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The event aims to be an open space for multidisciplinary and multi-sectoral dialogue aimed at contributing to the definition of a joint vision of “the science we need for the ocean we want” from a gender perspective. We need to focus on solutions based on the science-society binomial. How to improve gender equality and women’s empowerment in ocean science and ocean-related activities, and how to include the gender dimension in the production of knowledge in marine research will be discussed. It will be a space to recognise and make visible the contribution of women to the knowledge and sustainability of the oceans. The conclusions of the event, turned into recommendations, will be provided to key actors in policy making and research. PROGRAMME 15.15 – 15.30: Opening, moderation and closing: Arantza Acha (UN Etxea) and Valentí Sallarès (ICM/CSIC) 15.30 – 16.15: Speakers: Begoña Lasagabaster, Director of the Division for Gender Equality in the Cabinet of the Director-General, UNESCO. Esther Garcés, marine researcher at ICM/CSIC. Farah Obaidullah, Women4Oceans. 16.15 – 16.30: Interactive dialogue

Hoy se ha presentado en el Instituto de Ciencias del Mar de Barcelona del CSIC (ICM-CSIC) la expedición. Durante dos años, TREC, que cuenta con la participación del ICM, tomará muestras en 120 ubicaciones de 21 países europeos, incluyendo los alrededores de Barcelona, ciudad donde hace parada este mes de marzo

El primer llibre de David Farrier, Huellas (Crítica, 2023), ens convida a pensar al voltant de com estem transformant el llenguatge dels elements. En un exercici que combina passat, present i futur, Farrier analitza la genealogia del nostre planeta i ho fa parant atenció a les marees, les roques, les bombolles de gel. El gel és un element central a Germà de gel (L’Altra Editorial, 2015), la novel·la amb la qual Alicia Kopf s’endinsa en les expedicions polars de principis del segle XX. En aquesta conversa, David Farrier i Alicia Kopf rastregen les petjades de la humanitat en els paisatges del nostre planeta, i l’aigua, el gel i la resta d’elements esdevenen un arxiu de la història, una mena de biblioteca que ens ofereix claus de lectura per a les transformacions que han d’arribar. Modera el diàleg Valentí Sallarès, director de l’Institut de Ciències del Mar (ICM) – CSIC

Aquesta jornada, organitzada per l’Ajuntament de Barcelona i la Xarxa BlueNetCat, s'emmarca en la celebració del Dia Internacional de l'Oceà a Barcelona. Té l'objectiu de divulgar la necessitat de protegir, conservar i restaurar els ecosistemes marins urbans a partir de solucions basades en la natura

This hybrid event will be held on January 20, 2023 from 10:00 a.m. to 1:00 p.m. and It is organized in the framework of the European project LeTSGEPs (Leading Towards Sustainable Gender Equality Plans in research performing organizations). In this event will be presented the European framework on gender and research, different perspectives on gender power and its indicators at the structural and cultural level and its reflection in research organisations, and it will be also shared a practice on how to ensure that sex and gender analysis is considered in the design and outputs of research projects. It is also an objective of this event to strengthen the synergies of organizations working to make the integration of the gender dimension into R&I a priority

[EN] In this month's "In Depth" section we talk about the importance of the human footprint on Earth through the analysis of two internationally recognized literary pieces: 'Brother in Ice', by Alícia Kopf, and 'Footprints', by David Farrier, [ES] En el “A Fondo” de este mes hablamos de la importancia de la huella humana sobre la Tierra a través del análisis de dos obras literarias reconocidas a escala internacional: ‘Hermano de hielo’, de Alícia Kopf, y ‘Footprints’ , de David Farrier, [CAT] A l’”A Fons” d’aquest mes parlem de la importància de l’empremta humana sobre la Terra a través de l’anàlisi de dues obres literàries reconegudes a escala internacional: ‘Germà de gel’, de l’Alícia Kopf, i ‘Footprints’, del David Farrier

