@conference {Tejero2014,
	title = {{Comparison of objective functionals in seismic full waveform inversion}},
	booktitle = {76th European Association of Geoscientists and Engineers Conference and Exhibition 2014: Experience the Energy - Incorporating SPE EUROPEC 2014},
	year = {2014},
	pages = {2819{\textendash}2823},
	publisher = {EAGE Publishing BV},
	organization = {EAGE Publishing BV},
	abstract = {The FWI method is a powerful tool that allows one to obtain high-resolution information from the subsurface. However, the method is highly non-linear as in the convergence to the solution it might get trapped in local-minima. Among other techniques, it becomes crucial a suitable choice of the objective function. We have selected five objective functions to perform a comparative study under a common 2Dacoustic FWI scheme: the L2-nom, cross-correlation travel time (CCTT), non-integration-method (NIM), envelope and phase objective functions. We test with a 2D-canonical model the susceptibility of the functions to the initial model perturbations. To complete de study with a more realistic synthetic example we test the functions with the Marmousi model. The L2-norm and phase objective functions give the highest resolution images and the CCTT, NIM and envelope objective functions lead to smooth models. However in realistic initial conditions, L2 and phase misfits fail in recovering the velocity model in contrast to the CCTT, NIM and envelope functions that maintain a more consistent behavior.},
	isbn = {9781632666949},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84907396478\&partnerID=tZOtx3y1},
	author = {Tejero, C. E Jimenez and Dagnino, D. and Sallar{\`e}s, V. and Ranero, C.}
}
@article {Dagnino2014,
	title = {{Scale- and parameter-adaptive model-based gradient pre-conditioner for elastic full-waveform inversion}},
	journal = {Geophysical Journal International},
	volume = {198},
	number = {2},
	year = {2014},
	month = {jun},
	pages = {1130{\textendash}1142},
	publisher = {Oxford University Press},
	abstract = {We present a scale- and parameter-adaptive method to pre-condition the gradient of the parameters to be inverted in time-domain 2-D elastic full-waveform inversion (FWI). The proposed technique, which relies on a change of variables of the model parameters, allows to balance the value of the gradient of the Lam{\'e} parameters and density throughout the model in each step of the multiscale inversion. The main difference compared to existing gradient pre-conditioners is that the variables are automatically selected based on a least squares minimization criteria of the gradient weight, which corresponds to the product of the gradient by a power of the parameter to be inverted. Based on numerical tests made with (1) a modified version of the Marmousi-2 model, and (2) a high-velocity and density local anomaly model, we illustrate that the value of the power helps to balance the gradient throughout the model. In addition, we show that a particular value exists for each parameter that optimizes the inversion results in terms of accuracy and efficiency. For the two models, the optimal power is \~{}2.0-2.5 and and \~{}1.5 for the first and second Lam{\'e} parameters, respectively; and between 3 and 6, depending on the inverted frequency, for density. These power values provide the fastest and most accurate inversion results for the three parameters in the framework of multiscale and multishooting FWI using three different optimization schemes. {\textcopyright} The Authors 2014. Published by Oxford University Press on behalf of The Royal Astronomical Society.},
	keywords = {Computational seismology, Inverse theory, Numerical approximations and analysis, Seismic tomography},
	issn = {0956-540X},
	doi = {10.1093/gji/ggu175},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84903949166\&partnerID=tZOtx3y1},
	author = {Dagnino, D. and Sallar{\`e}s, V. and Ranero, C. R.}
}
@article {Prada2014,
	title = {{Seismic structure of the Central Tyrrhenian basin: Geophysical constraints on the nature of the main crustal domains}},
	journal = {Journal of Geophysical Research: Solid Earth},
	volume = {119},
	number = {1},
	year = {2014},
	pages = {52{\textendash}70},
	publisher = {Blackwell Publishing Ltd},
	abstract = {In this work we investigate the crustal and tectonic structures of the Central Tyrrhenian back-arc basin combining refraction and wide-angle reflection seismic (WAS), gravity, and multichannel seismic (MCS) reflection data, acquired during the MEDOC (MEDiterr{\'a}neo OCcidental)-2010 survey along a transect crossing the entire basin from Sardinia to Campania at 40{\textdegree}N. The results presented include a \~{}450 km long 2-D P wave velocity model, obtained by the traveltime inversion of the WAS data, a coincident density model, and a MCS poststack time-migrated profile. We interpret three basement domains with different petrological affinity along the transect based on the comparison of velocity and velocity-derived density models