from the generating source, the error structure may be pyramidal. Essential to any method of tsunami prediction at a distant or a nearby coast will be the full consideration and study of tsunami generative mechanisms. If the tsunami generation mechanics cannot be deduced with a reasonable degree of accuracy, it is not likely that the tsunami terminal aspects will be reliably predicted. Prediction of tsunami height at a distant or at a nearby coast requires knowledge of the magnitude and type of ground displacements in the tsunami generating area and of the characteristics of the surface waves resulting from such action. Although all mechanisms involved during tsunami generation are not fully understood, it is possible to obtain a suitable tsunami initiating function through the use of experimental data, historical data, and established empirical relationships, for each type of generating mechanism. Reliable computation of the tsunami propagation effects over and across the ocean can be obtained with proper modeling to provide an adequate description of the tsunami energy flow through the use of physical and numerical studies. Similarly, the terminal aspects and nearshore modification of the tsunami wave system can be approximated to provide the engineering criteria necessary for the assessment of the potential tsunami hazard at a coastal site.

A multi-scenario assessment of the seismogenic tsunami hazard for Bangladesh

2019 ◽  
Vol 11 (2) ◽  
pp. 156-168
Author(s):  
Janaka J. Wijetunge
Keyword(s):  
Subduction Zones ◽  
Submarine Canyon ◽  
Tsunami Hazard ◽  
Seismic Zone ◽  
Tsunami Propagation ◽  
Content Type ◽  
Arrival Times ◽  
Tsunami Waves ◽  
Scenario Assessment ◽  
Seismic Scenarios

Purpose This paper aims to describe a multi-scenario assessment of the seismogenic tsunami hazard for Bangladesh from active subduction zones in the Indian Ocean region. Two segments of the Sunda arc, namely, Andaman and Arakan, appear to pose a tsunamigenic seismic threat to Bangladesh. Design/methodology/approach High-resolution numerical simulations of tsunami propagation toward the coast of Bangladesh have been carried out for eight plausible seismic scenarios in Andaman and Arakan subduction zones. The numerical results have been analyzed to obtain the spatial variation of the maximum tsunami amplitudes as well as tsunami arrival times for the entire coastline of Bangladesh. Findings The results suggest that the tsunami heights are amplified on either side of the axis of the submarine canyon which approaches the nearshore sea off Barisal in the seaboard off Sundarban–Barisal–Sandwip. Moreover, the computed tsunami amplitudes are comparatively higher north of the latitude 21.5o in the Teknaf–Chittagong coastline. The calculated arrival times indicate that the tsunami waves reach the western half of the Sundarban–Barisal–Sandwip coastline sooner, while shallow water off the eastern half results in a longer arrival time for that part of the coastline, in the event of an earthquake in the Andaman seismic zone. On the other hand, most parts of the Chittagong–Teknaf coastline would receive tsunami waves almost immediately after an earthquake in the northern segment of the Arakan seismic zone. Originality/value The present assessment includes probabilistic measures of the tsunami hazard by incorporating several probable seismic scenarios corresponding to recurrence intervals ranging from 25 years to over 1,000 years.

scholarly journals THE EXISTENCE OF COASTAL FOREST, ITS IMPLICATION FOR TSUNAMI HAZARD PROTECTION, A CASE STUDY: IN CILACAP-CENTRAL JAVA, INDONESIA

2016 ◽  
Vol 30 (1) ◽  
pp. 23 ◽  
Author(s):  
Yudhicara Yudhicara
Keyword(s):  
Cocos Nucifera ◽  
Tsunami Hazard ◽  
Coastal Protection ◽  
Casuarina Equisetifolia ◽  
Coastal Forest ◽  
Southern Coast ◽  
Coastal Forests ◽  
Tsunami Height ◽  
Tsunami Waves ◽  
Hazard Potential

