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| Registros recuperados: 15 | |
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| Kolinsky, Petr; Bokelmann, Goetz; Hetenyi, Gyorgy; Abreu, Rafael; Allegretti, Ivo; Apoloner, Maria-theresia; Aubert, Coralie; Besancon, Simon; Bes De Berc, Maxime; Bokel-mann, Gotz; Brunel, Didier; Capello, Marco; Carman, Martina; Cavaliere, Adriano; Cheze, Jerome; Chiarabba, Claudio; Clinton, John; Cougoulat, Glenn; Crawford, Wayne C.; Cristiano, Luigia; Czifra, Tibor; D'Alema, Ezio; Danesi, Stefania; Daniel, Romuald; Dannowski, Anke; Dasovic, Iva; Deschamps, Anne; Dessa, Jean-xavier; Doubre, Cecile; Egdorf, Sven; Fiket, Tomislav; Fischer, Kasper; Friederich, Wolfgang; Fuchs, Florian; Funke, Sigward; Giardini, Domenico; Govoni, Aladino; Graczer, Zoltan; Groschl, Gidera; Heimers, Stefan; Heit, Ben; Herak, Davorka; Herak, Marijan; Huber, Johann; Jaric, Dejan; Jedlicka, Petr; Jia, Yan; Jund, Helene; Kissling, Edi; Klingen, Stefan; Klotz, Bernhard; Kolinsky, Petr; Kopp, Heidrun; Korn, Michael; Kotek, Josef; Kuhne, Lothar; Kuk, Kreso; Lange, Dietrich; Loos, Jurgen; Lovati, Sara; Malengros, Deny; Margheriti, Lucia; Maron, Christophe; Martin, Xavier; Massa, Marco; Mazzarini, Francesco; Meier, Thomas; Metral, Laurent; Molinari, Irene; Moretti, Milena; Nardi, Anna; Pahor, Jurij; Paul, Anne; Pequegnat, Catherine; Petersen, Daniel; Pesaresi, Damiano; Piccinini, Davide; Piromallo, Claudia; Plenefisch, Thomas; Plomerova, Jaroslava; Pondrelli, Silvia; Prevolnik, Snjezan; Racine, Roman; Regnier, Marc; Reiss, Miriam; Ritter, Joachim; Rumpker, Georg; Salimbeni, Simone; Santulin, Marco; Scherer, Werner; Schippkus, Sven; Schulte-kortnack, Detlef; Sipka, Vesna; Solarino, Stefano; Spallarossa, Daniele; Spieker, Kathrin; Stipcevic, Josip; Strollo, Angelo; Sule, Balint; Szanyi, Gyongyver; Szucs, Eszter; Thomas, Christine; Thorwart, Martin; Tilmann, Frederik; Ueding, Stefan; Vallocchia, Massimiliano; Vecsey, Ludek; Voigt, Rene; Wassermann, Joachim; Weber, Zoltan; Weidle, Christian; Wesztergom, Viktor; Weyland, Gauthier; Wiemer, Stefan; Wolf, Felix; Wolyniec, David; Zieke, Thomas; Zivcic, Mladen; Zlebcikova, Helena. |
| The dense AlpArray network allows studying seismic wave propagation with high spatial resolution. Here we introduce an array approach to measure arrival angles of teleseismic Rayleigh waves. The approach combines the advantages of phase correlation as in the two-station method with array beamforming to obtain the phase-velocity vector. 20 earthquakes from the first two years of the AlpArray project are selected, and spatial patterns of arrival-angle deviations across the AlpArray are shown in maps, depending on period and earthquake location. The cause of these intriguing spatial patterns is discussed. A simple wave-propagation modelling example using an isolated anomaly and a Gaussian beam solution suggests that much of the complexity can be explained as... |
| Tipo: Text |
Palavras-chave: Structure of the Earth; Europe; Time-series analysis; Surface waves and free oscillations; Wave propagation; Wave scattering and diffraction. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00690/80172/83241.pdf |
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| De Carlo, M; Ardhuin, Fabrice; Le Pichon, A. |
| Between 0.1 and 0.5 Hz, infrasound signals recorded in the atmosphere are dominated by ocean-generated noise called microbaroms. Microbaroms propagate through the atmosphere over thousands of kilometers due to low absorption and efficient ducting between the ground and the stratopause. Different theoretical models have been developed to characterize the source of microbaroms, all based on the second-order non-linear interaction of ocean waves. While early theories considered an infinite ocean depth and a source radiation depending on the acoustic wave elevation angle, other works have approximated the radiation pattern as a monopole, and found a considerable effect of the water depth. This paper reviews these models and extends the previous theories to the... |
| Tipo: Text |
Palavras-chave: Interface waves; Wave propagation; Infrasound. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00602/71378/69827.pdf |
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| Ker, Stephan; Le Gonidec, Y.; Marsset, Bruno; Westbrook, Graham; Gibert, D.; Minshull, T. A.. |
