@article {Mel{\'e}ndez2015158,
	title = {{TOMO3D: 3-D joint refraction and reflection traveltime tomography parallel code for active-source seismic data-synthetic test}},
	journal = {Geophysical Journal International},
	volume = {203},
	number = {1},
	year = {2015},
	pages = {158{\textendash}174},
	abstract = {We present a new 3-D traveltime tomography code (TOMO3D) for the modelling of active-source seismic data that uses the arrival times of both refracted and reflected seismic phases to derive the velocity distribution and the geometry of reflecting boundaries in the subsurface. This code is based on its popular 2-D version TOMO2D from which it inherited the methods to solve the forward and inverse problems. The traveltime calculations are done using a hybrid ray-tracing technique combining the graph and bending methods. The LSQR algorithm is used to perform the iterative regularized inversion to improve the initial velocity and depth models. In order to cope with an increased computational demand due to the incorporation of the third dimension, the forward problem solver, which takes most of the run time (\~{}90 per cent in the test presented here), has been parallelized with a combination of multi-processing and message passing interface standards. This parallelization distributes the ray-tracing and traveltime calculations among available computational resources. The code{\textquoteright}s performance is illustrated with a realistic synthetic example, including a checkerboard anomaly and two reflectors, which simulates the geometry of a subduction zone. The code is designed to invert for a single reflector at a time. A data-driven layer-stripping strategy is proposed for cases involving multiple reflectors, and it is tested for the successive inversion of the two reflectors. Layers are bound by consecutive reflectors, and an initial velocity model for each inversion step incorporates the results from previous steps. This strategy poses simpler inversion problems at each step, allowing the recovery of strong velocity discontinuities that would otherwise be smoothened. {\textcopyright} The Authors 2015. Published by Oxford University Press on behalf of The Royal Astronomical Society.},
	doi = {10.1093/gji/ggv292},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84942105766\&partnerID=40\&md5=95ac8480fd67102b8f5322381f9ff8ef},
	author = {Mel{\'e}ndez, A.a and Korenaga, J.b and Sallar{\`e}s, V.a and Miniussi, A.c and Ranero, C.R.d}
}
@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.}
}
