scholarly journals The 1755 Lisbon Tsunami at Vila do Bispo Municipality, Portugal

2015 ◽  
Vol 10 (6) ◽  
pp. 1067-1080 ◽  
Author(s):  
Angela Santos ◽  
◽  
Shunichi Koshimura ◽  
Keyword(s):  
Numerical Model ◽  
Historical Data ◽  
Source Area ◽  
Tsunami Hazard ◽  
Tsunami Source ◽  
Historical Event ◽  
Natural Landscape ◽  
Field Surveys ◽  
Tsunami Hazard Assessment ◽  
Gorringe Bank

The numerical model of the 1755 Lisbon Tsunami was conducted at Vila do Bispo municipality. The tsunami source area of this historical event is assumed to be on the Gorringe Bank. Numerical model results of historical data have been validated by a combined analysis of eyewitnesses’ accounts, field surveys, geological records and archeological findings (conducted by previous authors). The coastal area has remained a mostly natural landscape since the 18thcentury, with popular beaches that increase the population potentially exposed to a tsunami, especially one occurring in summer. For these reasons, we use local tsunami hazard assessment as a criterion varying between moderate and critical. Results also show that the 16 low ground areas we surveyed were inundated between 15 and 30 minutes after the earthquake. For this reason, persons should act quickly in future to evacuate areas immediately after an earthquake and to move to higher ground. Results also show that safe, swift evacuation may be difficult in 50% of these areas, endangering special populations such as tourists. Tsunami information boards should therefore be put on beaches and evacuation exercises and drills should be implemented and practiced regularly.

The 1755 Lisbon Tsunami: Tsunami Source Determination and its Validation

2009 ◽  
Vol 4 (1) ◽  
pp. 41-52 ◽  
Author(s):  
Angela Santos ◽  
◽  
Shunichi Koshimura ◽  
Fumihiko Imamura ◽  
Keyword(s):  
North Atlantic Ocean ◽  
Source Area ◽  
Tsunami Source ◽  
The North ◽  
Source Determination ◽  
Historical Tsunami ◽  
Wave Ray ◽  
Lisbon Earthquake ◽  
Gorringe Bank ◽  
Historical Accounts

The Lisbon Earthquake of November 1, 1755, one of the most catastrophic events that has ever occurred in Portugal, Spain, or Morocco, caused severe damage and many casualties. The tsunami generated by this earthquake is well documented in historical accounts, it was reported throughout the North Atlantic Ocean, as it reached not only Portugal, Spain, and Morocco, but also the Madeira and Azores Archipelagos, England, Ireland, and the Caribbean. In spite of the importance of this event, the source of the tsunami remains unknown. In this paper, the authors reevaluate some of the historical tsunami travel times obtained by previous authors. Based on these times, wave ray analysis is used to determine the location of the tsunami source area. These results, combined with turbidites obtained by previous authors at the Tagus and Horseshoe Abyssal Plains, lead to the conclusion that the source of the 1755 Lisbon Tsunami could be located in the area of the Gorringe Bank. Then, a hydrodynamic simulation is carried out with this area presupposed as the source. The numerical model results provide good agreement when compared with both historical and sedimental records. However, in the past, the Gorringe Bank has been dismissed as the source of this tsunami for several reasons. Therefore, these issues are discussed and discredited. As a consequence of all these facts, it can be concluded that the origin of the 1755 Lisbon Earthquake and Tsunami could be located in the area of the Gorringe Bank.

Submarine landslide recurrence and links to seismicity on the Gorringe Bank Seamount, Offshore Portugal

2020 ◽  
Author(s):  
Davide Gamboa ◽  
Rachid Omira ◽  
Pedro Terrinha ◽  
Aldina Piedade
Keyword(s):  
Tsunami Hazard ◽  
Submarine Landslides ◽  
Close Link ◽  
Bathymetric Data ◽  
Tsunami Hazard Assessment ◽  
History Of ◽  
Funded Project ◽  
Gorringe Bank ◽  
Seismic Reflection Profiles ◽  
Northern Segment