| In the context of seismic imaging of gas/gas-hydrate systems, the fine-scale structure of subseabed gas-related reflections is assessed by taking advantage of the source signature of the deep-towed high-resolution SYSIF seismic device. We demonstrate the value of an original wavelet-based method and associated multiscale seismic attributes, applied to seismic data recently acquired on the western margin of the Arctic archipelago of Svalbard. From analysis in the wavelet domain, we recognize two types of gas-related reflections associated with submetre-scale distribution of gas. We identify a thin gas-charged layer associated with an apparent normal polarity reflection, and we detect gas patches associated with a reverse-polarity bright spot with... |
| Tipo: Text |
Palavras-chave: Wavelet transform; Gas and hydrate systems; Wave propagation; Acoustic properties; Arctic region. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00175/28602/27019.pdf |
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| Le Gall, Yves; Origne, Laurent; Scalabrin, Carla; Morizur, Yvon. |
| Acoustic deterrent devices could be an appealing solution to tackle accidental cetacean by-catches in pelagic trawls or in fishing net gears. The bibliographical data on two species (Harbour porpoise and bottlenosed dolphin) have been analyzed in terms of audiogram, discomfort noise level that could lead to behavioural changes, sensory fatigue, and threshold for permanent hearing injuries. It is possible, on the basis of the above data, to characterize an efficient annoyance sound threshold which is not harmful to the species to be protected. Taking into account the properties of the sound waves propagation in the marine environment and according to the required range, the minimal amplitude of the repulsive sound to emit is proposed. Accordingly, the... |
| Tipo: Text |
Palavras-chave: Wave propagation; Behaviour; Audiogram; Capture; Cetacean; In fishing net gear; Pelagic trawl; Acoustic deterrent; Propagation onde; Comportement; Audiogramme; Capture; Cétacé; Filet; Pêche artisanale; Chalutage pélagique; Répulsif acoustique. |
| Ano: 2004 |
URL: http://archimer.ifremer.fr/doc/2004/acte-1124.pdf |
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| Tary, Jean-baptiste; Geli, Louis; Guennou, Claude; Henry, Pierre; Sultan, Nabil; Cagatay, N.; Vidal, V.. |
| Different types of 4-component ocean bottom seismometers (OBS) were deployed for variable durations ranging from 1 week to about 4 months in 2007, over soft sediments covering the seafloor of the Tekirdag Basin (western part of the Sea of Marmara, Turkey). Non-seismic microevents were recorded by the geophones, but generally not by the hydrophones, except when the hydrophone is located less than a few tens of centimetres above the seafloor. The microevents are characterized by short durations of less than 0.8 s, by frequencies ranging between 4 and 30 Hz, and by highly variable amplitudes. In addition, no correlation between OBSs was observed, except for two OBSs, located 10 m apart. Interestingly, a swarm of similar to 400 very similar microevents (based... |
| Tipo: Text |
Palavras-chave: Time series analysis; Gas and hydrate systems; Body waves; Interface waves; Seismic attenuation; Wave propagation. |
| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00089/20012/17825.pdf |
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| Stutzmann, E.; Ardhuin, Fabrice; Schimmel, M.; Mangeney, A.; Patau, G.. |
| The strongest seismic noise, called secondary microseisms, is generated by ocean wave interactions and we model this noise using the theory of Longuet-Higgins generalized to random ocean gravity waves. Noise sources are computed with an ocean wave model that takes into account coastal reflections. Variations of the source locations are consistent with seasonal variations of seismic noise spectra. Noise spectra are modelled over many years for stations representative of various environments such as continent, island and polar area to constrain, for each environment, the parameters involved in the modelling. For each station, we quantify the trade-off between ocean wave coastal reflection and seismic wave attenuation that both affect the amplitude of the... |
| Tipo: Text |
Palavras-chave: Surface waves and free oscillations; Theoretical seismology; Wave propagation. |
| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00107/21839/19436.pdf |
