O grande Sismo e Tsunami de 1755 em Portugal (M 8.7/9.0)

Tópico em 'Sismologia e Vulcanismo' iniciado por Vince 5 Nov 2009 às 20:04.

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    O grande Sismo e Tsunami de 1755 em Portugal


    http://aeiou.expresso.pt/o-misterio-do-epicentro=f553562




     
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    #3 AnDré, 18 Nov 2009 às 11:01
    Editado por um moderador: 21 Set 2014 às 03:58
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    O Tsunami

    Traduzido daqui: http://nisee.berkeley.edu/lisbon/



    http://www.ngdc.noaa.gov/hazard/tsu_travel_time_events.shtml

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    Literatura e muitos links


    1755 Lisbon earthquake
    The 1755 Lisbon earthquake, also known as the Great Lisbon Earthquake, was a megathrust earthquake that took place on Saturday 1 November 1755, at around 9:40 in the morning.[1] The earthquake was followed by fires and a tsunami, which caused near-total destruction of Lisbon in the Kingdom of Portugal, and adjoining areas. Seismologists today estimate the Lisbon earthquake had a magnitude in the range 8.5–9.0 on the moment magnitude scale,[2] with an epicenter in the Atlantic Ocean about 200 km (120 mi) west-southwest of Cape St. Vincent. Estimates place the death toll in Lisbon alone between 10,000 and 100,000 people,[3] making it one of the deadliest earthquakes in history.
    The earthquake accentuated political tensions in the Kingdom of Portugal and profoundly disrupted the country's eighteenth-century colonial ambitions. The event was widely discussed and dwelt upon by European Enlightenment philosophers, and inspired major developments in theodicy and in the philosophy of the sublime. As the first earthquake studied scientifically for its effects over a large area, it led to the birth of modern seismology and earthquake engineering.
    http://en.wikipedia.org/wiki/1755_Lisbon_earthquake

    New study of the 1755 earthquake source based on multi-channel
    seismic survey data and tsunami modeling

    Abstract. In the last years, large effort has been done to carry
    out multi-channel seismic reflection surveys (MCS) in SW
    Iberia to locate the active tectonic structures that could be related
    to the generation of the 1755 Lisbon earthquake and the
    tsunami. The outcome of these researches led to the identification
    of a large, compressive tectonic structure, named
    Marquˆes de Pombal thrust that, alone can account for only
    half the seismic energy released by the 1755 event. However,
    these investigations have shown the presence of additional
    tectonic structures active along the continental margin of SW
    Iberia that are here evaluated to model the tsunami waves observed
    along the coasts of Iberia, Morocco and Central Atlantic.
    In this paper we present a new reappraisal of the 1755
    source, proposing a possible composite source, including the
    Marquˆes de Pombal thrust fault and the Guadalquivir Bank.
    The test of the source is achieved through numerical modelling
    of the tsunami all over the North Atlantic area. The
    results presented now incorporate data from the geophysical
    cruises and the historical observation along the European
    coasts and also from the Western Indies. The results of this
    study will, hopefully, improve the seismic risk assessment
    and evaluation in the Portuguese territory, Spain, Morocco
    and Central/North Atlantic.
    http://www.nat-hazards-earth-syst-sci.net/3/333/2003/nhess-3-333-2003.pdf


    The 1755 earthquake in the Algarve (South of Portugal):
    what would happen nowadays?

    Abstract. The 1755 Lisbon earthquake, which reached a
    magnitude of 8.5, remains the most powerful and destructive
    to hit Europe so far. Within minutes, many lives were lost,
    populations displaced, livelihoods, homes and infrastructures
    were destroyed. Although frequently associated to the city
    of Lisbon, one of the most important European cities at the
    time, this earthquake caused similar damage and casualties,
    if not greater, in the southwest of the Algarve, where the seismic
    intensity was estimated at IX-X Mercalli Intensity Scale.
    Some time later a tsunami increased the number of victims
    and the amount of damage. In some locations the tsunami
    caused greater destruction than the earthquake itself. The
    tsunami hit both coasts of the North Atlantic; however, the
    more destructive damage occurred in the Portuguese coast,
    south from Lisbon, in the Gulf of Cadiz and in the Moroccan
    coast. The downtown of Lisbon was flooded by waves
    that reached a height of 6 m. The water flooded an area with
    an extension of around 250m from the coast. In the Southwest
    part of Algarve the waves reached a height between 10
    and 15m and the flooded area was much larger. Through the
    analysis of recent research works on the assessment of the
    1755 tsunami parameters and the interpretation of the more
    reliable historical documents, it is our intention to analyse
    the destructive power of the tsunami in the Algarve and delimit
    the flooded area. Using simple techniques of simulation
    it is our intention to assess the impacts nowadays of the occurrence
    of a tsunami similar to the one that hit the Algarve
    in 1755, which would probably affect a greater number of
    people, buildings and infrastructures. This assessment is an
    important instrument not only in terms of disaster preparedness
    but also for the integration of risk mitigation measures
    in land use planning.
    http://www.adv-geosci.net/14/59/2008/adgeo-14-59-2008.pdf

    Europe Earthquake
    Historical earthquakes, such as the devastating 1356 Basel and 1755 Lisbon
    events, highlight the potential earthquake risk in Europe. Relative to other perils,
    earthquake losses can be as important, or exceed, those from wind or flood at long
    return periods. The RMS® Europe Earthquake suite of models enables clients to
    assess earthquake risk for 14 countries across Europe, providing a high-resolution
    capability to price and underwrite policies and manage portfolio aggregations.
    http://www.rms.com/publications/Europe_Earthquake.pdf

    The 1531 Lisbon earthquake
    In January 1531, the Tagus River Estuary was hit by a strong earthquake, the intensity of which in Lisbon was, according to relevant authors, greater than that of the 1755 earthquake. It was cited by most of the European annalists of the time and was responsible for the destruction of structures, the loss of lives, and enormous panic, thus making it one of the most disastrous earthquakes in the history of Portugal. If we give credit to the detailed descriptions, the maximum intensity was probably X MSK. According to our study, the seismic event was probably caused by the Lower Tagus fault zone (LTFZ). A critical review of reports from the time has allowed us to discredit the claims of the earthquake's effects quite far away from the epicenter. Thanks to this the magnitude remains within moderate limits. On the other hand, the study of the earthquake's effects outside Portugal and the consideration of geological factors have allowed us to produce a reliable isoseismal map. Study of this historical earthquake may greatly influence the design of structures in the rapidly developing area of the Tagus estuary.
    http://bssa.geoscienceworld.org/cgi/content/abstract/88/2/319

    Destruction of Atlantis by a great earthquake and tsunami? A
    geological analysis of the Spartel Bank hypothesis

    Numerous geographical similarities exist between Plato’s descriptions of Atlantis and a
    paleoisland (Spartel) in the western Straits of Gibraltar. The dialogues recount a catastrophic
    event that submerged the island ca. 11.6 ka in a single day and night, due to
    violent earthquakes and floods. This sudden destruction is consistent with a great earthquake
    (M . 8.5) and tsunami, as in the Gulf of Cadiz region in 1755 when tsunami runup
    heights reached 10 m. Great earthquakes (M 8–9) and tsunamis occur in the Gulf of
    Cadiz with a repeat time of 1.5–2 k.y., according to the sedimentary record. An unusually
    thick turbidite dated as ca. 12 ka may coincide with the destructive event in Plato’s account.
    The detailed morphology of Spartel paleoisland, as determined from recently acquired
    high-resolution bathymetric data, is reported here. The viability of human habitation
    on this paleoisland ca. 11.6 ka is discussed on the basis of a new bathymetric map.
    http://flotte.ifremer.fr/flotte/content/download/4405/103225/file/TV-GIB-publication.pdf



