[en] In this study we analyse three wide-angle seismic profiles in the Pyrenees to provide new insights into their crustal structure. Several earthquakes with magnitudes greater than 2.5 that occurred in the vicinity of the analysed profiles have been used as the seismic source. We demonstrate the feasibility of using natural seismicity as the seismic source, which would allow using deployments of seismic stations designed for other objectives. We have analysed a total of three profiles in this study, two of them being located in the eastern Pyrenees (Cataluña) with N-S and E-O directions, and the third in the western Pyrenees (Navarra) with NE-SO orientation. All of them were originally deployed to record teleseisms for receiver function analysis. Profiles in the eastern Pyrenean edge constrain the top of the lower crust at a depth of 20 km. In the easternmost sector of the E-W profile, Moho has been imaged as an eastward rising ramp, with a depth decreasing from 35- 40 km in the middle of the profile to a depth of 25 km in the eastern edge. The Navarra profile allowed us to constrain the crustal structure of the western Pyrenean edge in detail. The obtained model allowed the imaging of the mid-lower crustal indentation between the Iberian and European plates. The European Moho has been constrained at a depth of 30 km in a small region of the central part of the model, whereas the Iberian Moho has been imaged in its northernmost edge dipping northwards to a depth of 45-50 km.

[en] The argentiferous lead mines of S’Argentera in Ibiza (Balearic Islands, Spain) are some abandoned underground workings from the first decade of the 20th century. The stability of the main stopes and the crown pillar of the mines has been evaluated - part of which is located below the road between Santa Eulalia and San Carles de Peralta. The possibility of allowing public access to the surface of the mining area and setting up a project of a “show mine” on the underground stopes and galleries is analysed. The stability is assessed with an empirical approach using the O index, the scaled span method and a stability graph together with a numerical approach. Results show that the stopes of the mines are globally stable but some lack an adequate safety factor. Therefore some local reinforcements and monitoring are needed. The finite element modelling in two dimensions yields realistic results on the current stope stability and possible rock falls which have already occurred.

[en] Shrimp trawl fishing is a relevant activity that contributes significantly to the generation of economic resources for Ecuador through the creation of jobs and the commercialization of the shrimps. Unfortunately the high variability of the marine ecosystem signals are complex making forecasting a difficult task. This paper evaluates the use of singular spectrum analysis (SSA) for improving forecasting by conventional methods. SSA is implemented in four steps, embedding, decomposition, grouping, and diagonal averaging. The effective length of the embedding window is selected by means of the information provided by the differential energy of the eigenvalues. The SSA decomposition is used to extract two types of components, one of low frequency which represents the inter-annual component, and the other of high frequency which represents the annual component. Once the components have been obtained, three models based on SSA are implemented, the first is based on the autoregressive model (SSA-AR), the second is an artificial neural network (ANN) based on the Levenberg-Marquardt algorithm (SSA-ANN-LM), and the third is another ANN based on the Cuckoo Search algorithm (SSA-ANN-CS). The historical data that was used to evaluate the models are the shrimp monthly catches in the Gulf of Guayaquil from 2000 to 2012. The empirical results show the superiority of the proposed models with respect to the conventional models. The best approximation was achieved with the enhanced model SSA-AR, with a MAPE of 1.0%, a R2 of 99% and a RMSE of 1.5%.

[en] Geologists, economists, policy analysts, and others use two different mental models when assessing depletion and the future availability of mineral commodities. The first, the physical view, relies on estimates of the available exploitable stocks of resources and the speed with which society is likely to consume them. The second, the economic view, uses as its measure of availability differences and trends in real (inflation-adjusted) commodity prices. This paper examines these two approaches, highlighting the very different implications that they suggest for the nature of depletion, its future threat, and the most effective public policies for coping with this threat. After exploring the shortcomings of each, the paper concludes that the economic view is, for several reasons, the more useful and helpful for understanding mineral depletion and its threat.

