scholarly journals The tectonic source of the 1755 Lisbon earthquake and tsunami

1999 ◽  
Vol 42 (1) ◽  
Author(s):  
N. Zitellini ◽  
F. Chierici ◽  
R. Sartori ◽  
L. Torelli
Keyword(s):  
Risk Mitigation ◽  
Historical Earthquakes ◽  
Thrust Fault ◽  
Seismic Survey ◽  
Tectonic Structures ◽  
Active Structure ◽  
Reflection Seismic ◽  
Plate Margin ◽  
Lisbon Earthquake ◽  
Diffuse Seismicity

The SW continental margin of Iberia is affected by several tectonic structures of Cenozoic to Recent age, gen-erated by the dynamics of the Iberia-Africa plate margin. This activity is testified by diffuse seismicity along the eastern portion of the Azores-Gibraltar line. The most important active structure, detected during a reflection seismic survey in 1992, is a thrust-fault, some 50 km long and with dip-slip throw of more than 1 km, located offshore Cabo de S. Vincente. A relocation of historical earthquakes in the area shows that this structure lies very close to the epicentre of the catastrophic 1755 Lisbon earthquake and that it should be the generator of the event. This submarine structure can now be studied for modelization of tsunamis and consequent risk mitigation.

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

2003 ◽  
Vol 3 (5) ◽  
pp. 333-340 ◽  
Author(s):  
M. A. Baptista ◽  
J. M. Miranda ◽  
F. Chierici ◽  
N. Zitellini
Keyword(s):  
North Atlantic ◽  
Seismic Energy ◽  
Seismic Survey ◽  
Tectonic Structures ◽  
Tsunami Waves ◽  
The North ◽  
Lisbon Earthquake ◽  
Historical Observation ◽  
Large Effort ◽  
Central Atlantic

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 Marques 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 Marques 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.

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

2008 ◽  
Vol 14 ◽  
pp. 59-63 ◽  
Author(s):  
F. Tedim Pedrosa ◽  
J. Gonçalves
Keyword(s):  
Land Use Planning ◽  
Disaster Preparedness ◽  
Risk Mitigation ◽  
Seismic Intensity ◽  
Mitigation Measures ◽  
The North ◽  
Lisbon Earthquake ◽  
Moroccan Coast ◽  
Flooded Area ◽  
The One

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 250 m from the coast. In the Southwest part of Algarve the waves reached a height between 10 and 15 m 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.

Yathong Trough deep 2D reflection seismic survey - identifying major structures for the southern Cobar Basin, NSW

2016 ◽  
Vol 2016 (1) ◽  
pp. 1-4
Author(s):  
Rosemary Hegarty ◽  
Astrid Carlton ◽  
Karol Czarnota
Keyword(s):  
Seismic Survey ◽  
Reflection Seismic

The 1755 Lisbon earthquake

2001 ◽  
Vol 25 (3) ◽  
pp. 363-383 ◽  
Author(s):  
David K. Chester
Keyword(s):  
Urban Planning ◽  
Shock Waves ◽  
Hazard Assessment ◽  
Western Europe ◽  
Historical Earthquakes ◽  
Archival Research ◽  
Lisbon Earthquake ◽  
Different Types ◽  
Made In ◽  
Seismic Disaster

Affecting an area of ca. 800 000 km2 and killing up to 100 000 people, the Lisbon earthquake of 1755 is probably the greatest seismic disaster to have struck western Europe. The shock waves of the earthquake placed a temporary brake on the emerging rationalism of the European Enlightenment and attempts to explain the disaster in terms of human sinfulness coloured many contemporary accounts. Notwithstanding these difficulties, through careful archival research it has proved possible to obtain relatively value-free accounts of most aspects of the earthquake and to use these not only to model the physical characteristics of and damage caused by the earthquake, but also to consider the implications for present day hazard assessment and urban planning. This paper reviews the progress that has been made in: identifying source and faulting mechanisms; the processes involved in the generation and impact of tsunamis; damage caused to different types of building and the use being made of historical earthquakes of different sizes - of which the 1755 event is the largest - in defining future hazard scenarios for Lisbon and other areas of Iberia.