Muchas personas desconocen que la península ibérica tiene uno de los mayores riesgos de un mega-terremoto y tsunami en todo el Océano Atlántico. En los últimos 9.000 años, el Golfo de Cádiz ha experimentado entre 9 y 14 tsunamis. El último, en 1755, conocido como El gran terremoto de Lisboa, cambió la historia de Europa. ¿Qué pasará cuando llegue el próximo? ¿Qué evidencias tenemos y cómo nos podemos preparar? '¿Preparados para el Tsunami?' es un documental de ciencia, tecnología y medidas de seguridad que, con la participación de especialistas de diferentes centros de investigación, ahonda en las causas de los terremotos y tsunamis, desvela nuevas evidencias sobre la recurrencia con la que ocurren estos fenómenos, da a conocer las medidas de prevención existentes y explora las innovaciones que pueden mantener nuestra seguridad. El film pone sobre la mesa los riesgos actuales a través de hechos históricos y análisis científico, y ofrece consejos prácticos y soluciones basadas en las nuevas tecnologías. Producido por Goat Knight y bajo el guion y la dirección de Erik Martínez-Westley, '¿Preparados para el Tsunami?' cuenta con el testimonio de expertas y expertos de diferentes organismos de investigación como el Instituto de Ciencias del Mar (ICM-CSIC), el Instituto Geológico y Minero de España (IGME-CSIC), el Instituto Español de Oceanografía (IEO-CSIC), el Instituto Geográfico Nacional (IGN), y profesores de las universidades de Cádiz, Málaga, Lisboa y Hawaii, los ayuntamientos de Huelva o Chipiona, ingenieros de Telxius (Telefónica) y la familia de María Belón, supervivientes del tsunami de Tailandia de 2004. El documental, además, está patrocinado por la Universidad de Hawaii y Joint Task Force, Telxius, Telefónica y European Multidisciplinary Seafloor and water column Observatory - European Research Infrastructure Consortium (EMSO-ERIC)

[EN] The southwest Iberia margin hosted the 1755 Lisbon earthquake and ensuing tsunami, one of the most destructive natural events in European history. Here we present a plausible source and mechanism responsible for this event combining geophysical data and numerical tsunami modelling. Our results show that an intra-plate, lithospheric-scale thrust fault located at the Horseshoe Abyssal Plain coincides with the location and focal mechanisms of the largest regional earthquakes and is likely to have suitable dimensions and fault-rock properties to account for the magnitude of the 1755 event. The tsunami simulations with the Horseshoe Abyssal plain Thrust as the source reproduce reported tsunami energy propagation patterns, arrival-times and run up heights more successfully than any other proposed source, [ES] El margen suroeste de Iberia es la región donde ocurrió el terremoto de Lisboa de 1755 y el posterior tsunami, uno de los eventos naturales más destructivos de la historia europea. Aquí presentamos una fuente plausible y un mecanismo responsable de este evento que combina datos geofísicos y modelos numéricos de tsunamis. Nuestros resultados muestran que un cabalgamiento de escala litosférica intraplaca ubicado en la llanura abisal de Horseshoe coincide con la ubicación y los mecanismos focales de los terremotos instrumentales más grandes ocurridos en la región, y es probable que tenga las dimensiones y propiedades de roca de falla adecuadas para explicar la magnitud del evento de 1755. Las simulaciones de tsunami con el Horseshoe Abyssal Plain Thrust como fuente reproducen los patrones de propagación de la energía del tsunami, los tiempos de llegada y las alturas máximas de ola con más éxito que cualquier otra fuente propuesta