    WHY THE ATLANTIC GENERALLY CANNOT GENERATE TRANSOCEANIC TSUNAMIS?
    Even though, for administrative purposes, it may be convenient to have a global tsunami warning
    system, this is not feasible for scientific and also socio-economic reasons. The Indian Ocean is connected
    to the Pacific and Atlantic Oceans in the south through the Southern Ocean, and is not connected to the
    Arctic Ocean. The Arctic Ocean is connected to the Pacific and Atlantic Oceans in the north. Because of
    very low population density around it, at present, there is no priority for an Arctic Ocean tsunami warning
    system. For the Pacific Ocean, the tsunami warning system is in existence since 1948. Until now the
    Atlantic and Indian Oceans have no tsunami warning systems because tsunami events are rare in these
    two oceans, as compared to the Pacific Ocean.
    For convenience, we will define the following three terms. First, a global tsunami is one which not
    only propagates throughout the ocean in which it was generated, but also into at least two of the three
    other oceans, albeit with small amplitudes. Second, a trans-oceanic tsunami is one that propagates
    throughout the ocean in which it is generated and could cause loss of life and damage even far away from
    the epicentral area. Third, an ocean-wide tsunami is one which propagates throughout the ocean in which
    it is generated, but the loss of life and damage are mostly confined to the epicentral area.
    There are several major differences among the three oceans with reference to tsunamis. The Pacific
    Ocean generates major global and trans-oceanic tsunamis, as occurred, for example on the 1st of April
    1946 (Aleutian tsunami), on the 22nd of May 1960 (Chilean tsunami) and on the 28th of March 1964
    (Alaska tsunami). Even though tsunamis are much less frequent in the Indian Ocean, it is capable of
    generating global and trans-oceanic tsunamis, such as for example the ones that occurred on the 27th of
    August 1883 (tsunami from the eruption of the volcano Krakatoa) and on the 26th of December 2004.
    However, the Atlantic Ocean does not appear to be capable of generating global tsunamis, generally
    speaking.
    There are several well-documented tsunamis in the Atlantic Ocean in historical times. We
    numerically modelled several of these tsunamis, as will be outlined with some details in the following
    sections. The numerical simulations of all these tsunami events have one thing in common. The Atlantic
    Ocean tsunamis generally do not propagate very far with large amplitudes, which is in contrast to the
    Pacific and Indian Oceans, where the tsunamis travel over trans-oceanic distances, and seem to suffer less
    dissipation. The reason for this could be that the fault zones in the Atlantic are smaller than those in the
    Pacific and Indian Oceans. Pacific Ocean, being large in extent, exhibits somewhat different tsunami characteristics from the Indian Ocean, which is much smaller. Reflected waves from distant boundaries
    do not contribute significantly to the total water levels associated with tsunami waves in the Pacific
    Ocean. On the other hand, in the Indian Ocean, one has to include boundary reflections to determine the
    tsunami heights. In the Atlantic Ocean, since most tsunamis occur close to the boundaries, the question of boundary reflections does not arise.
    http://home.iitk.ac.in/~vinaykg/Iset_42_tn3.pdf


    The impact of eighteenth century earthquakes on the Algarve region, southern Portugal
    In the eighteenth century the Algarve was affected by two large and destructive earthquakes. The first occurred in 1722, had an estimated magnitude of between 6.5 and 7.8 Mw and severely affected the coastal zone of the central Algarve. Thirty three years later in 1755 the ‘Lisbon earthquake’ (magnitude c. 8.5 Mw) killed around 12 000 people in Portugal, of whom just over 1000 lived in the Algarve. With an estimated cost of between 32 and 48% of Portugal's gross national product, in financial terms it is the greatest natural disaster to have affected western Europe and its effects on the Algarve, the region closest to the epicentre, were devastating. Using data collected in the field together with archival materials the authors discuss: the economic and social impacts of these two eighteenth century earthquakes and their associated tsunamis on the Algarve; and recovery of the region in the years that followed. Today the Algarve is a major European tourist destination with a resident population of c.430 000, a figure which almost doubles at the height of the tourist season. The 1722 and 1755 earthquakes were not isolated events, but part of a long and destructive seismic history, and today the region is highly exposed to the effects of future earthquakes and tsunamis. The paper concludes with a discussion of current attempts being made by the Portuguese authorities to reduce hazard exposure by means of building codes, the production of hazard maps and emergency plans. In these plans a 1755 type event is viewed as a worst-case scenario, although because of its epicentral location near to the economic heart of the region and in spite of its smaller size, a 1722 type event would be far more destructive.
    http://onlinelibrary.wiley.com/doi/10.1111/j.1475-4959.2010.00367.x/abstract

    Simulations of strong ground motion in SW Iberia for the 1969
    February 28 (Ms = 8.0) and the 1755 November 1 (M ∼ 8.5)
    earthquakes – II. Strong ground motion simulations

    This is the second paper of a series of two concerning strong ground motion in SW Iberia due
    to earthquakes originating from the adjacent Atlantic area. The aim of this paper is to use the
    velocity model that was proposed and validated in the companion paper for seismic intensity
    modelling of the 1969 (Ms = 8.0) and 1755 (M = 8.5–8.7) earthquakes.
    First, we propose a regression to convert simulated values of Peak Ground Velocity (PGV)
    into Modified Mercalli Intensity (MMI) in SW Iberia, and using this regression, we build
    synthetic isoseismal maps for a large (Ms = 8.0) earthquake that occurred in 1969. Based
    on information on the seismic source provided by various authors, we show that the velocity
    model effectively reproduces macroseismic observations in the whole region.We also confirm
    that seismic intensity distribution is very sensitive to a small number of source parameters:
    rupture directivity, fault strike and fault dimensions. Then, we extrapolate the method to the
    case of the great (M = 8.5–8.7) 1755 earthquake, for a series of hypotheses recently proposed
    by three authors about the location of the epicentral region. The model involving a subductionrelated
    rupture in the Gulf of C´adiz results in excessive ground motion in northern Morocco,
    suggesting that the source of the 1755 earthquake should be located further west. A rupture
    along thewestern coast of Portugal, compatible with an activation of the passivewestern Iberian
    margin, would imply a relatively low average slip, which, alone, would could not account for
    the large tsunami observed in the whole northern Atlantic ocean. A seismic source located
    below the Gorringe Bank seems the most likely since it is more efficient in reproducing the
    distribution of high intensities in SW Iberia due to the 1755 earthquake.
    http://evunix.uevora.pt/~delphine/PubliFCT08/GRANDIN2007a.pdf

    The Holocene record of tsunamis in the southwestern Iberian Margin: date and
    consequences of the next tsunami
    El registro holoceno de tsunamis en el margen ibérico suroccidental: fecha y
    consecuencias del próximo tsunami

    http://gte526.geoma.net/uploads/122469733580Abstract Geodesia.pdf


    LE GRAND TREMBLEMENT DE TERRE DE LISBONNE
    Le mécanisme de subduction ayant causé le séisme qui a détruit
    la capitale portugaise, il y a 250 ans, aurait été découvert.
    http://perso-sdt.univ-brest.fr/~gutscher/pourlascience.pdf