3D seismic traveltime tomography imaging of the shallow subsurface at the C O2 SINK project site, Ketzin, Germany

Geophysics ◽  
2009 ◽  
Vol 74 (1) ◽  
pp. G1-G15 ◽  
Author(s):  
Sawasdee Yordkayhun ◽  
Ari Tryggvason ◽  
Ben Norden ◽  
Christopher Juhlin ◽  
Björn Bergman
Keyword(s):  
Velocity Structure ◽  
Velocity Model ◽  
Geological Structure ◽  
Seismic Survey ◽  
Storage Site ◽  
Near Surface ◽  
Shallow Subsurface ◽  
Traveltime Tomography ◽  
Reflection Seismic ◽  
Reflection Data

A 3D reflection seismic survey was performed in 2005 at the Ketzin carbon dioxide [Formula: see text] pilot geological-storage site (the [Formula: see text] project) near Berlin, Germany, to image the geological structure of the site to depths of about [Formula: see text]. Because of the acquisition geometry, frequency limitations of the source, and artefacts of the data processing, detailed structures shallower than about [Formula: see text] were unclear. To obtain structural images of the shallow subsurface, we applied 3D traveltime tomography to data near the top of the Ketzin anticline, where faulting is present. Understanding the shallow subsurface structure is important for long-term monitoring aspects of the project after [Formula: see text] has been injected into a saline aquifer at about [Formula: see text] depth. We used a 3D traveltime tomography algorithm based on a combination ofsolving for 3D velocity structure and static corrections in the inversion process to account for artefacts in the velocity structure because of smearing effects from the unconsolidated cover. The resulting velocity model shows low velocities of [Formula: see text] in the uppermost shallow subsurface of the study area. The velocity reaches about [Formula: see text] at a depth of [Formula: see text]. This coincides approximately with the boundary between Quaternary units, which contain the near-surface freshwater reservoir and the Tertiary clay aquitard. Correlation of tomographic images with a similarity attribute slice at [Formula: see text] (about [Formula: see text] depth) indicates that at least one east-west striking fault zone observed in the reflection data might extend into the Tertiary unit. The more detailed images of the shallow subsurface from this study provided valuable information on this potentially risky area.

scholarly journals Cetacean behavioral responses to noise exposure generated by seismic surveys: how to mitigate better?

2016 ◽  
Vol 59 (4) ◽  
Author(s):  
Clara Monaco ◽  
Jesús M. Ibáñez ◽  
Francisco Carrión ◽  
L. Mario Tringali
Keyword(s):  
Noise Exposure ◽  
Behavioral Responses ◽  
Seismic Survey ◽  
Seismic Exploration ◽  
Mitigation Measures ◽  
Seismic Surveys ◽  
Reflection Seismic ◽  
Joint Nature Conservation Committee ◽  
Air Gun ◽  
Southern Mediterranean

<p>Cetaceans use sound in many contexts, such as in social interactions, as well as to forage and to react in dangerous situations. Little information exists to describe how they respond physically and behaviorally to intense and long-term noise levels. Effects on cetaceans from seismic survey activities need to be understood in order to determine detailed acoustic exposure guidelines and to apply appropriated mitigation measures. This study examines direct behavioral responses of cetaceans in the southern Mediterranean Sea during seismic surveys with large airgun arrays (volume up to 5200 ci) used in the TOMO-ETNA active seismic experiment of summer 2014. Wide Angle Seismic and Multi-Channel Seismic surveys had carried out with refraction and reflection seismic methods, producing about 25,800 air-gun shots. Visual monitoring undertaken in the 26 daylights of seismic exploration adopted the protocol of the Joint Nature Conservation Committee. Data recorded were analyzed to examine effects on cetaceans. Sighting rates, distance and orientation from the airguns were compared for different volume categories of the airgun arrays. Results show that cetaceans can be disturbed by seismic survey activities, especially during particularly events. Here we propose many integrated actions to further mitigate this exposure and implications for management.</p>

scholarly journals Thin-skinned thrust-fault tectonics offshore south-west Vietnam

1969 ◽  
Vol 20 ◽  
pp. 99-102
Author(s):  
Stig A. Schack Pedersen ◽  
Lars Ole Boldreel ◽  
Emil Bach Madsen ◽  
Mette Bjerkvig Filtenborg ◽  
Lars Henrik Nielsen
Keyword(s):  
Hanging Wall ◽  
Thrust Fault ◽  
Structural Elements ◽  
Reflection Seismic ◽  
Deep Well ◽  
South West ◽  
Fault Structures ◽  
Fault Deformation ◽  
Sedimentary Succession ◽  
Seismic Sections

In the c. 40 000 km2 large Phu Quoc basin south-west of Vietnam reflection seismic data suggest a thin-skinned thrust-fault complex concealed by Neogene marine sediments (Fig. 1; Fyhn et al. 2010). The deformed sedimentary succession in the complex is of Early Cretaceous age, which is documented by biostratigraphical studies of outcrops and a 500 m deep well on the Phu Quoc island. A model for the thrust-fault deformation suggests that piggy-back basins were formed during displacement along the thrust faults. The translation was 3–8 km from east to west. The model is based on detailed structural analyses of 36 seismic sections that cover the Phu Quoc basin (Fig. 1). The main structural elements in the complex are flats and ramps with hanging-wall anticlines developed above the ramps. The crests of the hanging-wall anticlines occur as remnants of partially eroded structural highs. This paper describes the thin-skinned thrust-fault structures that form the basis for the interpretation of the concealed fold-belt complex in the Phu Quoc basin.

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