Models of continental margins evolution are largely based on incomplete information, much of it built on research that is now >20 years old. Recent developments in parallel computing and novel geophysical approaches provide now the means to obtain a new look at the structure with radically superior resolution seismic models and a mathematically-robust analysis of the data uncertainty, that was formerly difficult, if not unfeasible, to achieve. Thus, we focused on the Newfoundland margin and applied bleeding-edge methodologies to a high-quality dataset acquired in 2000. The SCREECH data includes three primary transects with coincident multichannel seismic reflection data acquired on a 6-km streamer and wide-angle data recorded by short-period OBS and OBH spaced at ~10-20 km. This dataset was processed >15 years ago with now outdated methodologies. This re-processing in an HPC environment provided the high-resolution images that are needed to fulfill the characterization of this margin. In particular, we performed joint inversion of multichannel and wide-angle seismic data, which drastically improved the resolution of the velocity model, which was subsequently used to perform a Pre-Stack Depth Migration of the multichannel data. The higher resolution of these images allows characterization of the different crustal domains of the margin in detail, as well as its tectonic structure. Altogether, these results provide the high-resolution images needed to understand the formation and evolution of the Newfoundland margin. Comparation of these results on the Newfoundland margin with the recent data on the West Iberian margin, acquired during the cruises FRAME (2018) and ATLANTIS (2022) (PI: C. Ranero, streamer data and coincident closely-spaced OBS data), provides a unique opportunity to improve our knowledge on the evolution of the North Atlantic opening

La factura s'ha multiplicat per cinc en centres com l'Institut de Ciències del Mar del CSIC

[...] Tot i l'escepticisme de molts sobre l'efectivitat d'aquesta mena de cimeres, el vicedirector de l'Institut de Ciències del Mar, Valentí Sellarés, creu que a Lisboa s'establiran unes bases similars a les que es van pactar el 2015 a París en relació amb la lluita contra el canvi climàtic: "Jo veig aquesta cimera com una necessitat i una oportunitat equivalent a la cimera del clima de París. Els oceans són un ingredient molt important que regula el clima i una font de recursos que fins ara hem utilitzat de manera irracional, amb els riscos que això comporta."

Conceptual models of magma-poor rifting are strongly based on studies of the nature of the basement in the continent-to-ocean transition of the Iberia Abyssal Plain, and suggest that exhumed mantle abuts extended continental crust. Yet, basement has only been sampled at a few sites, and its regional nature and the transition to seafloor spreading inferred from relatively low-resolution geophysical data are inadequately constrained. This uncertainty has led to a debate about the subcontinental or seafloor-spreading origin of exhumed mantle and the rift-related or oceanic nature of magmatic crust causing the magnetic J anomaly. Different interpretations change the locus of break-up by >100 km and lead to debate of the causative processes. We present the tomographic velocity structure along a 360-km-long seismic profile centered at the J anomaly in the Iberia Abyssal Plain. Rather than delineating an excessive outpouring of magma, the J anomaly occurs over subdued basement. Furthermore, its thin crust shows the characteristic layering of oceanic crust and is juxtaposed to exhumed mantle, marking the onset of magma-starved seafloor spreading, which yields the westward limit of an ~160-km-wide continent–ocean transition zone where continental mantle has been unroofed. This zone is profoundly asymmetric with respect to its conjugate margin, suggesting that the majority of mantle exhumation occurs off Iberia. Because the J anomaly is related to the final break-up and emplacement of oceanic crust, it neither represents synrift magmatism nor defines an isochron, and hence it poorly constrains plate tectonic reconstructions.

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[EN] Last week the Portuguese capital hosted the UN Ocean Conference which, with more than 7,000 attendees, sought to launch a new chapter of global action to protect the big blue, [ES] La semana pasada la capital portuguesa acogió a la UN Ocean Conference que, con más de 7.000 asistentes, buscaba impulsar un nuevo capítulo de acción mundial para proteger el planeta azul, [CAT] La setmana passada la capital portuguesa va acollir la UN Ocean Conference que, amb més de 7.000 assistents, buscava impulsar un nou capítol d’acció mundial per protegir el planeta blau