<p>Submarine landslides are common features occurring on the flanks of seamounts. Often triggered by earthquakes or volcanic activity, such landslides are potential generators of tsunamis that constitute a dire geohazard for coastal communities. Understanding the recurrence history and geomorphology of seamount-flanking landslides and their link to seismic triggers is crucial for tsunami hazard assessment. This work aims at revealing the recurrence history of the landslides on the Gorringe Bank and their role on regional geohazards. Morphologically, the Gorringe Bank is the largest submarine seamount in Europe, with a length of circa 180 km and a height of 5000 m. It is linked to NW-directed thrusting which led to the exhumation of upper mantle lithologies in this major bathymetric structure. Numerous landslide scars are identified on both its northern and southern flanks, yet there is limited evidence of their presence and morphology on modern bathymetric data. A wealth of 2D seismic reflection profiles from offshore Southwest Portugal is here used to analyse the occurrence, timing and morphology of landslides complexes on the northwestern flank of the Gorringe Bank. A widespread frontal landslide complex of approximate Upper Miocene age is present along the whole flank, likely associated with the main phase of uplift. However, the recurrence of expressive submarine landslides in the Plio-Quarternary sequence is generally focused towards the northern segment of the Gorringe Bank. The geographical correlation between the areas of higher landslide number and clusters of seismicity epicentres suggest a close link between the two. This has direct implications for the assessment of landslide-prone locations on the seamount and to regional tsunami hazard models applicable to the Iberian and Northern African margins.</p><p>This work is supported by the FCT funded project MAGICLAND - MArine Geo-hazards InduCed by underwater LANDslides in the SW Iberian Margin (Ref: PTDC/CTA-GEO/30381/2017),</p>

scholarly journals Deterministic approach for multiple-source tsunami hazard assessment for Sines, Portugal

2015 ◽  
Vol 15 (11) ◽  
pp. 2557-2568 ◽  
Author(s):  
M. Wronna ◽  
R. Omira ◽  
M. A. Baptista
Keyword(s):  
Sea Level ◽  
Wave Height ◽  
Hazard Assessment ◽  
Test Site ◽  
Tsunami Hazard ◽  
Deterministic Approach ◽  
Flow Depth ◽  
Mean Sea Level ◽  
Tsunami Hazard Assessment ◽  
The Impact

Abstract. In this paper, we present a deterministic approach to tsunami hazard assessment for the city and harbour of Sines, Portugal, one of the test sites of project ASTARTE (Assessment, STrategy And Risk Reduction for Tsunamis in Europe). Sines has one of the most important deep-water ports, which has oil-bearing, petrochemical, liquid-bulk, coal, and container terminals. The port and its industrial infrastructures face the ocean southwest towards the main seismogenic sources. This work considers two different seismic zones: the Southwest Iberian Margin and the Gloria Fault. Within these two regions, we selected a total of six scenarios to assess the tsunami impact at the test site. The tsunami simulations are computed using NSWING, a Non-linear Shallow Water model wIth Nested Grids. In this study, the static effect of tides is analysed for three different tidal stages: MLLW (mean lower low water), MSL (mean sea level), and MHHW (mean higher high water). For each scenario, the tsunami hazard is described by maximum values of wave height, flow depth, drawback, maximum inundation area and run-up. Synthetic waveforms are computed at virtual tide gauges at specific locations outside and inside the harbour. The final results describe the impact at the Sines test site considering the single scenarios at mean sea level, the aggregate scenario, and the influence of the tide on the aggregate scenario. The results confirm the composite source of Horseshoe and Marques de Pombal faults as the worst-case scenario, with wave heights of over 10 m, which reach the coast approximately 22 min after the rupture. It dominates the aggregate scenario by about 60 % of the impact area at the test site, considering maximum wave height and maximum flow depth. The HSMPF scenario inundates a total area of 3.5 km2.

Generating Random Earthquake Events for Probabilistic Tsunami Hazard Assessment

2016 ◽  
Vol 173 (12) ◽  
pp. 3671-3692 ◽  
Author(s):  
Randall J. LeVeque ◽  
Knut Waagan ◽  
Frank I. González ◽  
Donsub Rim ◽  
Guang Lin
Keyword(s):  
Hazard Assessment ◽  
Tsunami Hazard ◽  
Tsunami Hazard Assessment ◽  
Probabilistic Tsunami Hazard Assessment

Regional tsunami hazard maps for the Far East coast of the Russian Federation built in the framework of the PTHA methodology

2019 ◽  
pp. 55-72
Author(s):  
Вячеслав Константинович Гусяков ◽  
Владимир Андреевич Кихтенко ◽  
Леонид Борисович Чубаров ◽  
Юрий Иванович Шокин
Keyword(s):  
Russian Federation ◽  
Hazard Assessment ◽  
East Coast ◽  
Far East ◽  
Tsunami Hazard ◽  
Eastern Coast ◽  
The Far East ◽  
Tsunami Hazard Assessment ◽  
The Russian Federation ◽  
Probabilistic Tsunami Hazard Assessment