The southern coast of Java which is facing to the Indian Ocean has many of natural hazard potential come from the sea. Since 2006 tsunami impacted the southern coast of Java, and caused severely damage especially along the coast of Cilacap (1-7,7 m run up height). People commit to do greening the beach by planting suitable plants such as a Casuarina equisetifolia, Terminalia catappa, and Cocos nucifera. This paper discusses the existence of coastal forests in Cilacap coastal area, their potential ability as a coastal protection from the tsunami wave which cover the density, diameter, height, age, and other parameters that affects the coastal defence against tsunami waves. Some experiences of tsunamis that have occurred, indicating that the above parameters linked to the ability of vegetation to act as a natural barrier against tsunamis. In the case of sandy beaches, such as in Cilacap, Pandanus odorarissimus has more effectiveness than other trees due to its hanging roots that can withstand the tsunami height less than 5 m, able to withstand debris and can withstand the scouring effects of tsunami waves, while Casuarina equisetifolia along Cilacap beaches more dominant than other trees, so it is recommended to increase the diversity of plants as well as increase the density and tree placement setting. By field measurement in order to get parameter applied to some graphs, Cilacap coastal forest does not enough capability for tsunami barrier reflected to the tsunami height experience in this region. Ages could be the important parameter in order to have bigger diameter trunk, higher trees height, and high resistance capacity againts tsunami hazard potential. Compare to Kupang, East Nusa Tenggara, Cilacap coastal forest still young and need some more years to make trees ready act as tsunami reduction. Keywords: Cilacap coastal forest, Kupang, tsunami, vegetation parameters. Pantai Selatan Jawa yang berhadapan dengan Samudera Hindia, memiliki banyak potensi mengalami bahaya yang datang dari lautan. Selama tahun 2006, Tsunami telah menimpa sebagian pantai selatan Jawa dan menyebabkan banyak kerusakan parah terutama di sepanjang Pantai Cilacap (tinggi gelombang 1-7,7 m). Masyarakat melakukan penghijauan pantai dengan menanam sejumlah pohon yang sesuai dengan kondisi pantai, seperti pohon cemara pantai (Casuarina equisetifolia), ketapang (Terminalia cattapa) dan kelapa (Cocos nucifera). Tulisan ini membahas penyebaran hutan pantai di wilayah pantai Cilacap, kemampuan dan potensi hutan tersebut sebagai pelindung alami pantai dari bahaya gelombang tsunami, yang terdiri dari kerapatannya, diameter, tingginya, umur, dan parameter lainnya yang mempengaruhi daya tahan pantai terhadap gelombang tsunami. Beberapa pengalaman mengenai kejadian yang telah terjadi, memperlihatkan bahwa parameter tersebut di atas mempengaruhi kemampuan tanaman sebagai penahan alamiah terhadap tsunami. Untuk kondisi pantai berpasir seperti Cilacap, tanaman pandan pantai lebih efektif dibandingkan dengan tanaman lainnya, dikarenakan akarnya yang dapat menahan tinggi gelombang kurang dari 5 m, selain itu akar tersebut dapat menahan material dan erosi vertikal gelombang tsunami, sementara di sepanjang pantai Cilacap, tanaman cemara pantai (Casuarina equisetifolia) lebih dominan dibandingkan tanaman lainnya. Kondisi ini dapat direkomendasikan untuk tetap dipertahankan bahkan ditambah jumlahnya. Di lapangan dilakukan pengukuran parameter tanaman pantai dan hasilnya diplot dalam bentuk grafik dan diaplikasikan dalam grafik yang dibuat berdasarkan hasil penelitian terhadap tsunami di beberapa tempat di dunia terutama di Jepang. Berdasarkan tinggi gelombang maksimum yang pernah terjadi di daerah ini (7,7 m), terlihat bahwa hutan pantai Cilacap belum cukup mampu bertindak sebagai penahan gelombang tsunami. Umur merupakan parameter penting agar pohon memiliki diameter yang besar, pohon yang cukup tinggi dan daya tahan terhadap potensi bahaya tsunami. Dibandingkan dengan hutan pantai di Kupang, Nusa Tenggara Timur, hutan pantai di Cilacap relatif masih muda dan membutuhkan beberapa tahun lagi untuk dapat memperkecil resiko yang ditimbulkan oleh bahaya tsunami. Kata kunci: Hutan pantai Cilacap, Kupang, tsunami dan parameter vegetasi.