The purpose of marine seismic experiments is to provide information of the structure and physical properties of the subsurface. The P-wave velocity distribution is the most commonly modelled property, usually by inversion of arrival times or waveform attributes. In wide-angle seismic reflection/refraction (WAS) experiments, arrival times of seismic phases identified in data recorded by ocean bottom seismometers (OBS) are used to image relatively deep structures. Most WAS experiments have relatively low redundancy and produce robust velocity models of limited resolution. The shallow subsurface is also commonly studied with multichannel seismic (MCS) data recorded by towed streamers, a technique that is highly complementary to WAS. In this case, the recording of refractions as first arrivals is limited primarily by the streamer length and by features like water depth and the velocity structure and, in general, most refractions are masked by reflections and noise. However, MCS data of variable quality are available in many regions where no other data exist and previous work has shown that these data can also be used to retrieve velocity models through traveltime and full waveform inversion provided that first arrival information is properly extracted from the record sections. The most widely used tool to extract refractions as first arrivals from MCS recordings is the so-called downward continuation technique, which is designed for redatuming streamer field data to the seafloor. In this new virtual configuration, the early refractions transform to seismic phases that are becoming visible as first arrivals from nearly zero offset, facilitating their identification and use in traveltime tomography. However, there is limited literature, let alone available codes, to be used with the available MCS data sets. This work presents a user-friendly open source HPC software for redatuming 2-D streamer field data to the sea bottom for any seafloor relief. The main ingredient is th

We present a generalized workflow to retrieve high-resolution P-wave velocity ( VP ) models of complex Earth’s subsurface structures from traditional marine near-vertical seismic reflection experiments. These records have typically offsets too short to map refraction phases and lack low-frequency information. The workflow is composed of three steps: 1) downward continuation (DC) of seismic records to the seafloor to recover diving wave information; 2) travel-time tomography (TTT) of first arrivals obtained from DC data, to retrieve a kinematically correct model; and 3) full-waveform inversion (FWI) of the original streamer dataset, starting with the model obtained with TTT and sequentially introducing higher wavenumber details into the model. We show that the TTT allows overcoming the issues associated with the nonlinearity intrinsic to FWI. We also disentangle envelope and phase from the waveform to choose the objective function most suitable for FWI. We assess the accuracy of initial models and predict the quality of the FWI results by quantifying the early arrival cycle skipping between original and simulated data. The efficiency of the workflow is tested with a challenging synthetic target model, containing vertical boundaries with strong velocity contrasts and velocity inversions embedded in a checkerboard-like pattern. We show that workflow steps 1) and 2) provide a TTT model that is not cycle skipped at the frequencies available in most marine seismic experiments and thus allow step 3) FWI to obtain high-resolution VP models of the subsurface using band- and offset-limited field datasets, traditionally collected in marine airgun and streamer acquisitions

