The Spanish Central System is a Cenozoic pop-up with an E W to NE SW orientation that affects an the crust (thick-skinned tectonics). It shows antifonn geometry in the upper crust with thickening in the lower crust. Together -with the Iberian Chain it constitutes the most prominent mmmtainous structure of the Pyrenean foreland.The evolutionary patterns concerning the paleotopography of the interior of the Peninsula can be established by an analysis of the fo11owing data: gravimetric, topographical, macro and micro tectonic, sedimentological (infilling of the sedimentary basins of the relative foreland), P T t path from apatite fission tracks, paleoseismic and instrumental seismicity.Deformation is dearly asymmetric in the Central System as evidenced by the existence of an unique, large (crustal-scale) thrust at its southern border, while in the northern one there is a normal sequence of north verging thrusts, towards the Duero Basin, whose activity ended during the Lower Miocene. This deformation was accomplished lUlder triaxial compression, Oligocene Lower Miocene in age, marked by NW SE to NNW SSE shortening. Loca11y orientations of paleostresses deviate from that of the regional tensor, follo-wing a period of relative tectonic quiescence. During the Upper Miocene Pliocene, a reactivation of constrictive stress occurred and some structures underwent rejuvenation as a consequence of the action of tectonic stresses similar to those of today (lUliaxial extension to strike slip -with NW SE shortening direction). However, the westernmost areas show continuous activity throughout the whole of the Tertiary, with no apparent pulses. At the present time there is a moderate seismic activity in the Central System related to faults that were active during the Cenozoic, with the same kinematic characteristics.

We infer that the Alboran Basin, the first western Mediterranean Basin found after crossing Gibraltar, is an orogenic float underlained by a de´ collement system, a multi-layered ductile shear extending from 10 km to between 30 and 40 km below sea level. This float was formed as consequence of the collision of the African-Eurasian plates in the Oligocene-late Miocene. Synchronous with this compression the float experienced basin wide crustal thinning and subsidence about 25 m/year ago by subcrustal processes. Since latest Miocene the float has undergone compression due to the continuous convergence of Eurasia and Africa. The faults created as a result of this compression are dominated by a conjugate system of northeast trending left-lateral and northwest right-lateral strike-slip faults. This deformation is taking place under a simple shear mechanism. Associated with the northwest and northeast lateral faults are zones of compression trending west and east of north extending from the base of the basin's north upper slope to the Alboran Ridge. The initial morphology of the Alboran Ridge on the southern side of the Alboran Basin was due to the construction of a volcanic edifice at the northeast end of the ridge and igneous activity along northeast trending fractures southwest of the edifice. At the northeast end of the Alboran Ridge motion along a right-lateral fault cutting across the ridge led to sediment collapse and the creation of a prominent embayment on the ridge's northwest flank. Deformation is more subdued in the western than in the eastern part of the Alboran Basin, a tectonic style due either to differences in sediment rheology or that the accommodation of the convergence of Africa and Iberia is more diffused and attenuated in the west than in the east.

Deception Island is a young, active volcano located in the south-western part of Bransfield Strait, between the Antarctic Peninsula and the South Shetland archipelago. New gravity and magnetic data, from a marine geophysical cruise (DECVOL-99), were analysed. Forty-eight survey lines were processed and mapped around Deception Island to obtain Bouguer and magnetic anomaly maps. These maps show welldefined groups of gravity and magnetic anomalies, as well as their gradients. To constrain the upper crustal structure, we have performed 2+1/2D forward modelling on three profiles perpendicular to the main anomalies of the area, and taking into account previously published seismic information. From the gravity and magnetic models, two types of crust were identified. These were interpreted as continental crust (located north of Deception Island) and more basic crust (south of Deception Island). The transition between these crustal types is evident in the Bouguer anomaly map as a high gradient area trending NE-SW. Both magnetic and gravity data show a wide minimum at the eastern part of Deception Island, which suggests a very low bulk susceptibility and low density intrusive body. With historical recorded eruptions and thermal and fumarolic fields, we interpret this anomaly as a partially melted intrusive body. Its top has been estimated to be at 1.7 km depth using Euler deconvolution techniques.

As part of a systematic mapping program of the Hydrographic and Oceanographic Research Plan for the Spanish Exclusive Economic Zone (EEZ), gravity surveys were carried out offshore the Canary Islands. Using the gravity data collected during cruises between 1998 and 2000 aboard the RV Hesperides and satellite and land data, we construct free air and Bouguer anomaly maps and discuss the geodynamic implications.Using maps of Bouguer anomaly, free air anomaly, vertical derivative, long wavelength Bouguer anomaly and short wavelength anomaly, a detailed description of the gravity characteristics of the archipelago is presented, describing gravity anomalies from a geologic point of view. The character of the crust throughout the studied area has been defined, as well as high gradient zones that limit crustal blocks of different density. High gradient zones have been mapped for the first time and interpreted as fracture zones, taking into account geophysical and geological information. Gravity highs and lows have been studied and related to crustal, mantle and volcanic effects.

A complete multibeam coverage of the sea floor of Mallorca Channel, in the western Mediterranean, was recorded during the Spanish Exclusive Economic Zone surveys in 1995, 1996 and 1997. These data, combined with previous high-resolution seismic reflection profiles, allow an assessment of the geomorphology of the area. The channel seafloor is disrupted by a fault complex and pockmarks. Motion along the faults split the sea floor into a series of undulations separated by narrow V-shaped notches. Faulting may be a consequence of recent seaward gravitational sliding that occurred along a soft surface at the top of a late Messinian -early Pliocene unit and a late Messinian evaporite. These units have been tilted during recent subsidence of the Mallorca Channel at the same time that the insular shelf was uplifted along a fault at the shelf's edge. The set of pockmarks in the channel sequence were probably formed by the expulsion of gas of hydrothermal origin, and expulsion may have been enhanced by the faulting. This gas seepage could be an additional factor leading to sediment instability. D