[en] The Riás Schists crop out in the so-called Iberian Variscan parautochthon, surrounding the Malpica-Tui Complex (NW Iberian Massif), as part of the westernmost internal areas of the European Variscan belt. Three Variscan metamorphic events have been identified in the Riás Schists (M1, M2 and post-M2). M1 comprise unoriented microinclusions that have only been identified in garnet porphyroblast cores and inside staurolite crystals. M2, comprises the matrix foliation (S2) and the assemblage garnetRIM + staurolite + muscovite + biotite + chlorite + rutile/ilmenite + magnetite + quartz and the development of syntectonic andalusite. Finally, postM2 (post-S2) includes andalusite and plagioclase together with secondary muscovite, biotite and chlorite and accessory tourmaline, Fe/Ti oxides, apatite and carbonate. Results of multi-equilibrium thermobarometry (pressure-temperature pseudosections), for M2 indicates a medium-pressure Barrovian metamorphic event (0.5-0.6 GPa; 580-570 o C; ca. 20 km deep), followed by moderate cooling during decompression, together with the extensional collapse of the Variscan orogenic pile (post-M2; 0.3 GPa; 540 o C; ca. 10 km deep). Inferred P T conditions in the Riás Schists, and their spatial relationship with the overlying allochthonous high-pressure pelitic schists (i.e. Ceán Schists), suggest that both lithologies were part of the same continental margin during the beginning of the Variscan orogeny. However, they experienced very different ectonothermal evolutions due to their putative locations in the orogenic wedge.

[en] Modern models of sustainable economic growth are metal-intensive and will not be successful in the future unless a continuous supply of mineral-derived products is ensured. Despite this being logical, there is still a significant reluctance regarding mineral exploration and mining activities, often reflected in: (i) unfavourable public opinions; and (ii) absence of political measures or continuity of agendas that actually appreciate the way minerals are produced and the players directly or indirectly involved in this production. To succeed, the MINERAL INdustry will have to (re)define its strategy and find innovative approaches to old problems and clearly demonstrate that mineral products can be efficiently delivered to support global development and assist suitable paths to welfare and quality of life, thus also providing real value to all concerned. In this study we give a concise review of the main challenges posed to the MINERAL INdustry, and also indicate the most relevant opportunities and advance some proposals to constructively face the identified weaknesses and threats. The fundamental outcome is that the long-term balance between supply and demand of mineral products requires concerted actions on different fronts aiming: (i) the safeguarding of known resources; (ii) high-quality (scientifically and technologically driven) exploration surveys; (iii) improvements in mining and mineral transformation/ beneficiation; (iv) advances in consistent combinations of primary and secondary sources of raw materials, along with higher concerns on their judicious use; (v) effective and stable mining policies; and (vi) new insights on the role played by the MINERAL INdustry through fruitful dialogues with society in general.

[en] Deformation in convergent boundaries of lithospheric plates is localized at the interface between the plates, above the seismic zone of Wadati-Benioff (Isacks et al., 1968). The main triggering candidate for strain localization is the water circulation along this cold zone of a convergent plate boundary (e.g. Peacock, 1990; Bebout, 1991; van Keken et al., 2011; Wada et al., 2012). The cooling by advection and by endothermic reactions of dehydration give rise to temperatures low at high pressure conditions (HP/LT metamorphism). The rheological behaviour of this area is the key to the understanding of the processes of tectonic subduction and exhumation, and in the classical rheological models (e.g. Ranalli, 1995) the plate interface is portrayed as a thin shear zone, where strength failure is defined by Byerlee’s rule (Byerlee, 1978). Current thermo-mechanical models calculate the temperature of a subduction zone based on the advection of the subducted cold plate and help to predict the geometry and rheological evolution of the interface (e.g. Peacock, 1996; Hacker et al.; 2003; Beaumont et al., 2009; Burov et al., 2014a, b). These models take into account the plate age, convergence rate, mineral phase transformations and radiogenic and/or shear heating production during subduction and exhumation. Despite the increasing number of HP/LT terrains, related to different orogens (e.g. Guillot et al., 2009; Ota and Kaneko, 2010), these exhumed terrains generally represent only a small fraction of the subducted lithosphere. The study area is a part of the Caribbean tectonic mélange (Fig. 1) and has been interpreted as generated in a subduction channel (i.e. Krebs et al., 2008, 2011; Hattori et al., 2010; Escuder-Viruete et al., 2011a). This interpretation is based on the P-T-t path in metamorphic rocks, deduced from detailed petrological studies in high pressure basic and ultrabasic blocks. The tectonic evolution is consistent with thermo-mechanical behaviour in numerical models. It is unquestionable that numerical simulations of channel flow have allowed the explanation of the geometry and the metamorphic and geophysical characteristics of most of the collision orogens with reasonable reliability and moreover, the explanation of the existence of some first order geodesic anomalies such as the Tibetan plateau (e.g. Beaumont et al., 2001; Beaumont et al., 2009). However, in detail there are some differences about how the exhumation of high pressure and low temperature rocks is envisaged. The first model in this respect was developed to explain the exhumation of high pressure blocks embedded in an intense deformed matrix in the Franciscan mélange in California (i.e. Cloos, 1982; Cloos and Shreve, 1988a, b). Later models explained the exhumation of high pressure rocks by extension and erosion in an orogenic wedge (i.e. Platt, 1993; Ring et al., 1999). The extensional models had great acceptance in the nineties, however they involved low exhumation rates, and consequently an intense retrogradation of the exhumed terrains may be expected. The collisional thermo-mechanical models of rigid subduction channels (i.e., Gerya et al., 2002; Beaumont, 2009) are nowadays not accepted since they present physical inconsistences (Burov and Yamato, 2008; Burov et al., 2014a).