with existing compilations for continental crust, oceanic crust, and exhumed mantle. The first domain includes the continental crust of Sardinia and the conjugate Campania margin. In the Sardinia margin, extension has thinned the crust from \~{}20 km under the coastline to \~{}13 km \~{}60 km seaward. Similarly, the Campania margin is also affected by strong extensional deformation. The second domain, under the Cornaglia Terrace and its conjugate Campania Terrace, appears to be oceanic in nature. However, it shows differences with respect to the reference Atlantic oceanic crust and agrees with that generated in back-arc oceanic settings. The velocities-depth relationships and lack of Moho reflections in seismic records of the third domain (i.e., the Magnaghi and Vavilov basins) support a basement fundamentally made of mantle rocks. The large seamounts of the third domain (e.g., Vavilov) are underlain by 10-20 km wide, relatively low-velocity anomalies interpreted as magmatic bodies locally intruding the mantle. {\textcopyright}2013. American Geophysical Union. All Rights Reserved.},
	keywords = {back-arc crust, exhumed mantle, Rifting, traveltime tomography, Tyrrhenian basin, wide-angle seismics},
	issn = {21699313},
	doi = {10.1002/2013JB010527},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84896740908\&partnerID=tZOtx3y1},
	author = {Prada, M. and Sallar{\`e}s, V. and Ranero, C. R. and Vendrell, M. G. and Grevemeyer, I. and Zitellini, N. and de Franco, R.}
}
@article {Bornstein2013,
	title = {{Direct temperature and salinity acoustic full waveform inversion}},
	journal = {Geophysical Research Letters},
	volume = {40},
	number = {16},
	year = {2013},
	month = {aug},
	pages = {4344{\textendash}4348},
	abstract = {Recent work has shown that Full Waveform Inversion could be suitable to extract physical properties such as sound speed (c), density ($\rho$), temperature (T), and salinity (S) from the weak impedance contrasts associated with the ocean{\textquoteright}s thermohaline fine structure.The seismic inversion approaches proposed so far are based on the iterative inversion of c from multichannel seismic data, while the rest of parameters (T,S, and $\rho$) are determined in a second step using two equations of state and a local T-S empirical relationship. In this work, we present an alternative to this approach. Using 1-D synthetic seismic data, we demonstrate that the direct full waveform inversion of T and S using adjoint methods is feasible without the use of any local T-S relationship and that the models of physical properties obtained with this approach are far more accurate than those inferred from c. Key Points T and S can be inverted simultaneously from ocean acoustic data using FWI Local T-S empirical relationships are not required for the inversion Our T and S results have a potential density error of 0.01 kg/m3. {\textcopyright} 2013. American Geophysical Union. All Rights Reserved.},
	keywords = {acoustic oceanography, adjoint method, full waveform inversion, thermohaline fine structure},
	issn = {00948276},
	doi = {10.1002/grl.50844},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84882307211\&partnerID=tZOtx3y1},
	author = {Bornstein, G. and Biescas, B. and Sallar{\`e}s, V. and Mojica, J. F.}
}
@article {Moeller2013,
	title = {{Early-stage rifting of the northern Tyrrhenian Sea Basin: Results from a combined wide-angle and multichannel seismic study}},
	journal = {Geochemistry, Geophysics, Geosystems},
	volume = {14},
	number = {8},
	year = {2013},
	month = {aug},
	pages = {3032{\textendash}3052},
	abstract = {Extension of the continental lithosphere leads to the formation of rift basins and ultimately may create passive continental margins. The mechanisms that operate during the early stage of crustal extension are still intensely debated. We present the results from coincident multichannel seismic and wide-angle seismic profiles that transect across the northern Tyrrhenian Sea Basin. The profiles cross the Corsica Basin (France) to the Latium Margin (Italy) where the early-rift stage of the basin is well preserved. We found two domains, each with a distinct tectonic style, heat flow and crustal thickness. One domain is the Corsica Basin in the west that formed before the main rift phase of the northern Tyrrhenian Sea opening (\~{}8-4 Ma). The second domain is rifted continental crust characterized by tilted blocks and half-graben structures in the central region and at the Latium Margin. These two domains are separated by a deep (\~{}10 km) sedimentary complex of the eastern portion of the Corsica Basin. Travel-time tomography of wide-angle seismic data reveals the crustal architecture and a subhorizontal 15-17 {\textpm} 1 km deep Moho discontinuity under the basin. To estimate the amount of horizontal extension we have identified the pre-, syn-, and post-tectonic sedimentary units and calculated the relative displacement of faults. We found that major faults initiated at angles of 45{\textdegree}-50{\textdegree} and