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| Ker, Stephan; Le Gonidec, Y.; Gibert, D.. |
| In the context of multiscale seismic analysis of complex reflectors, that takes benefit from broad-band frequency range considerations, we perform a wavelet-based method to merge multiresolution seismic sources based on generalized Lévy-alpha stable functions. The frequency bandwidth limitation of individual seismic sources induces distortions in wavelet responses (WRs), and we show that Gaussian fractional derivative functions are optimal wavelets to fully correct for these distortions in the merged frequency range. The efficiency of the method is also based on a new wavelet parametrization, that is the breadth of the wavelet, where the dominant dilation is adapted to the wavelet formalism. As a first demonstration to merge multiresolution seismic... |
| Tipo: Text |
Palavras-chave: Wavelet transform; Wave propagation; Acoustic properties. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00157/26824/24935.pdf |
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| Ker, Stephan; Le Gonidec, Yves; Gibert, D.; Marsset, Bruno. |
| We propose a wavelet-based method to characterize acoustic impedance discontinuities from a multiscale analysis of seismic reflected waves. Our approach relies on the analysis of ridge functions which contain most of the information of the wavelet transform in a sparse support. This method falls in the framework of the wavelet response (WR) introduced by Le Gonidec et al. which analyses the impedance multiscale behaviour by propagating dilated wavelets into the medium. We further extend the WR by considering its application to broad-band seismic data. We take into account the bandpass filter effect related to the limited frequency range of the seismic source. We apply the method to a deep-water seismic experiment performed in 2008 during the ERIG3D cruise... |
| Tipo: Text |
Palavras-chave: Wavelet transform; Seismic attenuation; Wave propagation; Acoustic properties. |
| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00049/15994/13449.pdf |
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| Ker, Stephan; Le Gonidec, Yves; Gibert, Dominique. |
| A wavelet-based method was presented in a previous work to introduce multiscale seismic attributes for high-resolution seismic data. Because of the limited frequency bandwidth of the seismic source, we observed distortions in the seismic attributes based on the wavelet response of the subsurface discontinuities (Le Gonidec et al.). In this paper, we go further in the seismic source-correction by considering L´evy alpha-stable distributions introduced in the formalism of the continuous wavelet transform (CWT). The wavelets are Gaussian derivative functions (GDF), characterized by a derivative order. We show that a high-resolution seismic source, after a classical signature processing, can be taken into account with a GDF. We demonstrate that in the... |
| Tipo: Text |
Palavras-chave: Wavelet transform; Wave propagation; Acoustic properties. |
| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00090/20155/17828.pdf |
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| Trabattoni, A; Barruol, G; Dreo, R; Boudraa, A O; Fontaine, F R. |
| Breakthroughs in understanding the structure and dynamics of our planet will strongly depend upon instrumenting deep oceans. Progress has been made these last decades in ocean-bottom seismic observations, but ocean-bottom seismometer (OBS) temporary deployments are still challenging and face set-up limitations. Launched from oceanographic vessels, OBSs fall freely and may slightly drift laterally, dragged by currents. Therefore, their actual orientation and location on the landing sites are hard to assess precisely. Numerous techniques have been developed to retrieve this key information, but most of them are costly, time-consuming or inaccurate. In this work, we show how ship noise can be used as an acoustic source of opportunity to retrieve both the... |
| Tipo: Text |
Palavras-chave: Seismic instruments; Seismic noise; Wave propagation; Body waves; Statistical methods; Acoustic properties. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00593/70463/68591.pdf |
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| Lomax, A. |