    Impact of a Lisbon-type tsunami on the U.K. coastline and the
    implications for tsunami propagation over broad continental shelves

    http://nora.nerc.ac.uk/5391/1/horsburgh_-_impact_of_a_lisbon_type_tsunami.pdf


    The effects of the 1755 Lisbon earthquake and tsunami on the Algarve Region, Southern Portugal
    The 1755 Lisbon earthquake (magnitude ~8-5Mw) killed between 15 and 20,000 people, of whom an estimated 1,020 lived in the Algarve. The earthquake cost Portugal between c.32 and 48% of its Gross Domestic Product, probably making it financially the greatest natural catastrophe to have affected western Europe. Using a combination of archival information and data collected in the field, this paper discusses: the devastating effects of the earthquake and tsunami on the economy, society and major settlements in the Algarve; and recovery of the region in the years that followed. Today the Algarve is one of Europe’s principal tourist destinations and a region vital to the Portuguese economy. The 1755 earthquake was not a one off event and the Algarve, which now houses a resident population of over 400,000 – a figure that more than doubles with tourists in the summer months, is highly exposed to earthquakes and tsunamis. An earthquake of similar size (minimum estimated recurrence 614±105 years), is viewed as a worse-case future scenario. Although strict building codes which apply to the whole country were pioneered in Portugal following 1755 and have been revised on many occasions, there is a recognised need for more detailed hazard maps and emergency plans for the Algarve. These have already been produced for Lisbon and in the Algarve a start has been made, where a tsunami risk map has recently been completed for Portimão concelho (i.e. county).
    http://research-archive.liv.ac.uk/742/5/742.pdf

    The 1755 Lisbon Tsunami in Guadeloupe Archipelago: Source Sensitivity
    and Investigation of Resonance Effects

    On the 1st of November 1755, a major earthquake of estimated Mw=8.5/9.0 destroyed Lisbon (Portugal) and
    was felt in whole Western Europe. It generated a huge tsunami which reached coastlines from Morocco to Southwestern
    England with local run-up heights up to 15 m in some places as Cape St Vincent (Portugal). Important waves were reported
    in Madeira Islands and as far as in the West Indies where heights of 3 m and damages are reported. The present
    knowledge of the seismic source(s), presented by numerous studies, was not able to reproduce such wave heights on the
    other side of the Atlantic Ocean whatever the tested source. This could be due to the signal dispersion during the propagation
    or simply to the lack of simulations with high resolution grids. Here we present simulations using high resolution
    grids for Guadeloupe Archipelago for two different sources. Our results highlight important wave heights of the range of 1
    m to more than 2 m whatever the source mechanism used, and whatever the strike angle in some particular coastal places.
    A preliminary investigation of the resonance phenomenon in Guadeloupe is also presented. In fact, the studies of long
    wave impact in harbours as rissaga phenomenon in the Mediterranean Sea leads us to propose the hypothesis that the 1755
    waves in the West Indies could have been amplified by resonance phenomenon.
    Most of the places where amplification takes place are nowadays important touristic destinations.
    http://www.benthamscience.com/open/tooceaj/articles/V004/SI0042TOOCEAJ/58TOOCEAJ.pdf

    Tsunami Calculation of the 1755 Lisbon Earthquake
    The generation of destructive tsunamis in the Gulf of Cadiz, at the eastern end of the Azores–
    Gibraltar plate boundary, was studied by numerical modelling of the historical 1755 Lisbon
    tsunami. The Lisbon Earthquake is one of the first major events of this kind that is relatively
    well documented by historical sources in this region. Lisbon earthquake tsunami was the most
    deadly tsunamis on Lisbon coasts.
    The report shows calculations of wave generation, time of propagation and elevation of the
    waves on coastal regions surrounding the Gulf of Cadiz.
    http://lunar.jrc.it/tsunami/temp/fi...culation of the 1755 Lisbon Earthquake v2.pdf

    Far field tsunami simulations of the 1755 Lisbon earthquake: Implications for tsunami
    hazard to the U.S. East Coast and the Caribbean

    The great Lisbon earthquake of November 1st, 1755 with an estimated moment magnitude of 8.5–9.0 was the
    most destructive earthquake in European history. The associated tsunami run-up was reported to have
    reached 5–15 m along the Portuguese and Moroccan coasts and the run-up was significant at the Azores and
    Madeira Island. Run-up reports from a trans-oceanic tsunami were documented in the Caribbean, Brazil and
    Newfoundland (Canada). No reports were documented along the U.S. East Coast. Many attempts have been
    made to characterize the 1755 Lisbon earthquake source using geophysical surveys and modeling the nearfield
    earthquake intensity and tsunami effects. Studying far field effects, as presented in this paper, is
    advantageous in establishing constraints on source location and strike orientation because trans-oceanic
    tsunamis are less influenced by near source bathymetry and are unaffected by triggered submarine
    landslides at the source. Source location, fault orientation and bathymetry are the main elements governing
    transatlantic tsunami propagation to sites along the U.S. East Coast, much more than distance from the source
    and continental shelf width. Results of our far and near-field tsunami simulations based on relative
    amplitude comparison limit the earthquake source area to a region located south of the Gorringe Bank in the
    center of the Horseshoe Plain. This is in contrast with previously suggested sources such as Marqués de
    Pombal Fault, and Gulf of Cádiz Fault, which are farther east of the Horseshoe Plain. The earthquake was
    likely to be a thrust event on a fault striking ~345° and dipping to the ENE as opposed to the suggested
    earthquake source of the Gorringe Bank Fault, which trends NE–SW. Gorringe Bank, the Madeira-Tore Rise
    (MTR), and the Azores appear to have acted as topographic scatterers for tsunami energy, shielding most of
    the U.S. East Coast from the 1755 Lisbon tsunami. Additional simulations to assess tsunami hazard to the U.S.
    East Coast from possible future earthquakes along the Azores–Iberia plate boundary indicate that sources
    west of the MTR and in the Gulf of Cadiz may affect the southeastern coast of the U.S. The Azores–Iberia plate
    boundary west of the MTR is characterized by strike–slip faults, not thrusts, but the Gulf of Cadiz may have
    thrust faults. Southern Florida seems to be at risk from sources located east of MTR and South of the Gorringe
    Bank, but it is mostly shielded by the Bahamas. Higher resolution near-shore bathymetry along the U.S. East
    Coast and the Caribbean as well as a detailed study of potential tsunami sources in the central west part of
    the Horseshoe Plain are necessary to verify our simulation results.
    http://www.whoi.edu/science/GG/people/jlin/papers/Barkan_tenBrink_Lin_Mar_Geol_2009.pdf


    Lisbon 1755: A Case of Triggered Onshore Rupture?
    It has been widely recognized, both in classical and in modern studies,
    that the Lisbon earthquake of 1755 was a multiple event, composed of three shocks
    separated by a few minutes (see, e.g., Reid, 1914). Attempts to constrain the location
    of the source have led to a diversity of proposals, reflecting apparent contradictions
    in the data. The tsunami and damage along the south and southwest Iberian coast
    and in Morocco favor an offshore source, whereas the presence of an additional zone
    of strong shaking in the Lower Tagus Valley (LTV), near Lisbon, favors a more
    northerly location. By combining the contemporary accounts with intensity data from
    other earthquakes, we favor a compound source with a large distance between the
    faults. We propose that, although the mainshock was offshore, the resulting stress
    changes induced the rupture of the LTV fault, at a distance on the order of 350 km
    (but subject to large uncertainty in the offshore location), a few minutes after the
    mainshock. We favor this model, rather than site effects causing high intensities in the
    Lisbon area, because the highest intensities show a negative correlation to soft soil.
    Several other phenomena described in the eyewitness accounts can also be explained
    by the local rupture now proposed, such as a tsunamilike wave in the Tagus River,
    ground deformation affecting the course of the Tagus River, and the spatial pattern
    of damaging aftershocks. Recognition of this “missing” episode of rupture on the
    LTV fault significantly changes the hazard estimate for the Lisbon area.
    http://mahabghodss.net/NewBooks/www/web/digital/nashrieh/bssa/2003/october 93 (5)/2056.pdf

