@article {Jim{\'e}nezTejero2015632, title = {{Comparative study of objective functions to overcome noise and bandwidth limitations in full waveform inversion}}, journal = {Geophysical Journal International}, volume = {203}, number = {1}, year = {2015}, pages = {632{\textendash}645}, abstract = {Ongoing works on full waveform inversion (FWI) are yielding an increasing number of objective functions as alternative to the traditional L2-waveform. These studies aim at designing more robust functions and inversion strategies to reduce the intrinsic dependence of the FWI results on (1) the initial model and (2) the lowest frequency present in field data. In this work, we perform a comparative study of five objective functions in time domain under a common 2-D-acoustic FWI scheme using the Marmousi model as benchmark. In particular, we compare results obtained with L2-based functions that consider the minimization of different wave attributes; the waveform-based, non-integration-method; instantaneous envelope; a modified version of the wrapped instantaneous phase and an improved version of the cross-correlation travel time (CCTT) method; and hybrid strategies combining some of them. We evaluate the robustness of these functionals as a function of their performance with and without low frequencies in the data and the presence of random white Gaussian noise. Our results reveal promising strategies to invert noisy data with limited low-frequency content (>=4 Hz), which is the single strategy using the instantaneous phase objective function followed by the hybrid strategies using the instantaneous phase or CCTT as initial models, in particular the combinations [I. Phase + Waveform], [CCTT + Waveform] and [CCTT + I. Phase]. {\textcopyright} The Authors 2015. Published by Oxford University Press on behalf of The Royal Astronomical Society.}, doi = {10.1093/gji/ggv288}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84942124341\&partnerID=40\&md5=a3d1892b9dda25cdcea5fea23bef2d14}, author = {Jim{\'e}nez Tejero, C.E.a and Dagnino, D.a and Sallar{\`e}s, V.a and Ranero, C.R.b} } @article {Prada201563, title = {{The complex 3-D transition from continental crust to backarc magmatism and exhumed mantle in the Central Tyrrhenian basin}}, journal = {Geophysical Journal International}, volume = {203}, number = {1}, year = {2015}, pages = {63{\textendash}78}, abstract = {Geophysical data from the MEDOC experiment across the Northern Tyrrhenian backarc basin has mapped a failed rift during backarc extension of cratonic Variscan lithosphere. In contrast, data across the Central Tyrrhenian have revealed the presence of magmatic accretion followed by mantle exhumation after continental breakup. Here we analyse the MEDOC transect E-F, which extends from Sardinia to the Campania margin at 40.5{\textdegree}N, to define the distribution of geological domains in the transition from the complex Central Tyrrhenian to the extended continental crust of the Northern Tyrrhenian. The crust and uppermost mantle structure along this \~{}400-km-long transect have been investigated based on wide-angle seismic data, gravity modelling and multichannel seismic reflection imaging. The P-wave tomographic model together with a P-wave-velocity-derived density model and the multichannel seismic images reveal seven different domains along this transect, in contrast to the simpler structure to the south and north. The stretched continental crust under Sardinia margin abuts the magmatic crust of Cornaglia Terrace, where accretion likely occurred during backarc extension. Eastwards, around Secchi seamount, a second segment of thinned continental crust (7-8 km) is observed. Two short segments of magmatically modified continental crust are separated by the \~{}5-km-wide segment of the Vavilov basin possibly made of exhumed mantle rocks. The eastern segment of the 40.5{\textdegree}N transect E-F is characterized by continental crust extending from mainland Italy towards the Campania margin. Ground truthing and prior geophysical information obtained north and south of transect E-F was integrated in this study to map the spatial distribution of basement domains in the Central Tyrrhenian basin. The northward transition of crustal domains depicts a complex 3-D structure represented by abrupt spatial changes of magmatic and non-magmatic crustal domains. These observations imply rapid variations of magmatic activity difficult to reconcile with current models of extension of continental lithosphere essentially 2-D over long distances. {\textcopyright} The Authors 2015. Published by Oxford University Press on behalf of The Royal Astronomical Society.}, doi = {10.1093/gji/ggv271}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84942122080\&partnerID=40\&md5=02bdb76af30a3b605991623f90757147}, author = {Prada, M.a and Sallar{\`e}s, V.a and Ranero, C.R.b and Vendrell, M.G.a and Grevemeyer, I.c and Zitellini, N.d and de Franco, R.e} } @article {Geersen2015, title = {{Subducting seamounts control interplate coupling and seismic rupture in the 2014 Iquique earthquake area}}, journal = {Nature Communications}, volume = {6}, year = {2015}, abstract = {To date, the parameters that determine the rupture area of great subduction zone earthquakes remain contentious. On 1 April 2014, the Mw 8.1 Iquique earthquake ruptured a portion of the well-recognized northern Chile seismic gap but left large highly coupled areas un-ruptured. Marine seismic reflection and swath bathymetric data indicate that structural variations in the subducting Nazca Plate control regional-scale plate-coupling variations, and the limited extent of the 2014 earthquake. Several under-thrusting seamounts correlate to the southward and up-dip arrest of seismic rupture during the 2014 Iquique earthquake, thus supporting a causal link. By fracturing of the overriding plate, the subducting seamounts are likely further responsible for reduced plate-coupling in the shallow subduction zone and in a lowly coupled region around 20.5{\textdegree}S. Our data support that structural variations in the lower plate influence coupling and seismic rupture offshore Northern Chile, whereas the structure of the upper plate plays a minor role. {\textcopyright} 2015 Macmillan Publishers Limited. All rights reserved.}, doi = {10.1038/ncomms9267}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84942875520\&partnerID=40\&md5=c48e69118579945090a1454f6db7407e}, author = {Geersen, J.a and Ranero, C.R.b and Barckhausen, U.c and Reichert, C.c} }