В работе идет речь о реализации методики вероятностного цунамирайонирования побережья, известной под названием PTHA (Probabilistic Tsunami Hazard Assessment), для создания обзорных карт цунамиопасности дальневосточного побережья России. Обсуждаются методологические основы такого подхода, проблемы построения сейсмотектонических моделей основных цунамигенных зон, численные методики получения расчетных каталогов высот волн на побережье. Приведены примеры обзорных карт для различных повторяемостей, построенных с применением методики PTHA и представленных с помощью созданного веб-приложения WTMap. Упоминаются также некоторые проблемы применения методики PTHA, связанные как с недостаточностью данных наблюдений, так и со сложностью выполнения большого объема сценарного численного моделирования. The article describes the results of the implementation of the PTHA (Probabilistic Tsunami Hazard Assessment) methodology for creating the overview maps of tsunami hazard for the Far East coast of the Russian Federation. Such maps show the characteristics of the catastrophic impact of tsunami waves on the coast and the probability of their exceeding in a given period of time. The methodological basis of the PTHA approach to the assessment of tsunami hazard, the problems of constructing seismotectonic models of the main tsunamigenic zones, mathematical models and algorithms for calculating probability estimates of tsunami danger are discussed. The version of the PTHA methodology outlined in the article is implemented as a “WTmap” Web-application that has an access to the entire observational information related to coastal tsunami zoning and software packages used. The application allows to obtain the estimates of the expected tsunami heights and their recurrence estimates and to map them on specific parts of the Far Eastern coast of the Russian Federation. The obtained estimates can be quickly recalculated when replacing the observational catalogs with more complete and reliable ones, with the addition of new, previously absent events or the revision of their parameters, as well as the results of new scenario calculations. Examples of overview maps for various recurrence intervals, constructed using the PTHA methodology and presented using the “WTMap” application, are given. Some problems of using the PTHA methodology related to the lack of available observational data and to the complexity of performing a large amount of scenario simulations are also discussed.

scholarly journals Multilayer-HySEA model validation for landslide generated tsunamis. Part I Rigid slides

2020 ◽  
Author(s):  
Jorge Macías ◽  
Cipriano Escalante ◽  
Manuel J. Castro
Keyword(s):  
Bottom Topography ◽  
Companion Paper ◽  
Measured Data ◽  
Tsunami Hazard ◽  
Benchmark Problems ◽  
Experiment Data ◽  
The Us ◽  
Tsunami Hazard Assessment ◽  
Model Equations ◽  
Gpu Architectures

Abstract. The present work is devoted to the benchmarking of the Multilayer-HySEA model using laboratory experiment data for landslide generated tsunamis. This first part of the work deals with rigid slides and the second part, in a companion paper, with granular slides. The US National Tsunami Hazard and Mitigation Program (NTHMP) has proposed the experimental data used and established for the NTHMP Landslide Benchmark Workshop, held in January 2017 at Galveston. The first three benchmark problems proposed in this workshop dealt with rigid slides, simulated as a moving bottom topography, that must be imposed as a prescribed boundary condition. These three benchmarks are used here to validate the Multilayer-HySEA model. This new model of the HySEA family consists of an efficient hybrid finite volume/finite difference implementation on GPU architectures of a non-hydrostatic multilayer model. A brief description of model equations, its dispersive properties, and the numerical scheme is included. The benchmarks are described and the numerical results compared against the lab measured data for each of them. The specific aim of the present work is to validate this new code for tsunamis generated by rigid slides. Nevertheless, the overall objective of the current benchmarking effort is to produce a ready-to-use numerical tool for real world landslide generated tsunami hazard assessment. This tool has already been used to reproduce the Port Valdez Alaska 1969 event.

scholarly journals Feature Names and Identity in Zimbabwe

2012 ◽  
Vol 4 (2) ◽  
Author(s):  
Emmanuel Chabata
Keyword(s):  
Historical Event ◽  
Physical Entity ◽  
Place Names ◽  
Natural Landscape ◽  
Physical Features ◽  
The Way

This paper is about feature names in Zimbabwe. It focuses on the role played by place names in defining Zimbabwe, both as a physical entity and as a community of speakers with a remarkable history and a sense of nationhood. The paper thus focuses on two types of place names, that is, those that refer to the natural landscape, such as mountains and rivers, as well as those that refer to man-made features such as roads and streets, hospitals and schools. Regarding names that are bestowed onto the features of the natural landscape, we will look at how some place names vividly describe the outstanding features or characteristics of particular geographical features, that is, the extent to which the names are used as tools in describing the features; the way the eye meets the landscape. We will also look at how some names of physical features are coined in response to the landscape's 'behaviour' or in relation to the link the landscape has with historical event(s). The paper will also look at how the bestowal of commemorative names on Zimbabwean features has been used in concretising the Zimbabwean people's link with the country's history, that is, how Zimbabweans have tried to define themselves as a people through naming some of their popular places after names of the country's heroes and heroines, both living and dead.

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