    THE EARTHQUAKES AND THE TSUNAMI OF 1755 and 2004 – HISTORIC ACCIDENTS?
    This paper is about the interpretation of the 1755 Lisbon earthquake as a
    historic accident. The paper is divided in two main parts: the commemoration of the 250th
    anniversary of the 1755 Lisbon earthquake in 2005 and the reaction to other times, as
    today. Especially a comparison is highlighted, the reaction to the 2004 Sumatra earthquake
    and Indian Ocean tsunami in 2005 and today, as, contrary to what happened immediately
    after, the 2004 event did not cause a discourse. Also compared to other historical events
    mentioned, the Lisbon earthquake remains the only historic accident, and one of the birth
    dates of modernity. Some key aspects are discussed, as the issue of ruins, or of rebuilding,
    in context of the 18th century and today. Overall, the accent lays on the view from the
    Humanities, not of earthquake engineering, and reviews such views at the events and
    publications about the earthquake.
    http://www.ce.tuiasi.ro/~bipcons/Archive/195.pdf




    High Resolution Tsunami Modelling for the Evaluation of Potential Risk
    Areas in Setubal

    Modeling has a relevant role in today’s natural hazards mitigation planning as it can cover a wide range of natural
    phenomena. This is also the case for an event like a tsunami. In order to support the urban planning or prepare
    emergency response plans it is of major importance to be able to properly evaluate the vulnerability associated
    with different areas and/or equipments. The use of high resolution models can provide relevant information about
    the most probable inundation areas which complemented with other data such as the type of buildings, location of
    prioritary equipments, etc., may effectively contribute to better identify the most vulnerable zones, define rescue
    and escape routes and adequate the emergency plans to the constraints associated to these type of events.
    In the framework of FP6 SCHEMA project these concepts are being applied to different test sites and a detailed
    evaluation of the vulnerability of buildings and people to a tsunami event is being evaluated. One of the sites
    selected it is located in Portugal, in the Atlantic coast, and it refers to Setúbal area which is located about 40
    km south of Lisbon. Within this site two specific locations are being evaluated: one is the city of Setúbal (in the
    Sado estuary right margin) and the other is the Tróia peninsula (in the Sado estuary left margin). Setúbal city is a
    medium size town with about 114,000 inhabitants while Tróia is a touristic resort located in a shallow area with a
    high seasonal occupation and has the river Sado as one of the main sources of income to the city.
    Setúbal was one of the Portuguese villages that was seriously damaged by the of 1755 earthquake event. The 1755
    earthquake, also known as the Great Lisbon Earthquake, took place on 1 November 1755, the catholic holiday of
    All Saints, around 09:30 AM. The earthquake was followed by a tsunami and fires which caused a huge destruction
    of Lisboa and Setúbal
    In the framework of the present study, a detailed evaluation of the site vulnerability to a tsunami event based on the
    consideration of the wave heights, buildings type and access routes characteristics was performed. The wave height
    and most probable inundation areas was made on the basis of the simulation of three earthquake potential sources
    with different level of impact (extreme, moderate and weak) in the Setúbal area. In the case of the extreme event
    the selected source for simulation corresponds to an interpretation of the origins of the 1755 earthquake proposed
    by Baptista et al (2003).In this study it is suggest that the 1755 tsunami event had two sources: one located in the
    Marques de Pombal thrust (MPTF) and a second one located in the Guadalquivir Bank. The other two sources are
    based on a study done by Omira et al (2009) regarding the design of a Sea-level Tsunami Detection Network for
    the Gulf of Cadiz. In the framework of this study there are analyzed different areas of seismic activity in the South
    of Portugal and proposed some possible earthquake sources and characteristics.
    The tsunami propagation simulations were performed using MOHID modelling system which is an open source
    three-dimensional water modelling system, developed by Hidromod and MARETEC (Marine and Environmental
    Technology Research Center - Technical University of Lisbon).
    As a result of the study detailed inundation maps associated to the different events and to different tide levels were
    produced. As a result of the combination of these maps with the available information of the city infrastructures
    (building types, roads and streets characteristics, prioritary buildings, etc.) there were also produced high scale
    vulnerability maps, escape routes, emergency routes maps.
    http://www.schemaproject.org/IMG/pdf/EGU2010-13241.pdf



    The 1755 Lisbon Tsunami: Tsunami Source Determination and its Validation
    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.
    http://www.fujipress.jp/finder/prev....pdf&frompage=abst_page&pid=1246&lang=English



    TSUNAMI PROPAGATION ALONG TAGUS ESTUARY (LISBON, PORTUGAL) PRELIMINARY RESULTS
    In this study we present preliminary results of flood calculation along Tagus Estuary, a catastrophic event that happened several times in the past, as described in historical documents, and that constitutes one of the major risk sources for Lisbon coastal area. To model inundation we used Mader’s SWAN model for the open ocean propagation with a 2 km grid, and Imamura’s TSUN2 with a 50 m grid covering the entire estuary. The seismic source was computed with the homogeneous elastic half space approach. Modelling results agree with historical reports. Synthetic flood areas correspond to the sites where there are morphological and sedimentary evidences of two known major events that stroke Lisbon: 1531-01-26 and 1755-11-01 tsunamis.
    http://tsunamisociety.org/245baptista.pdf



    The Atlantic Tsunami on November 1st, 1755:
    World Range and Amplitude According to
    Primary Documentary Sources

    On Saturday, November 1st, 1755, at about 9:40, Lisbon underwent the strongest
    tsunamigenic earthquake ever reported by witnesses in Western Europe. Many people,
    attending the religious offices of All Hallows, were killed by the collapse of churches. Some
    took refuge on the quays of the Tagus, attempting to escape the fall of debris from
    collapsing buildings and to flee on boats: but a tsunami, 5 to 10 m high according to various
    accounts, struck downtown Lisbon. Fire outbreaks, lit by houses collapsing on their kitchen
    fire, set the town to flames, which raged for almost one week.
    The event triggered a competition between Scientific Institutions and between Gazettes to
    provide their members or readers with original accounts: a reaction similar to what we
    witnessed on the WEB after the December 26th, 2004 earthquake in Sumatra. In that case,
    thanks to the speed at which the information now travels, and constraint provided by
    photography and video-movies, the result has been the gathering of a rich array of accurate
    observations and data. At variance, in 1755-56, under the escalation of the competition
    between institutions or journals, with a small number of qualified observers and slow travel
    of letters conveying the accounts, the exaggerations of compilers were let loose. The
    reliability of the testimonies suffered in the process: many are contradictory, both in terms of
    lack of internal consistency and of contradiction between reports.
    The Andaman-Sumatra earthquake and tsunami have awoken a public awareness of the risk
    of tsunami. The November 1st, 1755 tsunami caused by the Great Lisbon Earthquake,
    remains the only destructive event of the kind on the European Atlantic shores to have been
    described in some detail in the past, partly supplemented by the tsunami of March 31st,
    1761. The primary accounts of the 1755 event are in no danger to loose their documentary
    importance : the simulations now attempted to evaluate the tsunami risk to human lives and
    coastal settlements must be constrained by "real data, deducted from historical reports"
    (Mendes-Victor et al., 2005). But the data gathered from such reports are so dispersed that
    they cannot be applied without a critical analysis.
    http://www.intechopen.com/download/pdf/pdfs_id/13093




    The Opportunity of a Disaster
    The Economic Impact of the 1755 Lisbon Earthquake

    http://www.york.ac.uk/res/cherry/docs/Alvaro3.pdf

    Review of the historical seismicity in the Gulf
    of Cadiz area before the 1 November 1755 earthquake.
    An intermediate report