[EN] With the advent and gradual acceptance of plate tectonics from the 1960s onwards, it became clear that the Solid Earth is not a fixed and static framework but a dynamic and constantly evolving system that is governed by internal forces impacting on and shaping the surface in multiple ways. The opening and closure of the oceans, the formation of mountain ranges and the occurrence of earthquakes and volcanic eruptions are all a consequence of the constant interaction between tectonic plates. One of the most spectacular and outstanding manifestations of this interaction are earthquakes, which concentrate at the tectonic faults limiting the plates. The largest and most destructive ones occur at the megathrust fault of subduction zones, where the oceanic plates slide below the continental ones at a speed similar to that of fingernail growth. This sliding is not constant but episodic: the friction between the plates makes them couple, accumulating stresses over tens or hundreds of years until they suddenly slip and release the accumulated stresses in seconds or minutes as an earthquake. The amount of slip and its spatial distribution and depth determine the shaking intensity and the resulting ground deformation. […], [ES] A raíz del advenimiento y la gradual aceptación de la tectónica de placas a partir de los años 60 del siglo pasado, se constató que la tierra sólida no es un marco de referencia fijo y estático, sino un sistema dinámico y en constante evolución, gobernado por fuerzas internas que se expresan en superficie de múltiples formas. La apertura y cierre de los océanos, la formación de cordilleras, o los terremotos y volcanes, evidencian la interacción lenta pero constante entre las placas tectónicas. Una de las manifestaciones más espectaculares y notorias de esta interacción son los terremotos, que se concentran principalmente en las fallas tectónicas que limitan las placas. Los más grandes y destructivos tienen lugar en la denominada “falla de mega-cabalgamiento” de las zonas de subducción, donde las placas oceánicas se deslizan bajo las continentales a una velocidad similar a la que crecen las uñas. Este deslizamiento no es constante sino episódico: el rozamiento entre las placas hace que estas se acoplen acumulando esfuerzos durante decenas o centenares de años hasta que resbalan repentinamente liberándolos en segundos o minutos en forma de terremotos. La cantidad de deslizamiento, así como su distribución espacial y la profundidad, determinan la intensidad de las vibraciones y la deformación del terreno asociadas. […], [CAT] Arran de l’adveniment i la gradual acceptació de la tectònica de plaques a partir dels anys 60 del segle passat, es va constatar que la terra sòlida no és un marc de referència fixe i estàtic, sinó un sistema dinàmic i en constant evolució, governat per forces internes que s’expressen en superfície de múltiples formes. L’obertura i tancament dels oceans, la formació de serralades, o els terratrèmols i volcans, evidencien la interacció lenta però constant entre les plaques tectòniques. Una de les manifestacions més espectaculars i notòries d’aquesta interacció són els terratrèmols, que es concentren principalment a les falles tectòniques que limiten les plaques. Els més grans i destructius tenen lloc a la denominada “falla de mega-cavalcament” de les zones de subducció, on les plaques oceàniques llisquen sota les continentals a una velocitat similar a la que creixen les ungles. Aquest lliscament no és constant sinó episòdic: el fregament entre les plaques fa que aquestes s’acoblin acumulant esforços durant desenes o centenars d’anys fins que llisquen sobtadament alliberant-los en segons o minuts en forma de terratrèmols. La quantitat de lliscament, així com la seva distribució espacial i la profunditat determinen la intensitat de les vibracions i la deformació del terreny associades. […]

[EN] The oceans are essential for life on Earth. They sustain ecosystems, stabilize the climatic system and provide resources that make Earth habitable for humankind. However, human activity is causing rapid global changes that affect the ocean’s health and productivity, understood as the resilience to stay within certain boundaries. Global warming, changing weather patterns, sea level rise, ocean acidification and extreme weather events are disrupting the economies of coastal countries and having a profound effect on people’s daily lives. Along with the invasion of anthropic structures on the coastline, marine pollution and overfishing, these environmental stressors alter marine populations, harm ecosystems and threaten biodiversity. Moreover, oceans are the sources of devastating natural hazards that hit the coasts episodically, causing huge human and economic losses. […], [ES] Los océanos son fundamentales para la vida en la Tierra. Ellos sostienen los ecosistemas, estabilizan el sistema climático y proporcionan los recursos que hacen de la Tierra un planeta habitable para la humanidad. Sin embargo, la actividad humana está provocando rápidos cambios globales que afectan la salud de los océanos, entendida como su resiliencia para mantenerse dentro de ciertos límites. El calentamiento global, las fluctuaciones climáticas, el aumento del nivel del mar, la acidificación de los océanos y los eventos climáticos extremos perturban las economías de los países costeros y afectan la vida cotidiana de sus habitantes. A estos factores de estrés ambiental se le añaden la invasión de estructuras antrópicas en el litoral, la contaminación marina y la sobrepesca, que alteran las poblaciones marinas, dañan los ecosistemas y amenazan la biodiversidad. Además, los océanos están sujetos a diversos riesgos naturales, que golpean episódicamente las costas causando enormes pérdidas humanas y económicas. […], [CAT] Els oceans són fonamentals per a la vida a la Terra. Ells sostenen els ecosistemes, estabilitzen el sistema climàtic i proporcionen els recursos que fan que la Terra sigui habitable per a la humanitat. Tanmateix, l’activitat humana està provocant ràpids canvis globals que afecten la salut dels oceans, entesa com a resiliència per a mantenir-se dins d’uns certs límits. L’escalfament global, les alteracions dels patrons climàtics, la pujada del nivell del mar, l’acidificació dels oceans i els fenòmens meteorològics puntuals i extrems, pertorben les economies dels països costaners i afecten la vida quotidiana dels seus habitants. A aquests factors d’estrès ambiental se li afegeixen la invasió d’estructures antròpiques en el litoral, la contaminació marina i la sobrepesca, que alteren les poblacions marines, perjudiquen el funcionament dels ecosistemes i amenacen la biodiversitat. A més, els oceans estan subjectes a diversos riscos naturals, que colpegen episòdicament les costes causant enormes pèrdues humanes i econòmiques. […]