[en] This paper describes a system of extensional faults oriented NW-SE, NNW-SSE and ENE-WSW responsible for the tectonic relief of semi-grabens in southeastern Dominican Republic. These faults constitute the natural extension of a previously recognized fault system in western Puerto Rico and the Mona Passage. Paleostress analysis carried out on the faults and fractures in the Pliocene limestone results in a minimum NE-SW stress axis, changing to SSW in the faults that affect the Pleistocene limestone. In contrast, the inversion of focal mechanisms of deep, intermediate and shallow earthquakes provides a mechanism characteristic of pure thrust, oblique thrust, strike-slip and normal. Extension in the upper part of the Caribbean crust is accompanied by vertical movements of uplift and subsidence that deform the Plio-Pleistocene coral platform. These movements have been modelled as a broken elastic plate flexed to the trench and incorporated in a more general model of necking in the subducted Atlantic slab. Nevertheless, the flexural mechanism alone can hardly explain the regional extension observed, which is better explained as diffuse rifting, maybe due to the continuity at low rate of the counterclockwise rotation of Puerto Rico.

[en] After the Haiti quake of 2010 an initiative started to better understand shaking effects in the Dominican Republic after natural earthquakes, in particular in the city of Santiago de los Caballeros, the second city in the country as far as inhabitants and economic wealth are concerned. Santiago has suffered several devastating earthquakes; in 1562 the city was rebuilt on a new site (the current location) further south from the responsible fault. It is well known that damage caused by an earthquake occurs associated to a number of factors, ground acceleration is one of them and is usually considered as the key to explain most of the damage. Ground acceleration varies from one point to another depending mainly on: distance to the source of the rupture, soil properties and topography. Regarding the distance, the further from the source the less acceleration is expected due to distance attenuation. On the other hand, different soil properties and different topographies will produce different responses to the propagating wave. Within the range of a few kilometres, the effect of distance attenuation might be far less relevant than the effect of the varying properties of soils. This paper gathers together results obtained from the seismic hazard and microzonation studies developed in the city of Santiago: i) quantification of regional seismic hazard dominated by the Septentrional fault, ii) a new geological mapping of superficial formations, and iii) mapping of zones of homogeneous seismic response and liquefaction susceptibility.

[en] In a context dominated by the rivalry between Spain and Morocco for the Western Sahara, the Spanish state, through the Spanish National Institute of Industry (INI), decided in 1969 to continue with the project initiated by Enminsa in the mining extraction centre of Bu-Craa by creating a new company: Fosbucraa. In this paper, I intend to analyze the financial and technical difficulties of Fosbucraa went through, its business strategy in the phosphate world market and the harmful consequences that the fast withdrawal of Spain from Sahara had on society. I argue that, despite solving all their problems in a short period of time, the development of the company was thwarted due the armed conflict between Morocco and the Polisario Front, and the beginning of a period marked by the fall in international prices of phosphate, which caused the paralysis of the mining activity in the following years.