that the rifted domain is horizontally stretched by a factor of $\beta$ \~{} 1.3 (\~{}8-10 mm/a). The crust has been thinned from \~{}24 to \~{}17 km indicating a similar amount of extension (\~{}30\%). The transect represents one of the best imaged early rifts and implies that the formation of crustal-scale detachments, or long-lived low-angle normal faults, is not a general feature that controls the rift initiation of continental crust. Other young rift basins, like the Gulf of Corinth, the Suez Rift or Lake Baikal, display features resembling the northern Tyrrhenian Basin, suggesting that half-graben formations and distributed homogeneous crustal thinning are a common feature during rift initiation. {\textcopyright}2013. American Geophysical Union. All Rights Reserved.},
	keywords = {Basin formation, Continental extension, Multichannel seismic data, Rifting, Tyrrhenian Sea, Wide-Angle data},
	issn = {15252027},
	doi = {10.1002/ggge.20180},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84885100133\&partnerID=tZOtx3y1},
	author = {Moeller, S. and Grevemeyer, I. and Ranero, C. R. and Berndt, C. and Klaeschen, D. and Sallar{\`e}s, V. and Zitellini, N. and de Franco, R.}
}
@article {Mel{\'e}ndez2013243,
	title = {{Origin of water layer multiple phases with anomalously high amplitude in near-seafloor wide-angle seismic recordings}},
	journal = {Geophysical Journal International},
	volume = {196},
	number = {1},
	year = {2013},
	pages = {243{\textendash}252},
	abstract = {Water layer multiple seismic phases are recorded at ocean bottom seismometers and hydrophones as arrivals that correspond to the reflection of the primary phases at the sea-free air interface. In regions of low to moderate seabed relief, the shape of these phases mimics that of the primary phases with a traveltime delay that depends on the water layer thickness at the receiver location. Given their longer travel paths, multiple phases should have smaller amplitudes than their corresponding primary phases. However, depending on the geological context it can be relatively common to observe the opposite, which results in the identification of the multiple phases at longer offsets than the primary events. In this paper, we examine the origin of this apparently paradoxical phenomenon by analysing the combined effect of the major factors potentially involved: the source frequency content, the subsurface velocity distribution, the receiver-seafloor distance, the geometrical spreading and attenuation of sound waves and the ambient noise level.We use synthetic modelling to show that for certain combinations of these factors, the interference between the multiple and its reflection at the seafloor is constructive and has a higher amplitude than the primary wave. Our analysis indicates that in the most favourable cases the phases resulting from this interference can be observed at offsets some tens of kilometres longer than their corresponding primary phases, and thus they can provide useful information for velocity modelling. {\textcopyright} The Authors 2013. Published by Oxford University Press on behalf of The Royal Astronomical Society.},
	keywords = {ambient noise, Controlled source seismology, Controlled-source seismologies, Earthquake effects, Geometrical spread, hydrophone, Numerical approximations and analysis, numerical method, ocea, Seismology, Site effects, Wave propagation},
	issn = {0956540X},
	doi = {10.1093/gji/ggt391},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84890885715\&partnerID=tZOtx3y1 http://www.scopus.com/inward/record.url?eid=2-s2.0-84890885715\&partnerID=40\&md5=a3729b5c20fafb9373a2a82c94b34990},
	author = {Mel{\'e}ndez, A.a and Sallar{\`e}s, V.a and Ranero, C.R.b R. and Kormann, J.c and Mel{\'e}ndez, A. and Sallar{\`e}s, V.}
}
@article {Gutscher2012,
	title = {{The Gibraltar subduction: A decade of new geophysical data}},
	journal = {Tectonophysics},
	volume = {574-575},
	year = {2012},
	month = {oct},
	pages = {72{\textendash}91},
	abstract = {The Gibraltar arc, spans a complex portion of the Africa-Eurasia plate boundary marked by slow oblique convergence and intermediate and deep focus seismicity. The seemingly contradictory observations of a young extensional marine basin surrounded by an arcuate fold-and-thrust belt, have led to competing geodynamic models (delamination and subduction). Geophysical data acquired in the past decade provide a test for these models and support a narrow east-dipping, subduction zone. Seismic refraction studies indicate oceanic crust below the western Gulf of Cadiz. Tomography of the upper mantle reveals a steep, east-dipping high P-wave velocity body, beneath Gibraltar. The anisotropic mantle fabric from SKS splitting shows arc-parallel "fast directions", consistent with toroidal flow around a narrow, westward retreating subducting slab. The accompanying WSW advance of the Rif-Betic mountain belt has constructed a thick pile of deformed sediments, an accretionary wedge, characterized by west-vergent thrust