A new code for anisotropic traveltime tomography is presented. We describe the equations governing the anisotropic ray propagation algorithm and the modified inversion solver. This code can provide better understanding of the Earth's subsurface in the rather common geological contexts in which seismic velocity displays a weak dependency on the polar angle of ray propagation. We study the sensitivity of two medium parametrizations and compare four inversion strategies on a canonical model. The synthetic data sets for all these tests can be found in this repository directory

Large earthquake ruptures propagating up to areas close to subduction trenches are infrequent, but when they occur, they heavily displace the ocean seafloor originating destructive tsunamis. The current paradigm is that the large seafloor deformation is caused by local factors reducing friction and increasing megathrust fault slip, or prompting the activation of ancillary faults or energy sources. As alternative to site-specific models, it has been proposed that large shallow slip could result from depth-dependent rock rigidity variations. To confront both hypotheses, here, we map elastic rock properties across the rupture zone of the M S 7.0- M W 7.7 1992 Nicaragua tsunami earthquake to estimate a property-compatible finite fault solution. The obtained self-consistent model accounts for trenchward increasing slip, constrains stress drop, and explains key tsunami earthquake characteristics such as long duration, high-frequency depletion, and magnitude discrepancy. The confirmation that these characteristics are all intrinsic attributes of shallow rupture opens new possibilities to improve tsunami hazard assessment.

Un estudio liderado por el Institut de Ciències del Mar (ICM-CSIC) de Barcelona ha logrado revelar el mecanismo físico que produce los llamados "terremotos de tsunami", sismos de magnitud moderada que ocasionan tsunamis destructivos, así como el origen de sus características y su causa. Según ha informado la entidad, el descubrimiento, publicado en la revista Science Advances, permite ahondar en el conocimiento de esta clase particular de sismos que, a pesar de su magnitud moderada, provocan tsunamis destructivos porque se suelen percibir débilmente y, por tanto, golpean la costa inesperadamente

Earthquakes rupturing up to close to subduction trenches have produced some of the largest tsunamis in history. Models indicate that the generation of these tsunamis require extraordinarily large near-trench sea-bottom displacement, but the underlying causes are disputed. They have been attributed to a wealth of factors prompting large shallow slip at the low-angle megathrust fault, the activation of steeper faults requiring smaller slip, or the triggering of ancillary energy sources. Although the postulated mechanisms are manifold, all of them coincide on the fact that the proposed causes and constraining factors are not universal but site-specific. As alternative to this local view, it has recently been proposed that the large near-trench slip could result from systematic upper-plate rock rigidity variations observed in worldwide subduction zones. Here we use a set of available controlled-source seismic data in the Middle America margin to obtain a model of upper-plate elastic rock properties across the rupture zone of the Ms7.0-Mw7.7 1992 Nicaragua tsunami earthquake. In combination with seismological data, our model shows that not only the required large shallow slip to generate the tsunami despite the moderate magnitude, but also the observed slow rupture propagation, long duration, high-frequency depletion, and magnitude discrepancy of this event, are all intrinsic physical attributes of near-trench rupture. The existence of a causal link between shallow slip and seismic record characteristics opens up new possibilities for tsunami early warning