    The subproject "Review of the historical seismicity in the Gulf of Cadiz area before the 1 Nov. 1755 earthquake" is included in a more vast project - "Review of historical seismicity in Europe" - the aim of which is to establish a common methodology among European seismologists and historians on research of historical seismicity and to get a significant set of data on earthquake potential and effects. In this report, which corresponds to the whole period of the execution of the project (1989-91), are referred the main results obtained. The execution of this project is under the responsibility of the National Institute for Meteorology and Geophysics of Portugal and the National Geographic Institute of Spain. It is believed that the long-term precedent research carried out in Portugal immediately before the beginning of this project (Moreira, 1984; 1991; Runa e Morais Freire, 1985; Themudo Barata et al., 1988; 1989) and by Pereira de Sousa (1919-32) in the second and third decades of the present century led to the acquisition of a large part of the existing data about the earthquakes that occurred after the 16th century. Anyway, research in libraries and archives continued both in Portugal and Spain during the period covered by this project and several reports were produced showing the results. Meetings to examine the state-of-the-art of the project and define the methodology, in which participated Dr. Stucchi, coordinator of the project "Review of historical seismicity in Europe", Dr. Paola Albini, historian who assists Dr. Stucchi, the Portuguese and Spanish groups were held in Lisbon in 1989 and 1990. In 1989 and 1990 was paid special attention to the research in archives and libraries in Algarve and Alentejo - the southernmost provinces of Portugal - the most affected regions by earthquakes which occurred in the period covered by the project. In Spain a research was carried out in 1990 in several archives and libraries of the southwestern part of the country (Moreira, 1990). In the last part of 1990 and 1991 was made an intense research in the National Archive of Torre do Tombo in Lisbon, looking for documentation of the main convents and for documentation left by diarists, journalists, members of the diplomatic body and other erudite people, following the recommendations of Dr. Stucchi in his note of June 1990 "Remarks and recommendations after the first year".
    http://emidius.mi.ingv.it/RHISE/i_15sou/i_15sou.html


    Impact of a 1755-like tsunami in Huelva, Spain
    Coastal areas are highly exposed to natural hazards
    associated with the sea. In all cases where there is historical
    evidence for devastating tsunamis, as is the case of
    the southern coasts of the Iberian Peninsula, there is a need
    for quantitative hazard tsunami assessment to support spatial
    planning. Also, local authorities must be able to act towards
    the population protection in a preemptive way, to inform
    “what to do” and “where to go” and in an alarm, to make
    people aware of the incoming danger. With this in mind, we
    investigated the inundation extent, run-up and water depths,
    of a 1755-like event on the region of Huelva, located on the
    Spanish southwestern coast, one of the regions that was affected
    in the past by several high energy events, as proved by
    historical documents and sedimentological data. Modelling
    was made with a slightly modified version of the COMCOT
    (Cornell Multi-grid Coupled Tsunami Model) code. Sensitivity
    tests were performed for a single source in order to understand
    the relevance and influence of the source parameters
    in the inundation extent and the fundamental impact parameters.
    We show that a 1755-like event will have a dramatic
    impact in a large area close to Huelva inundating an area between
    82 and 92 km2 and reaching maximum run-up around
    5 m. In this sense our results show that small variations on
    the characteristics of the tsunami source are not too significant
    for the impact assessment. We show that the maximum
    flow depth and the maximum run-up increase with the average
    slip on the source, while the strike of the fault is not
    a critical factor as Huelva is significantly far away from the
    potential sources identified up to now. We also show that
    the maximum flow depth within the inundated area is very
    dependent on the tidal level, while maximum run-up is less
    affected, as a consequence of the complex morphology of the
    area.
    http://www.nat-hazards-earth-syst-sci.net/10/139/2010/nhess-10-139-2010.pdf


    THE 1755 LISBON EARTHQUAKE AND THE GENESIS OF THE RISK MANAGEMENT CONCEPT
    The 1755 Lisbon earthquake is a landmark in the western cultural history by different reasons and perspectives.
    In fact, one of the most important cities in Europe was almost destroyed and a large number of people died due to the
    buildings collapse, fire and tsunami effects.
    Within the European cultural framework of the XVIII century this event was a shock. The scientific,
    philosophical, religious and moral consequences of the disaster were discussed and the Lisbon earthquake was a
    catalyst for relevant changes.
    At the epoch, the risk analysis and management concepts were still not created as disciplines. However, the
    Lisbon earthquake can also be considered as a very strong landmark in the genesis of the risk management applied to
    disasters as it is now considered. Based on historical sources and narratives this evidence can be shown: the most
    relevant actions developed after the earthquake can be interpreted as components of a risk management structure. The
    author describes the contributions that can be detected in what concerns: event identification and explanation; crisis
    response; mitigation and prevention and vulnerability concept.
    http://www.civil.ist.utl.pt/~joana/.../final-artigo ABA-terramoto-internacional.pdf


    The record of the tsunami produced by the 1755 Lisbon
    earthquake in Valdelagrana spit (Gulf of Cádiz, southern Spain)

    Severalwashover fans breaking through the spit of Valdelagrana existing in middle 18th Century in the
    Cuadalete estuary (Bay of Cadiz) are interpreted as the trace of the exceptional tsunami generated by the
    AD 1755 Lisbon earthquake, based on geological, morphological and historical arguments.
    http://eprints.ucm.es/10711/1/1998_2_Tsunami_GG.pdf


    Earthquakes and tsunami in November 1755 in Morocco: a
    different reading of contemporaneous documentary sources

    Tsunami seldom strike the European Atlantic
    shores. The great Lisbon Earthquake of 1 November 1755
    is the main destructive tsunamigenic event recorded. Since
    the mid-1990’s, many simulations of propagation of tsunami
    waves from variants of the possible seismic source have been
    conducted. Estimates of run-up in Morocco are seldom included
    in publications, maybe for want of reliable historical
    data to control the simulations. This paper revisits some early
    accounts, transmitted as translations to European Chanceries,
    Scientific Societies and Newspapers. A critical analysis of
    the documents leads us to conclude that the Lisbon earthquake
    was overestimated because of amalgamation with a
    later Rifian earthquake. Then, the overestimation of the
    tsunami through worst interpretation of the scant data available
    appeared only reasonable, while the moderate measurements
    or interpretations were not given their due attention. In
    Morocco the amplitude of the tsunami (i.e. height at shoreline
    minus expected tide level) may not have exceed the measurement
    given by Godin (1755) for Cadiz, 2.5m above the
    calculated astronomical tide, a crest-to-trough amplitude of
    5m at most. This age-old overestimation of both the earthquake
    and tsunami is detrimental to the evaluation of the risk
    for coastal people and activities.
    http://www.nat-hazards-earth-syst-sci.net/9/725/2009/nhess-9-725-2009.pdf


    TSUNAMI RELICS ON THE COASTAL LANDSCAPE WEST OF LISBON, PORTUGAL
    Lisbon and the mouth of the river Tagus (Tejo) are known to have suffered from the great
    earthquake and tsunami of November 1st, 1755. Whereas historical sources mention tsunami
    waves and describe inundation in Lisbon, field evidence from this event has been found only
    along the Algarve coast and the Spanish Atlantic coast in the south. Our observations in the Cabo
    da Roca-Cascais area west of Lisbon resulted in the discovery of several very significant tsunami
    relics in the form of single large boulders, boulder ridges, pebbles and shells high above the
    modern storm level. Deposition of large amounts of sand by the tsunami waves has intensified
    eolian rock sculpturing. Abrasion of soil and vegetation still visible in the landscape may point to
    the great Lisbon event of only some 250 years ago, but radiocarbon and ESR datings also yielded
    older data. Therefore, we have evidence that the Portuguese coastline has suffered more than
    one strong tsunami in the Younger Holocene.
    http://library.lanl.gov/tsunami/231/scheff.pdf