scholarly journals Performance of coastal sea-defense infrastructure at El Jadida (Morocco) against tsunami threat: lessons learned from the Japanese 11 March 2011 tsunami

2013 ◽  
Vol 13 (7) ◽  
pp. 1779-1794 ◽  
Author(s):  
R. Omira ◽  
M. A. Baptista ◽  
F. Leone ◽  
L. Matias ◽  
S. Mellas ◽  
...  
Keyword(s):  
Tsunami Wave ◽  
Atlantic Coast ◽  
Digital Terrain Model ◽  
Lessons Learned ◽  
Tsunami Propagation ◽  
Tsunami Waves ◽  
Earthquake Scenarios ◽  
Near Shore ◽  
Wave Conditions ◽  
El Jadida

Abstract. This paper seeks to investigate the effectiveness of sea-defense structures in preventing/reducing the tsunami overtopping as well as evaluating the resulting tsunami impact at El Jadida, Morocco. Different tsunami wave conditions are generated by considering various earthquake scenarios of magnitudes ranging from Mw = 8.0 to Mw = 8.6. These scenarios represent the main active earthquake faults in the SW Iberia margin and are consistent with two past events that generated tsunamis along the Atlantic coast of Morocco. The behaviour of incident tsunami waves when interacting with coastal infrastructures is analysed on the basis of numerical simulations of near-shore tsunami waves' propagation. Tsunami impact at the affected site is assessed through computing inundation and current velocity using a high-resolution digital terrain model that incorporates bathymetric, topographic and coastal structures data. Results, in terms of near-shore tsunami propagation snapshots, waves' interaction with coastal barriers, and spatial distributions of flow depths and speeds, are presented and discussed in light of what was observed during the 2011 Tohoku-oki tsunami. Predicted results show different levels of impact that different tsunami wave conditions could generate in the region. Existing coastal barriers around the El Jadida harbour succeeded in reflecting relatively small waves generated by some scenarios, but failed in preventing the overtopping caused by waves from others. Considering the scenario highly impacting the El Jadida coast, significant inundations are computed at the sandy beach and unprotected areas. The modelled dramatic tsunami impact in the region shows the need for additional tsunami standards not only for sea-defense structures but also for the coastal dwellings and houses to provide potential in-place evacuation.

scholarly journals Estimates of Amplitude Characteristics of Tsunami Wave Run-Up in Various Areas of the Black Sea Coast

2021 ◽  
Author(s):  
A. Yu. Belokon ◽  
Keyword(s):  
Wave Propagation ◽  
Sea Level ◽  
Black Sea ◽  
Tsunami Wave ◽  
Computational Modelling ◽  
Wave Model ◽  
The Black Sea ◽  
Tsunami Propagation ◽  
Tsunami Waves ◽  
Run Up

This paper is devoted to computational modelling of tsunami wave propagation and runup to the shore for some points on the Russian, Turkish, Bulgarian and Ukrainian coasts of the Black Sea. The nonlinear long wave model was used to solve the problem of wave propagation from hydrodynamic tsunami sources, which can constitute the greatest potential danger for the studied coast areas. The hydrodynamic sources were set in the form of an elliptical elevation, the parameters of which were chosen according to the sea level response to an underwater earthquake of magnitude 7. All the sources were located in seismically active areas, where tsunamigenic earthquakes had already occurred, along the 1500 m isobath. Near each of the studied points in the area above 300 m depths, we calculated marigrams, i.e. time-series of sea level fluctuations caused by the passage of waves. Then, a one-dimensional problem of tsunami propagation and run-up on the coast was solved for each of the points under study, where the obtained marigrams were used as boundary conditions. Peculiarities of tsunami wave propagation have been shown depending on the bottom and land relief in the studied areas of the Black Sea. Estimates have been obtained of the sea level maximum rise and fall during surge and subsequent coastal drainage for the characteristic scales of relief irregularity at different points. For possible tsunamigenic earthquakes, the largest splashes may occur in the region of Yalta (2.15 m), Cide (1.9 m), Sevastopol (1.4 m), and Anapa (1.4 m). Tsunami propagation in the Feodosiya and Varna coastal areas is qualitatively similar, with maximum wave heights of 0.64 m and 0.46 m, respectively. The coastlines of Evpatoriya (0.33 m) and Odessa (0.26 m) are least affected by tsunami waves due to the extended shelf.