Oceans are no longer inaccessible places for data acquisition. High-throughput technological advances applied to marine sciences (from genes to global current patterns) are generating Big Data sets at unprecedented rates. How to manage, store, analyse, useand transform this data deluge into knowledge is now a fundamental challenge for ocean sciences. Artificial Intelligence and Machine Learning are the most promising and exciting approaches addressing this challenge. These technologies are directly applicable to many data analysis problems and major challenges in the study of the ocean microbiome, ocean observation and forecasting, animal biology, ecology and conservation, resource management, and marine geosciences. We are only at the beginning of an era when machines are able to solve complex tasks that, until today, have required human expertise. We envision that the combination of ocean Big Data and Artificial Intelligence will provide the means for ground-breaking advances in our understanding of ocean functioning.

In this PhD work, I carried out a geophysical and geological study of two classical examples of rifted continental margins: the Gulf of Lions, located in the Western Mediterranean, and the Tagus Abyssal Plain, located in the West Iberia margin. Despite the numerous previous studies performed in these two margins, there is an open debate on their crustal structure and on the processes that led to their formation. My study aims to 1) determining the nature of rocks forming the main geological domains of the basin based on a new methodological approach, 2) defining the tectonic structure of the basement and 3) placing constrains and discussing the kinematics and tectonic and magmatic mechanisms involved in the formation of these basins. To study the Gulf of Lions and Ligurian basin, I used a geophysical data set acquired during the SARDINIA-2006 survey. It was conducted on board the French R/V L’Atalante, by the L'Institut Français de Recherche pour l'Exploitation de la Mer (Ifremer) (France). In particular, I used seismic records along three spatially consecutive Multi-Channel Seismic (MCS) lines and a collocated Wide-Angle Seismic (WAS) profile recorded by a set of Ocean Bottom Seismometers (OBS) during the shooting of the MCS lines. Altogether, these lines cover a 467-km-long seismic transect that runs NW-SE across the Gulf of Lions until the central part of the Liguro-Provençal basin. [...]

Un estudio del Instituto de Ciencias del Mar (ICM-CSIC) de Barcelona ha permitido identificar una falla inversa como fuente tectónica y mecanismo responsable del "grave" terremoto de Lisboa (Portugal) de 1755, que tuvo una magnitud de 8,5

Un estudi liderat per l'Institut de Ciències del Mar (ICM-CSIC) de Barcelona ha aconseguit revelar el mecanisme físic que produeix els anomenats «terratrèmols de tsunami», sismes de magnitud moderada que produeixen tsunamis destructius, així com l'origen de les seves característiques i la seva causa

Proteger barreras naturales como arrecifes de coral, manglares y bosques costeros «reduce la vulnerabilidad y los daños catastróficos» de las poblaciones ante inundaciones y tsunamis, han insistido a Efe varios expertos con motivo, hoy, del Día Mundial de Concienciación sobre los Tsunamis

It has been recently proposed that the depth-varying rupture properties of megathrust earthquakes can be explained by the depth distribution of elastic properties of the rocks overlying the megathrust fault. Here we demonstrate that such relationship is mechanically viable by using 3D dynamic rupture simulations. We compare results from two subduction zone scenarios with different depth-distribution of elastic properties to explore the influence of realistic upper-plate elasticity on rupture characteristics such as slip, rupture duration, and frequency content. The first scenario has a homogeneous distribution of elastic properties, with values of Vp, Vs, and density typical of rocks overlying the megathrust fault at 25 km depth. The second scenario includes the typical depth distribution of elastic properties overlying the megathrust fault inferred from worldwide tomographic models of the upper plate. For both scenarios, we simulate three cases with ruptures confined to the shallow domain (0-5 km depth), transitional domain (5-10 km depth), and regular domain (10-25 km depth), respectively. We assume the same friction properties for both scenarios. Results show that the realistic distribution of elastic properties accounts for increasing slip and decreasing high frequency content trenchwards, and that slip may be 8 times larger and corner frequency 2 times lower in the shallow domain than in the regular domain. Rupture times along depth shows that the rupture through a realistic elastic model may be 2.5-3 times slower in the shallow domain than in the regular domain. Depth-variations of slip, frequency content, and rupture time quantitatively agree with previous predictions, confirming that depletion of high frequency content and slow rupture are inherent of ruptures propagating through the shallow domain, where elastic properties variations drop more rapidly than in the regular and transitional domains. Depth-dependent elastic properties also affect the dynamics o