    The 1755 tsunami propagation in Atlantics and its effects on the French
    West Indies

    http://meetingorganizer.copernicus.org/EGU2009/EGU2009-502.pdf


    The Lisbon Earthquake of 1755
    – Public Distress and Political Propaganda

    This article examines the impact of the Lisbon earthquake on the international political sphere.
    The shock waves of the event reflected the basic ideological traits of the eighteenth century. For
    the first time in the western world, the press helped to create the illusion of proximity and unity
    among the peoples of different European nations. Furthermore, the 1755 earthquake launched
    the modern debate on how to think and act in a world where such catastrophes are likely to
    occur.
    On the eve of the Seven Years’ War, the destruction of the capital of the Portuguese empire also
    triggered diplomatic and political reactions. Pombal’s attempt to turn Portugal into a prosperous
    and politically strong country contributed towards minimising the disruptions to social and
    economic routines. Against the backdrop of the 1755 earthquake, and using the European war
    as an immediate cause, the Marquis of Pombal, minister of King Joseph I, laid the foundations
    for a press policy commensurate with the scale of the catastrophe.
    http://www.brown.edu/Departments/Portuguese_Brazilian_Studies/ejph/html/issue7/pdf/aaraujo.pdf
     
    ecobcg gostou disto.
  6. Gilmet

    Gilmet
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    Sismo de 1755 mudou a vida de Voltaire
     
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  7. Mário Barros

    Mário Barros
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    Furacão

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    Prejuízos do sismo de 1755 calculados em 75% do PIB

    Cerca de 100 mil contos da época, correspondentes a 75% do PIB anual português em meados do século XVIII, é o cálculo que José Luís Cardoso, professor catedrático do ISEG, em Lisboa, faz sobre os prejuízos provocados pelo terramoto de 1755.

    A catástrofe do dia de Todos-os-Santos foi devastadora e as perdas não se limitaram à derrocada de palácios e igrejas edificados com o ouro do Brasil, no então recente reinado de D. João V. Também há que contabilizar um riquíssimo património móvel, em jóias, obras de arte e dinheiro vivo que na época era só metálico. E as somas a que se chega são tão astronómicas que José Luís Cardoso, professor de História da Economia, verificou uma grande dissonância e notórios exageros quando investigou os valores referidos na época e que vão de 85 mil a 375 mil contos, com os mercadores estrangeiros, sobretudo ingleses, a queixarem-se de perdas na ordem dos 40 mil contos. Numa primeira abordagem, avaliou o volume dos prejuízos em 230 mil contos da época, mas ao confrontar esse valor com o que seria, então, o PIB considerou os números excessivos. Numa estimativa mais apertada aponta, agora, para 100 mil contos, correspondentes na altura a 75% da riqueza total produzida durante um ano em Portugal.

    INCOMENSURÁVEL
    Sobre os prejuízos do terramoto que estendeu a destruição por todo o Sul do País, desde Vila Real de Santo António a Castelo de Vide, na fronteira espanhola, e até à Ericeira, na costa Atlântica, José Luís Cardoso considera que há muito trabalho de arquivo por fazer. E quando houver resultados ter-se-á de admitir que mesmo os cálculos mais reduzidos podem parecer um exagero, já que os estragos foram incomensuráveis.
    José Luís Cardoso tem uma comunicação intitulada ‘Pombal, o Terramoto e a política de regulação económica’, anunciada para dia 4, no colóquio Terramoto de 1755 – Impactos Históricos, promovido pelo ISCTE e o ICS, em que abordará as consequências económicas da catástrofe sob outras perspectivas. A sua apreciação sobre as decisões de Sebastião José de Carvalho e Melo, futuro Marquês de Pombal, é muito positiva: ‘A sua preocupação foi evitar que os preços aumentassem, que houvesse um açambarcamento de bens alimentares, naturalmente escassos, ou que os salários subissem, além de tomar medidas de abastecimento, segurança dos cidadãos e saúde pública”, explica José Luís Cardoso, observando que para a reconstrução de Lisboa o reino criou apenas um novo imposto de mais 4% nos direitos alfandegários sobre as mercadorias importadas. Não havia que massacrar mais uma economia portuguesa em fase depressiva. O terramoto acabou até por ajudar ao crescimento.

    "ECONOMIA RECUPEROU NUM TEMPO CURTO"
    (José Vicente Serrão, presidente do Departamento de história do ISCTE, promove colóquio sobre 1755)


    Correio da Manhã – Quais foram as consequências económicas do Terramoto?
    José Vicente Serrão – O impacto foi tanto mais dramático quanto se veio inserir numa conjuntura crítica que vinha de trás e, em muitos dos seus aspectos, nada teve a ver com o Terramoto. Para a fase depressiva, que marca a economia portuguesa entre os meados da década de 1750 e os princípios da de 1770, contribuíram o declínio das chegadas de ouro do Brasil, a contracção do comércio externo, as dificuldades do mercado internacional de açúcar e tabaco, a crise de exportação dos vinhos, o extraordinário aumento das despesas inerentes à entrada de Portugal na Guerra dos Sete Anos, entre outros factores.
    O Terramoto teve, obviamente, a sua quota-parte, mas estamos longe de poder fixá-la. Em contrapartida, não podemos deixar de assinalar as consequências positivas. A reconstrução abriu novas oportunidades de negócio. Os sectores da construção naval e da construção civil, pública e privada, foram os primeiros a aproveitá-las, para não falar dos reflexos adicionais em todas as indústrias a montante (cal, tijolo, pedra, vidros, ferragens, madeiras). A procura de mão-de-obra dinamizou o mercado de trabalho e de serviços. O mercado imobiliário e o mercado de capitais conheceram uma animação sem precedentes.
    – Quanto tempo foi necessário para recuperar?
    – Foi muito variável. Dou apenas quatro exemplos. O principal porto da capital, as alfândegas e os respectivos armazéns foram imediatamente transferidos para a zona de Belém e Junqueira e voltaram a estar operacionais em menos de dois meses; o abastecimento da população em bens de primeira necessidade foi restabelecido em poucas semanas ou meses; em contrapartida, 25 anos mais tarde, ainda se faziam contratos de aforamento de quintas sob a justificação de que os seus proprietários não tinham dinheiro para reparar instalações produtivas, arruinadas desde o tempo do Terramoto; no mesmo sentido, a reconstrução do património urbano arrastou-se até bem entrado o século XIX.
    Num balanço global, agora à distância de 250 anos, pode dizer-se que a economia recuperou do abalo sofrido num tempo bastante mais curto do que aquilo que se poderia esperar, tendo em conta a dimensão dos estragos.

    INICIATIVAS
    IMPACTOS HISTÓRICOS

    De 3 a 5 de Novembro, decorre no ISCTE, à cidade Universitária, em Lisboa, o colóquio internacional ‘Terramoto de 1755 - Impactos Históricos” que reunirá 70 especialistas de uma dezena de países e tem na comissão organizadora Ana Cristina Araújo (Faculdade de Letras de Coimbra), José Luís Cardoso (ISEG-UTL), José Vicente Serrão (ISCTE), Nuno Gonçalo Monteiro (ICS-UL) e Walter Rosa (Faculdade de Ciências de Coimbra).
    REAL ÓPERA DO TEJO
    Excertos das óperas estreadas na Ópera do Tejo, que teve só um ano de existência no Terreiro do Paço, junto ao Palácio Real, até à sua completa destruição pelo terramoto, serão interpretados pela Orquestra Metropolitana de Lisboa no dia 1, às 21h30, na Igreja de São Domingos, ao Rossio, em Lisboa. O programa inclui obras de David Perez, António Mazzoni, António Teixeira e João Sousa Carvalho, compositor de um ‘Te Deum’.

    ACTOS RELIGIOSOS
    Em memória das vítimas do Terramoto de 1755 e de todas as outras catástrofes naturais em todo o Mundo, o cardeal--patriarca D. José Policarpo celebra missa no dia de Todos os Santos, às 9h30, nas ruínas do Convento do Carmo, em Lisboa, destruído pelo sismo. Para a mesma hora, está convocado o repicar dos sinos de todas as igrejas da cidade. Às 16h00, haverá um concerto e a apresentação das obras de recuperação na igreja da Madalena, na colina da Sé, e às 19h00 será a vez de D. Manuel Clemente, bispo auxiliar de Lisboa, celebrar na igreja de S. Nicolau, onde também decorre uma acção de restauro do património.