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

2013 ◽  
Vol 13 (2) ◽  
pp. 417-424 ◽  
Author(s):  
M. Rodriguez ◽  
N. Chamot-Rooke ◽  
H. Hébert ◽  
M. Fournier ◽  
P. Huchon
Keyword(s):  
Finite Difference ◽  
Arabian Sea ◽  
Tsunami Hazard ◽  
Potential Hazard ◽  
Submarine Landslides ◽  
Tsunami Generation ◽  
Difference Model ◽  
Tsunami Waves ◽  
Wave Elevation ◽  
Sediment Failure

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.

scholarly journals Tsunami hazard assessment in the southern Colombian Pacific Basin and a proposal to regenerate a previous barrier island as protection

2013 ◽  
Vol 1 (2) ◽  
pp. 1173-1212
Author(s):  
L. J. Otero ◽  
J. C. Restrepo ◽  
M. Gonzalez
Keyword(s):  
Barrier Island ◽  
Protective Role ◽  
Focal Mechanisms ◽  
Tsunami Hazard ◽  
Tsunami Generation ◽  
Potential Generation ◽  
Tsunami Waves ◽  
Tsunami Hazard Assessment ◽  
Morphological Modification ◽  
The City

Abstract. In this study, the tsunami hazard posed to 120 000 inhabitants of Tumaco (Colombia) is assessed, and an evaluation and analysis of regenerating the previous El Guano Island for tsunami protection is conducted. El Guano Island was a sandy barrier island in front of the city of Tumaco until its disappearance during the tsunami of 1979; the island is believed to have played a protective role, substantially reducing the scale of the disaster. The analysis is conducted by identifying seismotectonic parameters and focal mechanisms of tsunami generation in the area, determining seven potential generation sources, applying a numerical model for tsunami generation and propagation, and evaluating the effect of tsunamis on Tumaco. The results show that in the current situation, this area is vulnerable to impact and flooding by tsunamis originating nearby. El Guano Island was found to markedly reduce flood levels and the energy flux of tsunami waves in Tumaco during the 1979 tsunami. To reduce the risk of flooding due to tsunamis, the regeneration and morphological modification of El Guano Island would help to protect Tumaco.

scholarly journals Tsunami hazard assessment in the southern Colombian Pacific basin and a proposal to regenerate a previous barrier island as protection

2014 ◽  
Vol 14 (5) ◽  
pp. 1155-1168 ◽  
Author(s):  
L. J. Otero ◽  
J. C. Restrepo ◽  
M. Gonzalez
Keyword(s):  
Barrier Island ◽  
Protective Role ◽  
Focal Mechanisms ◽  
Tsunami Hazard ◽  
Tsunami Generation ◽  
Potential Generation ◽  
Tsunami Waves ◽  
Tsunami Hazard Assessment ◽  
Morphological Modification ◽  
The City

Abstract. In this study, the tsunami hazard posed to 120 000 inhabitants of Tumaco (Colombia) is assessed, and an evaluation and analysis of regenerating the previous El Guano Island for tsunami protection is conducted. El Guano Island was a sandy barrier island in front of the city of Tumaco until its disappearance during the tsunami of 1979; the island is believed to have played a protective role, substantially reducing the scale of the disaster. The analysis is conducted by identifying seismotectonic parameters and focal mechanisms of tsunami generation in the area, determining seven potential generation sources, applying a numerical model for tsunami generation and propagation, and evaluating the effect of tsunamis on Tumaco. The results show that in the current situation, this area is vulnerable to impact and flooding by tsunamis originating nearby. El Guano Island was found to markedly reduce flood levels and the energy flux of tsunami waves in Tumaco during the 1979 tsunami. By reducing the risk of flooding due to tsunamis, the regeneration and morphological modification of El Guano Island would help to protect Tumaco.