The SW Iberian Margin has a complex tectonic setting and crustal structure derived from a succession of rift events related to the opening of North Atlantic and Neotethys from the Mesozoic to the Lower Cretaceous, and to the subsequent convergence between Nubian and Eurasian plates from Lower Oligocene to present day. Neogene plate convergence led to the reactivation of pre-existing extensional faults originated during the Mesozoic rifting in a combination of thrust and strike-slip systems. Despite a slow convergence rate, these faults now represent a major regional seismological and tsunamigenic hazard, as demonstrated by the devastating 1755 Lisbon earthquake of M>8.5 and the ensuing tsunami. Thus, unveiling the lithospheric structure along the SW Iberian Margin is not only important to understand the different stages of rifting and compression, but also to characterize the distribution of major lithospheric-scale boundaries, currently active and potentially capable of generating great, destructive tsunamigenic earthquakes. To this end, we use here a spatially coincident wide-angle seismic (WAS) and multichannel seismic (MCS) data set collected along a NW-SE ~320 km transect SW of São Vicente cape during the FRAME survey in 2018. WAS data were recorded by 24 ocean bottom seismometers and hydrophones (OBS/H) while the MCS data were recorded by a 6 km long, 480 channel streamer. From NW to SE, the transect runs from the Tagus Abyssal plain to the westernmost extension of the Gulf of Cadiz across four major thrust faults, namely, the Tagus Abyssal Plain fault, Marquês de Pombal fault, São Vicente fault, and Horseshoe fault. We applied joint refraction and reflection travel-time tomography (TTT) using a combination of arrival times identified at both WAS and MCS recordings to invert for the 2D P-wave velocity (Vp) structure of the crust and uppermost mantle, as well as the geometry of the main structural boundaries identified as seismic reflectors: the top of the acou

Megathrust earthquakes are strongly influenced by the elastic properties of rocks surrounding the fault. In contrast to friction, these properties can be derived in situ from geophysical measurements along the seismogenic zone. However, they are often overestimated in numerical simulations, particularly in the shallow megathrust. Here we explore the influence that realistic depth-varying upper-plate elastic properties along the megathrust have on earthquake rupture dynamics and tsunamigenesis using 3D dynamic rupture and tsunami simulations. We compare results from three subduction zone scenarios with homogeneous and heterogeneous elastic media, and bimaterial fault. Elastic properties in the heterogeneous model follow a realistic depth-distribution derived from controlled-source tomography models of subduction zones. We assume the same friction properties for all scenarios. Simulations in the heterogeneous and homogeneous models show that rigidity depth variations explain the depth-varying behavior of slip, slip rate, frequency content, and rupture time. The depth-varying behavior of slip, frequency content, and rupture duration quantitatively agree with previous predictions based on worldwide data compilations, explaining the main depth-dependent traits of tsunami earthquakes and large shallow megathrust earthquakes. Large slip, slow rupture and slip rate amplification in bimaterial simulations are largely controlled by elastic rock properties of the most compliant side of the fault, which in subduction zones is the upper plate. Large shallow slip and trenchward increasing upper-plate compliance of the heterogeneous model lead to the largest co-seismic seafloor deformation and tsunami amplitude. This highlights the importance of considering realistic upper-plate rigidity variations to properly assess the tsunamigenic potential of megathrust earthquakes