    CM
    http://www.cmjornal.xl.pt/detalhe/n...izos-do-sismo-de-1755-calculados-em-75-do-pib
     
  8. Gerofil

    Gerofil
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    Lisboa ainda não possui uma carta de risco sísmico
    Por Fernanda Ribeiro
    01.11.2005
    Duzentos e cinquenta anos após o terramoto que destruiu grande parte da cidade de Lisboa, a capital ainda não dispõe de uma verdadeira Carta de Risco Sísmico, que cruze toda a informação disponível sobre solos, parque edificado e infra-estruturas subterrâneas. Apenas o Plano de Emergência elaborado pelo serviço municipal de protecção civil dispõe de "uma aproximação muito razoável" desse documento, no capítulo das "áreas críticas de risco", considera Carlos Sousa Oliveira, presidente da Sociedade Portuguesa de Engenharia Sísmica (SPES).


    Entre as áreas que seriam mais duramente atingidas por um sismo figuram algumas ocupadas por novas urbanizações, como o Parque das Nações e algumas zonas do Lumiar. A restante zona ribeirinha oriental, desde o Jardim do Tabaco a Xabregas, Beato e Matinha, e a zona ribeirinha ocidental, de Algés a Pedrouços, Alcântara, Santos-o-Velho, S. Paulo e Cais do Sodré, estão também incluídas nas áreas de maior risco.

    O Chiado e a Baixa, a colina do Castelo e a Graça, a Av. da Liberdade, Praça da Alegria, Santa Marta e Pena, e ainda a Av. Almirante Reis, do Martim Moniz, passando por Anjos, Arroios, Penha de França seriam igualmente muito afectados, a par do Vale da Estrada de Benfica e alguns pontos do Lumiar, de Carnide e do Vale de Chelas.

    "Ter uma carta única seria muito vantajoso, para se ter uma ideia um pouco mais concreta de como planear a emergência e até para ser usada em termos de ordenamento do território", afirma Sousa Oliveira, especialista em engenharia sísmica que foi um dos pioneiros a trabalhar na área da prevenção e da redução do risco e que participou também nos estudos desenvolvidos pela Câmara Municipal de Lisboa.

    "O que há são cenários para vários tipos de sismos, obtidos com simuladores. O do Laboratório Nacional de Engenharia Civil (LNEC) é mais evoluído e tem dados mais actualizados (ver texto na página ao lado). O da protecção civil municipal, ainda que menos sofisticado, vai mais ao detalhe do quarteirão. Há também uma proposta de classificação de vulnerabilidade dos solos e, além disso, no plano de emergência de Lisboa há as áreas críticas de risco sísmico, que incluem vários parâmetros (tipo de solos, edificado, e acessos) que nos dão já uma boa aproximação do que há-de vir a ser uma primeira carta de risco", salienta este especialista em engenharia sísmica.

    Nessas áreas críticas, sublinha Sousa Oliveira, "não se diz à partida que é impossível construir, mas é sabido que teremos que ter outros cuidados especiais, e não basta aplicar os regulamentos existentes".

    Quanto à interrogação que muitos se colocam - "estará Lisboa preparada para um sismo ?" -, Carlos Sousa Oliveira, conhecedor da matéria, acha a questão "complicada".

    "Se for um sismo muito grande, semelhante ao de 1755, é pouco provável e haverá que pedir ajuda internacional, à União Europeia. Os sismos intermédios já provocam alguns problemas complicados, principalmente no parque edificado mais antigo. Os danos vão depender muito da localização desse parque, se está em zonas melhores ou piores, e depende também do próprio tipo de sismo."

    Um outro fenómeno que pode surgir em consequência de um sismo forte é o dos deslizamentos e aí também o plano de emergência detecta áreas da cidade que serão mais atingidas, consoante o tipo de sismo.

    A incógnita da qualidade da construção

    Além disso, há um factor que é praticamente desconhecido, porque não é fiscalizado: "A qualidade dos edifícios é ainda uma coisa que não conhecemos bem, porque uma coisa é dizer que eles são projectados e construídos segundo as normas e os actuais regulamentos anti-sísmicos, mas outra coisa é não serem cumpridos esses procedimentos" - o que pode ter resultados catastróficos imprevisíveis.

    "Nunca foi feito um estudo detalhado, ou por amostragem, que revele até que ponto são cumpridos os regulamentos. E isso é uma matéria que interessa a todos, em particular à Câmara de Lisboa. Esse parâmetro não tem entrado minimamente nos dados introduzidos nos simuladores", diz este especialista, para quem "seria interessante que as seguradoras também pudessem intervir, para se controlar melhor a qualidade".

    Para apurar se Lisboa está efectivamente preparada, seria também muito útil testar o plano de emergência. "Ele nunca foi testado, o que seria úti,l porque as primeiras 48 horas após um sismo são críticas em termos de salvar pessoas e bens", salienta Sousa Oliveira.

    "O que se tem feito cá são exercícios de gabinete, em que se simulam colapsos de edifícios e que põem muitas entidades a mexer, entre as que habitualmente terão que intervir. Isso também ajuda muito. Um teste real é mais complicado, obrigaria a parar a cidade, o que é difícil", admite Sousa Oliveira.

    Mas, recorda, "havia a ideia de criar um cenário de desastre, juntando em dois ou três sítios da cidade as entidades envolvidas na emergência e durante um ou dois dias desencadear acções, mas nunca chegou a concretizar-se. Em Los Angeles, todos os anos fazem exercícios deste género".

    Há cerca de um ano, a Câmara de Lisboa anunciara a intenção de levar a cabo um teste, simulando um cenário do Plano de Emergência, mas o que acabou por ser feito, embora útil, simulou um desastre diferente, uma colisão envolvendo um camião transportando materiais inflamáveis e um autocarro. O cenário escolhido foi o Parque da Belavista.

    Segundo Álvaro de Castro, presidente do serviço municipal de protecção civil, nesse exercício participaram as mesmas entidades que seriam chamadas a intervir em caso de sismo e foi muito proveitoso, uma vez que permitiu detectar necessidades operacionais.

    "É preciso fazer a inventariação dos meios e recursos necessários e aí há um longo trabalho a fazer. No exercício da Belavista é que percebemos a importância de ter esses dados e uma ideia mais exacta do papel de cada uma das entidades numa situação de emergência", disse ao PÚBLICO.

    "Se forem precisas duas mil tendas, quem as tem e onde as iremos buscar? Se for necessário transferir doentes de um hospital que seja afectado para outro, qual deles tem capacidade? E onde estão as ambulâncias? É este tipo de dados que temos de ter para acorrer a uma emergência", salienta Álvaro Castro.

    Este responsável destaca também a importância de concluir o Plano de Emergência da Área Metropolitana de Lisboa, que está a ser elaborado pelo Serviço Nacional de Bombeiros e Protecção Civil, porque caso haja um sismo muito forte os meios e recursos de um único munícípio, o de Lisboa, não serão suficientes.

    Já quanto ao sistema de comunicações a estabelecer, em caso de desastre, Álvaro Castro considera ser hoje em dia uma questão menos problemática, uma vez que o sistema de trunking actualmente disponível permite garantir as necessárias comunicações.