anticlines. Bathymetric swath-mapping images an asymmetric embayment at the deformation front where a 2. km high basement ridge has collided. Subduction has slowed significantly since 5. Ma, but deformation of recent sediments and abundant mud volcanoes suggest ongoing activity in the accretionary wedge. Three possible origins for this deformation are discussed; gravitational spreading, overall NW-SE convergence between Africa and Iberia and finally a WSW tectonic push from slow, but ongoing roll-back subduction. In the absence of arc volcanism and shallow dipping thrust type earthquakes, evidence in favor of present-day subduction can only be indirect and remains the object of debate. Continued activity of the subduction offers a possible explanation for great (M. >. 8.5) earthquakes known to affect the area, like the famous 1755 Great Lisbon earthquake. Recent GPS studies show SW motion of stations in N Morocco at velocities of 3-6. mm/yr indicating the presence of an independent block, a "Rif-Betic-Alboran" microplate, situated between Iberia and Africa. {\textcopyright} 2012 Elsevier B.V.},
	keywords = {Accretionary wedge, Active deformation, earthquakes, Iberia, Roll-back subduction, Tethys oceanic lithosphere},
	issn = {00401951},
	doi = {10.1016/j.tecto.2012.08.038},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84867273669\&partnerID=tZOtx3y1},
	author = {Gutscher, M.-A. and Dominguez, S. and Westbrook, G.K. and Le Roy, P. and Rosas, F. and Duarte, J.C. and Terrinha, P. and Miranda, J.M. and Graindorge, D. and Gailler, A. and Sallar{\`e}s, V. and Bartolome, R.}
}
@conference {Ranero2012,
	title = {{The tectonic structure of the Tyrrhenian Basin, a complex interaction among faulting and magmatism}},
	booktitle = {Rendiconti Online Societa Geologica Italiana},
	volume = {21},
	number = {PART 1},
	year = {2012},
	pages = {251{\textendash}252},
	keywords = {Crustal structure, Tectonic structure, Tyrrhenian rifting},
	issn = {20358008},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84872362909\&partnerID=tZOtx3y1},
	author = {Ranero, C. R. and Sallar{\`e}s, V. and Zitellini, N. and Grevemeyer, I. and Guzman, M. and Prada, M. and Moeller, S. and de Franco, R.}
}
@article {Kormann2011,
	title = {{Application of acoustic full waveform inversion to retrieve high-resolution temperature and salinity profiles from synthetic seismic data}},
	journal = {Journal of Geophysical Research},
	volume = {116},
	number = {C11},
	year = {2011},
	month = {nov},
	pages = {C11039},
	abstract = {Recent works show that multichannel seismic (MCS) systems are able to provide detailed information on the oceans{\textquoteright} fine structure. The aim of this paper is to analyze whether 1-D full waveform inversion algorithms are suitable to recover the extremely weak acoustic impedance contrasts associated to the oceans{\textquoteright} fine structure, as well as their potential to image meso-scale objects such as meddies. We limited our analysis to synthetic, noise-free data, in order to identify some methodological issues related to this approach under idealistic conditions (e.g., 1-D wave propagation, noise-free data, known source wavelet). We first discuss the influence of the starting model in the context of the multi-scale strategy that we have implemented. Then we show that it is possible to retrieve not only sound speed but also salinity and temperature contrasts within reasonable bounds from the seismic data using Neural Network relationships trained with regional oceanographic data sets. Potentially, the vertical resolution of the obtained models, which depends on the maximum frequency inverted, is of the order of 5-10 m, whereas the root mean square error of the inverted properties is shown to be \~{}0.5 m/s for sound speed, 0.1C for temperature, and 0.06 for salinity. To conclude this study, we have inverted synthetic data simulated along an oceanographic transect acquired during the EU-funded Geophysical Oceanography (GO) project. The results demonstrate the applicability of the method for synthetic data, as well as its potential to define oceanographic features along 2-D transects at full ocean depth with excellent lateral resolution. Copyright 2011 by the American Geophysical Union.},
	issn = {0148-0227},
	doi = {10.1029/2011JC007216},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-82355181440\&partnerID=tZOtx3y1},
	author = {Kormann, J. and Biescas, B. and Korta, N. and De La Puente, J. and Sallar{\`e}s, V.}
}
@conference {Melendez2010,
	title = {{Appraisal of joint refraction and reflection travel-time tomography in the context of weathering correction}},
	booktitle = {72nd European Association of Geoscientists and Engineers Conference and Exhibition 2010: A New Spring for Geoscience. Incorporating SPE EUROPEC 2010},
	volume = {6},
	year = {2010},
	pages = {4692{\textendash}4696},