Seismically Derived Ground Tilts Related to the 2010 Chilean Tsunami

2021 ◽  
Author(s):  
Jui-Chun Freya Chen ◽  
Wu-Cheng Chi ◽  
Chu-Fang Yang
Keyword(s):  
Deep Ocean ◽  
Propagation Model ◽  
Ocean Bottom ◽  
Ocean Bottom Seismometer ◽  
Tsunami Propagation ◽  
Ground Tilt ◽  
Tsunami Waves ◽  
The Pacific ◽  
Seismic Networks ◽  
Back Azimuth

Abstract Developing new ways to observe tsunami contributes to tsunami research. Tidal and deep-ocean gauges are typically used for coastal and offshore observations. Recently, tsunami-induced ground tilts offer a new possibility. The ground tilt signal accompanied by 2010 Mw 8.8 Chilean earthquake were observed at a tiltmeter network in Japan. However, tiltmeter stations are usually not as widely installed as broadband seismometers in other countries. Here, we studied broadband seismic records from Japan’s F-net and found ground tilt signals consistent with previously published tiltmeter dataset for this particular tsunamic event. Similar waveforms can also be found in broadband seismic networks in other countries, such as Taiwan, as well as an ocean-bottom seismometer. We documented a consistent time sequence of evolving back-azimuth directions of the tsunami waves at different stages of tsunami propagation through beamforming-frequency–wavenumber analysis and particle-motion analysis; the outcomes are consistent with the tsunami propagation model provided by the Pacific Tsunami Warning Center. These results shown that dense broadband seismic networks can provide a useful complementary dataset, in addition to tiltmeter arrays and other networks, to study or even monitor tsunami propagation using arrayed methods.

scholarly journals Tsunami wave propagation by voronoi diagram

2018 ◽  
Vol 7 (3) ◽  
pp. 1233
Author(s):  
V Yuvaraj ◽  
S Rajasekaran ◽  
D Nagarajan
Keyword(s):  
Wave Propagation ◽  
Voronoi Diagram ◽  
Tsunami Wave ◽  
Fast Marching Method ◽  
Coastal Regions ◽  
Fast Marching ◽  
Tsunami Waves ◽  
The Finite Difference Method ◽  
Run Up ◽  
Marching Method

Cellular automata is the model applied in very complicated situations and complex problems. It involves the Introduction of voronoi diagram in tsunami wave propagation with the help of a fast-marching method to find the spread of the tsunami waves in the coastal regions. In this study we have modelled and predicted the tsunami wave propagation using the finite difference method. This analytical method gives the horizontal and vertical layers of the wave run up and enables the calculation of reaching time.  

scholarly journals TSUNAMI PHASE SPEED REDUCTION DUE TO WATER COMPRESSIBILTY

2018 ◽  
pp. 9
Author(s):  
Ali Abdolali ◽  
James T. Kirby
Keyword(s):  
Arrival Time ◽  
Phase Speed ◽  
Propagation Speed ◽  
Frequency Dispersion ◽  
Wave Theory ◽  
Polar Coordinates ◽  
Ocean Bottom ◽  
Tsunami Propagation ◽  
Boussinesq Model ◽  
Tsunami Waves

Most existing tsunami propagation models consider the ocean to be an incompressible, homogenous medium. Recently, it has been shown that a number of physical features can slow the propagation speed of tsunami waves, including wave frequency dispersion, ocean bottom elasticity, water compressibility and thermal or salinity stratification. These physical effects are secondary to the leading order, shallow water or long wave behavior, but still play a quantifiable role in tsunami arrival time, especially at far distant locations. In this work, we have performed analytical and numerical investigations and have shown that consideration of those effects can actually improve the prediction of arrival time at distant stations, compared to incompressible forms of wave equations. We derive a modified Mild Slope Equation for Weakly Compressible fluid following the method proposed by Sammarco et al. (2013) and Abdolali et al. (2015) using linearized wave theory, and then describe comparable extensions to the Boussinesq model of Kirby et al. (2013). Both models account for water compressibility and compression of static water column to simulate tsunami waves. The mild slope model is formulated in plane Cartesian coordinates and is thus limited to medium propagation distances, while the Boussinesq model is formulated in spherical polar coordinates and is suitable for ocean scale simulations.

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