    Fonte: Publico
     
  9. Vince

    Vince
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    http://dossiers.publico.clix.pt/noticia.aspx?idCanal=1543&id=1237405



    http://dossiers.publico.clix.pt/noticia.aspx?idCanal=1543&id=1237410



     
  10. algarvio1980

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    http://www.cienciahoje.pt/index.php?oid=25196&op=all
     
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  11. Gil_Algarvio

    Gil_Algarvio
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    [​IMG] [​IMG]

    No dia 1 de Novembro de 1755 | Descrição do dia por Jacome Ratton
    “Entre os acontecimentos extraordinários da minha vida não devo omitir a meus filhos o que passei na ocasião do memorável terramoto de Lisboa, que teve lugar no 1.º de Novembro de 1755, pelas nove horas e meia da manhã; e como fosse dia de Todos os Santos, tinha eu ido à missa à Igreja do Carmo, cujo tecto era de abóbada de pedra, e derrubado matou muito povo que ali se achava, de cujo perigo escapei por ter ido mais cedo, e me achar na dita hora nas águas furtadas das minhas casas, mostrando a um comprador uma partida de papel, que nos tinha vindo avariado, e ali se tinha posto a enxugar. Ao sentir o primeiro abalo me ocorreram muitas reflexões tendentes a salvar a minha vida, e não ficar sepultado debaixo das ruínas da própria casa, ou das vizinhas, se descendo as escadas fugisse para a rua; mas tomei o partido de subir ao telhado, nas vistas de que abatendo a casa eu ficasse sempre superior às ruínas. Já quando eu tomei este expediente era tanta a poeira, que, à maneira do mais denso nevoeiro, impedia a vista, a duas braças de distância; só passados alguns minutos, que a dita poeira se foi dissipando, é que eu pude ver o interior das casas vizinhas, por terem caído as paredes fronteiras, até aos primeiros andares, ficando os telhados apenas sustidos pelas paredes divisórias. Seus habitantes, alguns ainda em camisa, correndo espavoridos de uma a outra parte imprecavam os auxílios do Céu, e dos homens, em seu socorro. À vista desta horrível cena, me resolvi descer as escadas, e fugir para a rua, a fim de buscar alguma parte aonde me julgasse mais seguro. Ao descer as escadas encontrei meus pais, que aflitos me buscavam nas ruínas de um grande pano de chaminé que tinha caído, e debaixo do qual me julgavam sepultado. Foi inexplicável o nosso contentamento quando nos encontrámos; mas eu sem perder tempo lhes pedi que me acompanhassem para o largo mais próximo, que era ao fundo da Rua do Alecrim; e encontrando de passagem D. Maria Castre, nossa vizinha, pouco mais ou menos da minha idade, que também fugia, a tomei pelo braço, e seguimos a Rua dos Remolares por cima de entulhos, e muitos corpos mortos, até à beira-mar, aonde nos julgávamos mais seguros. Pouco depois de ali termos chegado, assim como muita gente, se gritou que o mar vinha saindo furiosamente dos seus limites: facto que presenciámos, e que redobrou o nosso pavor, obrigando-nos a retroceder pelo mesmo caminho, e a procurar, pela Rua de S. Roque, o alto da Cotovia, então obras do Conde de Tarouca, depois Patriarcal, e hoje Erário novo, aonde também vieram ter, por diversos caminhos, meus pais, e os parentes da dita senhora, todos na maior inquietação por não saberem uns dos outros, como aconteceu a imenso povo, que procurou aquele sítio descampado, então terras de pão, desde o alto da Rua de S. Bento até à Travessa de Pombal e Cardais de Jesus, havendo apenas algumas casas na rua que vai desde o Pátio do Tijolo, ou obras do Conde de Soure, até à fábrica da seda, que já existia, assim como também a casa de D. Rodrigo, actualmente Imprensa Régia, e o Convento dos Jesuítas, hoje Colégio dos Nobres. O descampado daquele alto dava lugar a descobrir-se a cidade por todos os lados, a qual, logo que foi noite, apresentou à vista o mais horrível espectáculo das chamas que a devoravam cujo clarão alumiava, como se fosse dia, não só a mesma cidade, mas todos os seus contornos, não se ouvindo senão choros, lamentações, e coros entoando o Bendito, ladainhas, e Miserere. Por fortuna o céu se conservava claro e sereno, e o terreno enxuto; por não ter até então havido chuvas, nem as haver por oito dias mais, o que deu ocasião a fazer cada um os arranjos, que lhe permitiam as circunstâncias.
    Na madrugada do dia seguinte me convidou meu pai para o acompanhar às nossas casas, e ver se delas podíamos salvar alguma coisa, principalmente o precioso, livros, e papéis de maior importância. Não foi sem bastante trabalho que nos saímos bem desta empresa; por quanto descendo pela Rua de S. Bento, ainda com poucas casas, atravessámos do Poço dos Negros para o Poço Novo, tomámos a Calçada do Combro, e Rua do Loreto, para descermos ao fundo da Rua do Alecrim, de cujo lugar avistámos já em chamas a propriedade pegada com a nossa casa, restando-nos apenas tempo para tirar os artigos acima ditos, que metemos em um baú, que meu pai por uma banda, e eu por outra trouxemos, por entre chamas em que ardiam as ruas do Alecrim, S. Roque, e S. Pedro de Alcântara, até ao alto da Cotovia, aonde minha mãe nos esperava.
    Dali partimos com o baú em uma besta de carga, que por fortuna apareceu, e nos dirigimos a uma quinta de pessoa da nossa amizade, sita na estrada do Lumiar, adiante do Campo Grande, aonde fomos bem recebidos, e alojados no jardim, debaixo de uma barraca feita de lençóis, e alastrada de colchões, sobre os quais dormiam promiscuamente, e sem se despir, tanto a gente da casa, como a de fora; porque ninguém se animava a dormir debaixo de telha. Os hóspedes eram muitos, e o pouco, comer porque todos tinham receio de se demorar na cozinha, que havia pago em comum era mal feito; e houve tanta escassez de pão, que meu pai, e eu fomos com uma besta de ceirão buscar uma carga a Linhá Pastora nas vizinhanças de Barcarena. Naquela quinta nos demorámos somente os dias necessários, para nos refazer do vestuário indispensável, principalmente roupa branca; visto que não foi possível a cada um salvar mais do que aquela que tinha no corpo.”

    Recordações de Jacome Ratton,Lisboa, (1.ª edição: Londres, 1813) pág. 30-33

    Ler mais sobre este sismo em Revelar Lx: http://bit.ly/1r6dtRN

    Fonte:
    https://www.facebook.com/camaradelisboa/posts/885212821498669
     
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  12. fablept

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    Simulação do tsunami do sismo de 1755


    Resumo em animação de como um sismo, tsunami e incêndio destruiu Lisboa


    A ZDF (canal alemão) produziu um documentário (parece ser bem interessante) sobre o sismo e tsunami de 1755, à cerca de dois anos contactei a ZDF sobre o documentário, responderam a dizer que contactaram os canais portugueses. mas nenhum se mostrou interessado em transmitir o documentário (?).
    Se alguem tiver interessado, que envie um email a algum canal português a perguntar se podem transmitir o documentário a 1 de Novembro do próximo ano (Talvez o National Geographic Portugal poderia estar interessado).
    http://zdf-enterprises.de/en/catalo...istory-biographies/1755-the-lisbon-earthquake
     
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    #12 fablept, 28 Dez 2014 às 17:26
    Última edição: 28 Dez 2014 às 17:40
  13. StormRic

    StormRic
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    Interessante reconstituição embora o tsunami progredindo no Tejo em comparação com as naus me pareça exagerado, teria que atingir 30m de altura pelo menos para produzir aquele deslocamento dos navios o que não é compatível com a profundidade do rio naquele local, a frente teria já rebentado.
     
    AndréFrade gostou disto.
  14. AndréFrade

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    Muito interessante :thumbsup:
     
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  15. camrov8

    camrov8
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    não tens bem noção do que é um tsunami, não a frente da onda que traz problemas mas sim o período, nascido dum dos sismo de maior magnitude não deve ter sido nada bonito, não te esqueças que por pouco não a campo de ourique, daí o ditado rez vez campo de ourique, pega no google earth e vê a cota
     
    #15 camrov8, 28 Dez 2014 às 18:49
    Última edição: 28 Dez 2014 às 18:55

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