	abstract = {We propose an application of joint refraction and reflection travel-time tomography to determine both velocity and thickness of the weathering layer to be used in statics correction. This low velocity layer affects the quality of seismic images. The innovative aspect of our approach is the use of refracted and reflected phases. This remarkably reduces the trade-off between depth and velocity. First arrivals can be automatically picked and the reflection at the layer bottom can be easily identified because of the high impedance contrast with the basement. Synthetic data are generated for a reference model with an acquisition geometry simulating production experiments. The reference model is modified by adding a velocity perturbation and displacing the reflector to create the initial model for the inversion. Travel-time residuals decrease from \~{}1 s to \~{}0.1 s and the reflector is recovered to within {\textpm}2 m. A Monte Carlo analysis is performed to calculate the mean deviation and its reduction as a measure of the model parameters uncertainty. The improvement (10-50\%) is more significant in areas covered by reflections and refractions, while the reflector is again limited to a \~{}2 m range. We are testing this application with real data. {\textcopyright} 2010, European Association of Geoscientists and Engineers.},
	isbn = {9781617386671},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-78249271372\&partnerID=tZOtx3y1},
	author = {Mel{\'e}ndez, A. and De La Puente, J. and Sallar{\`e}s, V. and Ranero, C. R.}
}
@article {Geissler2010,
	title = {{Focal mechanisms for sub-crustal earthquakes in the Gulf of Cadiz from a dense OBS deployment}},
	journal = {Geophysical Research Letters},
	volume = {37},
	number = {18},
	year = {2010},
	month = {sep},
	pages = {n/a{\textendash}n/a},
	abstract = {An eleven-month deployment of 25 ocean bottom seismometers provides an unprecedented opportunity to study low-magnitude local earthquakes in the complex transpressive plate boundary setting of the Gulf of Cadiz, known for the 1755 Lisbon earthquake and tsunami. 36 relocated earthquakes (ML 2.2 to 4.8) concentrate at 40-60 km depth, near the base of the seismogenic layer in \~{}140 Ma old oceanic mantle lithosphere, and roughly align along two perpendicular, NNE-SSW and WNW-ESE striking structures. First motion focal mechanisms indicate compressive stress for the cluster close to the northern Horseshoe fault termination which trends perpendicular to plate convergence. Focal mechanisms for the second cluster near the southern termination of the Horseshoe fault indicate a strike-slip regime, providing evidence for present-day activity of a dextral shear zone proposed to represent the Eurasia-Africa plate contact. We hypothesize that regional tectonics is characterized by slip partitioning. {\textcopyright} 2010 by the American Geophysical Union.},
	issn = {00948276},
	doi = {10.1029/2010GL044289},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-77957722745\&partnerID=tZOtx3y1},
	author = {Geissler, W. H. and Matias, L. and Stich, D. and Carrilho, F. and Jokat, W. and Monna, S. and IbenBrahim, A. and Mancilla, F. and Gutscher, M.-A. and Sallar{\`e}s, V. and Zitellini, N.}
}
@conference {DeLaPuente2010,
	title = {{The potential of discontinuous Galerkin methods for full waveform tomography}},
	booktitle = {72nd European Association of Geoscientists and Engineers Conference and Exhibition 2010: A New Spring for Geoscience. Incorporating SPE EUROPEC 2010},
	volume = {6},
	year = {2010},
	pages = {4144{\textendash}4148},
	abstract = {We present a discontinuous Galerkin solver for Full Waveform Tomography applications in seismic exploration. We discuss the advantages and drawbacks of using unstructured meshes in the model discretization and present a numerical example. {\textcopyright} 2010, European Association of Geoscientists and Engineers.},
	isbn = {9781617386671},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-78249285605\&partnerID=tZOtx3y1},
	author = {De La Puente, J. and Sallar{\`e}s, V. and Ranero, C. R.}
}
@article {Buffett2010,
	title = {{Stochastic heterogeneity mapping around a mediterranean salt lens}},
	journal = {Ocean Science},
	volume = {6},
	number = {1},
	year = {2010},
	pages = {423{\textendash}429},
	abstract = {We present the first application of Stochastic Heterogeneity Mapping based on the band-limited von K{\'a}rm{\'a}n function to a seismic reflection stack of a Mediterranean water eddy (meddy), a large salt lens of Mediterranean water. This process extracts two stochastic parameters directly from the reflectivity field of the seismic data: the Hurst number, which ranges from 0 to 1, and the correlation length (scale length). Lower Hurst numbers represent a richer range of high wavenumbers and correspond to a broader range of heterogeneity in reflection events. The Hurst number estimate for the top of the meddy (0.39) compares well with recent theoretical work, which required values between 0.25 and 0.5 to model internal wave surfaces in open ocean conditions based on simulating a Garrett-Munk spectrum (GM76) slope of \&-2. The scale lengths obtained