Context. The stable propagation of jets in FRII sources is remarkable if one takes into account that large-scale jets are subjected to potentially highly disruptive three-dimensional (3D) Kelvin-Helmholtz instabilities. Aims. Numerical simulations can address this problem and help clarify the causes of this remarkable stability. Following previous studies of the stability of relativistic flows in two dimensions (2D), it is our aim to test and extend the conclusions of such works to three dimensions. Methods. We present numerical simulations for the study of the stability properties of 3D, sheared, relativistic flows. This work uses a fully parallelized code (Ratpenat) that solves equations of relativistic hydrodynamics in 3D.Results. The results of the present simulations confirm those in 2D. We conclude that the growth of resonant modes in sheared relativistic flows could be important in explaining the long-term collimation of extragalactic jets.

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Bouguer anomaly maps are powerful cartographic tools used mainly by geoscientists and natural resources' companies (oil, mining, etc.) since they reflect rock density distribution at different depths, allowing the identification of different tectonic features. At upper crustal levels, Bouguer anomaly maps can help, for instance, in characterizing possible ore deposits, ground water reservoirs, petroleum resources, CO 2 storage sites and sedimentary basins; at deeper crustal levels they can help to further refine seismic velocity models or other integrated geophysical models and thus help in deciphering the lateral density variations within the crust and the geometry of the base of the crust. This new Bouguer anomaly map at a 1:1,500,000 scale is based on the compilation of 210,283 gravity stations covering the Iberian Peninsula (c. 583,254 km 2 ). The new map upgrades previous maps in two ways: (1) it is built up from a database with a 15% more spatial coverage than previous compilations and (2) it is freely available. This map show shorter wavelengths than previous published maps thus allowing investigation of smaller geological features. ARTICLE HISTORY

a b s t r a c t a r t i c l e i n f oIn the Campo de Calatrava Volcanic Field (CCVF, Central Spain), the eruption of Pliocene-Pleistocene maar craters into two clearly distinct types of pre-volcanic rocks allows the observation and comparison of hardsubstrate and soft-substrate maar lakes. Hard-substrate maars formed when phreatomagmatic processes affected the jointed, Paleozoic igneous and metamorphic rocks (hard substrate), giving rise to funnel-like maar lake basins. Soft-substrate maars resulted from phreatomagmatic volcanic processes affecting poorlyconsolidated Pliocene sediments, forming bowl-like maar lake basins. Pre-volcanic bedrock determined the post-eruptive lacustrine architecture in the craters and favored a higher preservation of hard-substrate maars in comparison to soft-substrate maars. This is because the hard-substrate maars, surrounded by a deep stable crater wall, are more capable of collecting sediments in their basins. These sediments could be preserved for longer than similar deposits in broad, shallow maars with a soft substrate. Ancient soft-substrate maars do not usually preserve their original morphology well and can be identified only by their lacustrine deposits. Carbonate lacustrine/palustrine deposits surrounding a bowl-like depression are the remnants of this second type of maar lake, and allow reconstruction of the original morphology of ancient soft-substrate maar craters. Geophysical (electrical tomography ground surveys) and geomorphologic-geologic mapping techniques were combined with fieldwork and facies analysis in order to locate and accurately characterize the PliocenePleistocene soft-substrate maar volcanic structures of the CCVF.