| In this paper, we examine an efficient, practical method to calculate approximate, finite-frequency waveforms for the early signals from a point source in 3-D acoustic media with smoothly varying velocity and constant density. In analogy to the use of Feynman path integrals in quantum physics, we obtain an approximate waveform solution for the scalar wave equation by a Monte Carlo summation of elementary signals over a representative sample of all possible paths between a source and observation point. The elementary signal is formed from the convolution of the source time function with a time derivative of the Green's function for the homogeneous problem. For each path, this elementary signal is summed into a time series at a travel time obtained from an... |
| Tipo: Text |
Palavras-chave: Inversion; Lateral heterogeneity; Synthetic waveforms; Wave equation; Wave propagation. |
| Ano: 1999 |
URL: https://archimer.ifremer.fr/doc/00466/57771/60028.pdf |
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| Farra, V.; Stutzmann, Eleonore; Gualtieri, Lucia; Schimmel, M.; Ardhuin, Fabrice. |
| Secondary microseism sources are pressure fluctuations close to the ocean surface. They generate acoustic P-waves that propagate in water down to the ocean bottom where they are partly reflected, and partly transmitted into the crust to continue their propagation through the Earth. We present the theory for computing the displacement power spectral density of secondary microseism P-waves recorded by receivers in the far field. In the frequency domain, the P-wave displacement can be modeled as the product of (1) the pressure source, (2) the source site effect that accounts for the constructive interference of multiply reflected P-waves in the ocean, (3) the propagation from the ocean bottom to the stations, (4) the receiver site effect. Secondary microseism... |
| Tipo: Text |
Palavras-chave: Seismic interferometry; Body waves; Seismic noise; Wave propagation. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00344/45509/45063.pdf |
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| Monbaliu, J.; Padilla-Hernandez, R.; Hargreaves, J.C.; Carretero Albiach, J.C.; Luo, W.; Sclavo, M.; Günther, H.. |
| New features have been added and several necessary changes have been made to the standard WAM-cycle4 (WAMC4) model code for it to run efficiently when applied to shallow water regions. The restriction of having a source term integration time step smaller than or equal to the propagation time step was relaxed, considerably reducing the computational time needed. An additional reduction in computing time and an increase in accuracy were obtained by introducing a split-frequency time step. There is now a choice of using the octant or quadrant coordinate system for the propagation of the wave energy. The source term integration and, more particularly, the use of a limiter on the energy growth, were studied. For the evaluation of the energy decay in shallow... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Breaking waves; Coastal engineering; Mathematical models; Shallow water; Wave predicting; Wave propagation. |
| Ano: 2000 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=6924 |
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| Ioualalen, Mansour; Ratzov, G.; Collot, Jean-yves; Sanclemente, E.. |
| P>Shelf promontories exhibit very specific bathymetric features with regards to tsunamis. Because of their submerged cape morphology, a potential tsunami generated seawards of the promontory will exhibit a specific mode of propagation and coastal impact. To identify this peculiar tsunami signature, the Atacames Promontory, Ecuador, was chosen as a case study (another example is the shelf of the Nile delta, Egypt). The area is tectonically very active, hosts earthquakes among the most powerful recorded, as well as areas of slope instabilities that have triggered significant submarine landslides in the past (several cubic kilometres of volume). Both types of events are likely to be tsunamigenic. To examine the tsunami behaviour at the coastal area of the... |
| Tipo: Text |
Palavras-chave: Tsunamis; Site effects; Wave propagation; Submarine landslides; South America. |
| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00200/31101/29509.pdf |
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| Registros recuperados: 15 | |
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