do not fit as well to seismic reflection events as those used in other studies to model internal waves. We suggest two explanations for this discrepancy: (1) due to the fact that the stochastic parameters are derived from the reflectivity field rather than the impedance field the estimated scale lengths may be underestimated, as has been reported; and (2) because the meddy seismic image is a two-dimensional slice of a complex and dynamic three-dimensional object, the derived scale lengths are biased to the direction of flow. Nonetheless, varying stochastic parameters, which correspond to different spectral slopes in the Garrett-Munk spectrum (horizontal wavenumber spectrum), can provide an estimate of different internal wave scales from seismic data alone. We hence introduce Stochastic Heterogeneity Mapping as a novel tool in physical oceanography.},
	issn = {18120784},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-77950468840\&partnerID=tZOtx3y1},
	author = {Buffett, G. G. and Hurich, C. A. and Vsemirnova, E. A. and Hobbs, R. W. and Sallar{\`e}s, V. and Carbonell, R. and Klaeschen, D. and Biescas, B.}
}
@article {Hobbs2009,
	title = {{Effect of seismic source bandwidth on reflection sections to image water structure}},
	journal = {Geophysical Research Letters},
	volume = {36},
	number = {21},
	year = {2009},
	month = {nov},
	pages = {L00D08},
	abstract = {The seismic reflection profile is the convolution of the seismic acquisition impulse response and the target impedance contrasts. In the ocean, these contrasts are mainly determined by the widths and gradients of the temperature transitions between the different water masses. Hence seismic oceanography profiles are sensitive to the frequency bandwidth of the seismic acquisition system. We tested a novel seismic source that allowed us to simultaneously profile the ocean with differing impulse responses. We show that frequencies \~{}20 Hz are best to delineate large impedance contrasts that occur over a vertical scale of several tens of meters whereas frequencies \~{}80 Hz image the boundaries of layers of around 10 m. We demonstrate a towed acquisition system that can operate from a research vessel to give a bandwidth from 10 to 120 Hz that could, if required, be modified to provide frequencies up to 200 Hz. Copyright 2009 by the American Geophysical Union.},
	issn = {0094-8276},
	doi = {10.1029/2009GL040215},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-72049094260\&partnerID=tZOtx3y1},
	author = {Hobbs, R. W. and Klaeschen, D. and Sallar{\`e}s, V. and Vsemirnova, E. and Papenberg, C.}
}
@article {Sallares2009,
	title = {{Relative contribution of temperature and salinity to ocean acoustic reflectivity}},
	journal = {Geophysical Research Letters},
	volume = {36},
	number = {20},
	year = {2009},
	month = {oct},
	pages = {L00D06},
	abstract = {Marine seismic data display laterally coherent reflectivity from the water column that is attributed to fine-scale oceanic layering. The amplitude of the different reflections is the expression of acoustic impedance contrasts. between neighbouring water masses, and therefore water reflectivity maps the ocean{\textquoteright}s vertical sound speed and density (i.e., temperature and salinity) variations. Here we determine the relative contribution of each parameter by computing the temperature and salinity partial derivatives of sound speed and density, and using them to estimate reflection coefficients from a real oceanographic dataset. The results show that the mean contribution of density variations is 5-10\%, while 90-95\% is due to sound speed variations. On average, 80\% of reflectivity comes from temperature contrasts. Salinity contribution averages 20\%, but it is highly variable and reaches up to 40\% in regions prone to diffusive convection such as the top of the Mediterranean Undercurrent in the Gulf of Cadiz. Copyright 2009 by the American Geophysical Union.},
	issn = {0094-8276},
	doi = {10.1029/2009GL040187},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-72149084920\&partnerID=tZOtx3y1},
	author = {Sallar{\`e}s, V. and Biescas, B. and Buffett, G. and Carbonell, R. and Danobeitia, J. J. and Pelegr{\'\i}, J. L.}
}
@article {Buffett2009,
	title = {{Seismic reflection along the path of the Mediterranean Undercurrent}},
	journal = {Continental Shelf Research},
	volume = {29},
	number = {15},
	year = {2009},
	month = {aug},
	pages = {1848{\textendash}1860},
	abstract = {Seismic reflection profiling is applied to the study of large scale physical oceanographic processes in the Gulf of C{\'a}diz and western Iberian coast, coinciding with the path of the Mediterranean Undercurrent. The multi-channel seismic reflection method provides clear images of thermohaline fine structure with a horizontal resolution approximately two orders of magnitude higher than CTD casting. The seismic data are compared with co-located historical oceanographic data. Three seismic reflectivity zones are identified: North Atlantic Central Water, Mediterranean Water and North Atlantic Deep Water. Seismic evidence for the path of the Mediterranean Undercurrent is found in the near-slope reflectivity patterns, with rising reflectors between about 500 and 1500 m. However, the core of the undercurrent is largely transparent. Seismic images show that central and, particularly, intermediate Mediterranean Waters have fine structure coherent over horizontal distances of several tens of kilometers. However, the intensity of the reflectors, and their horizontal coherence, decreases downstream. This change in seismic reflectivity is probably the result of diminished vertical thermohaline contrasts between adjacent water masses, so that double-diffusion processes become unable to sustain temperature and salinity staircases. Comparison of root-mean-square seismic amplitudes with temperature and salinity differences between the Mediterranean Undercurrent and the overlying central waters suggests a causal relationship between observed thermohaline fine structure and true seismic amplitudes. We estimate that, within this intermediate water stratum, impedance contrasts are mainly controlled by sound speed contrasts (a factor between 3.5 and 10 times larger than density contrasts), which are mainly controlled by temperature contrasts (a factor between 1.5 and 5 times larger than salinity contrasts). {\textcopyright} 2009 Elsevier Ltd. All rights reserved.},
	keywords = {Amplitude, Entrainment, Mediterranean Undercurrent, Mixing, Salinity, Seismic oceanography, Temperature, thermohaline fine structure},
	issn = {02784343},
	doi = {10.1016/j.csr.2009.05.017},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-69249209739\&partnerID=tZOtx3y1},
	author = {Buffett, G.G. and Biescas, B. and Pelegr{\'\i}, J.L. and Mach{\'\i}n, F. and Sallar{\`e}s, V. and Carbonell, R. and Klaeschen, D. and Hobbs, R.}
}
@conference {Shariat-Panahi2008,
	title = {{Design, Characterization and Calibration of a Short-Period Ocean Bottom Seismometer (OBS)}},
	booktitle = {2008 IEEE Instrumentation and Measurement Technology Conference},
	year = {2008},
	month = {may},
	pages = {495{\textendash}500},
	publisher = {IEEE},
	organization = {IEEE},
	abstract = {First part of this paper presents an Ocean Bottom Seismometers (OBS) designed and constructed for mid-term deployments in order to study the earth dynamics and internal structure. Many marine research institutes have developed such equipment, however there is no standard method for their characterization and calibration. The second part discusses the characterization tests based on the international standards carried out to present the specifications of the equipment built. Calibration of the constructed OBS is carried out through an oceanographic cruise using a widely used reference OBS. Data quality of the instruments is evaluated by direct inspection of the corresponding seismic record sections. {\textcopyright}2008 IEEE.},
	keywords = {Analog-to-digital converter, Calibration, Datalogger, Dynamic range, Effective number of bits, Geophone, Jitter, Ocean bottom seismometer (OBS), Seismic record section, Time base},
	isbn = {978-1-4244-1540-3},
	issn = {10915281},
	doi = {10.1109/IMTC.2008.4547086},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-51349130474\&partnerID=tZOtx3y1},
	author = {Shariat-Panahi, S. and M{\`a}nuel, A. and Alegria, F. and Roset, X. and Bermudez, A. and Sallar{\`e}s, V.}
}
@article {Biescas2008,
	title = {{Imaging meddy finestructure using multichannel seismic reflection data}},
	journal = {Geophysical Research Letters},
	volume = {35},
	number = {11},
	year = {2008},
	month = {jun},
	pages = {L11609},
	abstract = {This work illustrates the great potential of multichannel seismic reflection data to extract information from the finestructure of meddies with exceptional lateral resolution (10-15 m). We present seismic images of three meddies acquired in the Gulf of Cadiz (SW Iberian Peninsula), which consist of concentric reflectors forming oval shapes that sharply contrast with the background oceanic structure. The seismic images reveal the presence of different regions within the meddies that are consistent with those observed in historical temperature (T) and salinity (S) data. The core region, characterized by smooth T and S variations, is weakly reflective. The double-diffusive upper and lower boundaries and the lateral-interleaving outer edges, characterized by stronger T and S contrasts, display strong reflectivity bands. These new observations clearly show differences between layers developed at the upper and lower boundaries that can contribute to th knowledge of mixing processes and layering formation in oceans. Copyright 2008 by the American Geophysical Union.},
	issn = {0094-8276},
	doi = {10.1029/2008GL033971},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-49849096389\&partnerID=tZOtx3y1},
	author = {Biescas, B. and Sallar{\`e}s, V. and Pelegr{\'\i}, J. L. and Mach{\'\i}n, F. and Carbonell, R. and Buffett, G. and Danobeitia, J. J. and Calahorrano, A.}
}
@article {Panahi2008,
	title = {{A Low-Power Datalogger Based on CompactFlash Memory for Ocean Bottom Seismometers}},
	journal = {IEEE Transactions on Instrumentation and Measurement},
	volume = {57},
	number = {10},
	year = {2008},
	month = {oct},
	pages = {2297{\textendash}2303},
	abstract = {In the last decade, marine scientific instruments have been in high demand, particularly autonomous instruments that are capable of staying under water for a long time while performing continuous data acquisition and storage. This paper introduces an instrument under development that is used for the study of ocean bottom sublayers and microseismic detection. The power consumption of the equipment has been minimized to increase autonomy, and CompactFlash memory cards have been used as the storage element. Development of such equipment is a joint effort between different disciplines, such as electronics, mechanics, geophysics, underwater communications, etc. The acquisition system was tested both in the laboratory and under real environmental conditions in the summer of 2005, and the results have been evaluated. {\textcopyright} 2008 IEEE.},
	keywords = {Analog-to-digital (A/D) converter, CompactFlash memory, Datalogger, Effective number of bits (ENOB), Ocean bottom seismometer (OBS), Power consumption, Time base},
	issn = {0018-9456},
	doi = {10.1109/TIM.2008.919005},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-52649175960\&partnerID=tZOtx3y1},
	author = {Panahi, S.S. and Ventosa, S. and Cadena, J. and Manuel-Lazaro, A. and Bermudez, A. and Sallar{\`e}s, V. and Piera, J.}
}
@article {Rodriguez2008,
	title = {{A new multi-platform modular software tool for wide-angle reflection/refraction seismic data processing and representation (WASPAR)}},
	journal = {Computers \& Geosciences},
	volume = {34},
	number = {5},
	year = {2008},
	pages = {456{\textendash}463},
	abstract = {WASPAR (Wide-Angle reflection-refraction Seismic data Processing And Representation) is a new free multi-platform software tool to process and display wide-angle seismic data. It has been designed to read different raw data formats, construct record sections, process them using existing and newly developed algorithms, pick seismic phases and generate graphic files using a single, user-friendly interface. The main characteristics of WASPAR are its flexibility and expandability. It has been designed in a modular way using a plug-in architecture to manage raw data access and processing functionalities. We thus obtain a stable base easily maintainable and expandable. We have chosen the C ++ programming language in combination with an object oriented methodology to facilitate the development of a multi-platform software tool, which is already available on Linux and MS Windows. In order to allow its expansion and upgrade, the program will be freely distributed under the terms of GPL license. The philosophy of this software tool is to leave it open to external contributions. {\textcopyright} 2007 Elsevier Ltd. All rights reserved.},
	keywords = {Object oriented programming, Plug-in, Signal processing, Software, wide-angle seismics},
	issn = {00983004},
	doi = {10.1016/j.cageo.2007.04.011},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-39149086998\&partnerID=tZOtx3y1},
	author = {Rodr{\'\i}guez, I. and Simon, C. and Sallar{\`e}s, V. and Carlosena, A. and M{\`a}nuel, A. and Da{\~n}obeitia, J.J.}
}
@conference {Shariat-Panahi2008a,
	title = {{Ocean Bottom Seismometer (OBS): An instrument for marine seismic data acquisition}},
	booktitle = {2008 IEEE International Symposium on Industrial Electronics},
	year = {2008},
	month = {jun},
	pages = {1183{\textendash}1186},
	publisher = {IEEE},
	organization = {IEEE},
	abstract = {The OBS (Ocean Bottom Seismoemter) has been a key instrument for geophysical study of sea sub-bottom layers in the last decades. Now scientists are demanding highly relaible autonomous equipment capable of staying underwater for long periods of time and therefore handling large data storage. Power consumption of the acquisition system as well as a stable time base with temperature are the main issues in order to achieve high autonomy together with a good data quality. This paper presents a new Ocean Bottom Seismometer designed to be used in marine mid-term surveys. To achieve our goals, a new low power datalogger with high resolution and Signal-to-Noise Ratio (SNR) based on Compactflash memory card is designed to enable continous data acquisition. The equipment has been evaluated in real environmental conditions during a test cruise in 2006. {\textcopyright} 2008 IEEE.},
	keywords = {Acquisition system, Analog to digital converter, Geophone, Ocean bottom seismometer (OBS)},
	isbn = {978-1-4244-1665-3},
	doi = {10.1109/ISIE.2008.4677225},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-57849111983\&partnerID=tZOtx3y1},
	author = {Shariat-Panahi, S. and M{\`a}nuel, A. and Bermudez, A. and Ambros, M. and Sallar{\`e}s, V. and Molino, E.}
}
