Non-invasive Geophysical Surveys in Search of the Roman Temple of Augustus Under the Cathedral of Tarragona (Catalonia,Spain): A Case Study

An integrated geophysical survey has been conducted at the Tarragona’s Cathedral (Catalonia, NE Spain) with the aim to confirm the potential occurrence of archaeological remains of the Roman Temple dedicated to the Emperor Augustus. Many hypotheses have been proposed about its possible location, the last ones regarding the inner part of the Cathedral, which is one of the most renowned temples of Spain (twelfth century) evolving from Romanesque to Gothic styles. A geophysical project including electrical resistivity tomography (ERT) and ground probing radar (GPR) was planned over 1 year considering the administrative and logistic difficulties of such a project inside a cathedral of religious veneration. Finally, both ERT and GPR have been conducted during a week of intensive overnight surveys that provided detailed information on subsurface existing structures. The ERT method has been applied using different techniques and arrays, ranging from standard Wenner–Schlumberger 2D sections to full 3D electrical imaging with the advanced Maximum Yield Grid array. Electrical resistivity data were recorded extensively, making available many thousands of apparent resistivity data to obtain a complete 3D image after a full inversion. In conclusion, some significant buried structures have been revealed providing conclusive information for archaeologists. GPR results provided additional information about shallowest structures. The geophysical results were clear enough to persuade religious authorities and archaeologists to conduct selected excavations in the most promising areas that confirmed the interpretation of geophysical data. In conclusion, the significant buried structures revealed by geophysical methods under the cathedral were confirmed by archaeological digging as the basement of the impressive Roman Temple that headed the Provincial Forum of Tarraco, seat of the Concilium of Hispania Citerior Province.     

Scientific management of Mediterranean coastal zone: a hybrid ocean forecasting system for oil spill and search and rescue operations

The oil spill from Prestige tanker showed the importance of scientifically based protocols to minimize the impacts on the environment. In this work, we describe a new forecasting system to predict oil spill trajectories and their potential impacts on the coastal zone. The system is formed of three main interconnected modules that address different capabilities: (1) an operational circulation sub-system that includes nested models at different scales, data collection with near-real time assimilation, new tools for initialization or assimilation based on genetic algorithms and feature-oriented strategic sampling; (2) an oil spill coastal sub-system that allows simulation of the trajectories and fate of spilled oil together with evaluation of coastal zone vulnerability using environmental sensitivity indexes; (3) a risk management sub-system for decision support based on GIS technology. The system is applied to the Mediterranean Sea where surface currents are highly variable in space and time, and interactions between local, sub-basin and basin scale increase the non-linear interactions effects which need to be adequately resolved at each one of the intervening scales. Besides the Mediterranean Sea is a complex reduced scale ocean representing a real scientific and technological challenge for operational oceanography and particularly for oil spill response and search and rescue operations.     

Rainfall spatial organization and areal reduction factors in the metropolitan area of Barcelona (Spain)

The rainfall spatial organization in the metropolitan area of Barcelona (Spain) has been studied from records of an urban rain gauge network in the period 1994–2009. Using statistical and regional analysis techniques, correlation between data recorded by the different rain gauges has been calculated, and the effective number of independent stations (n _eq) equivalent to the used network has been determined. It has been found out that for durations longer than 20 min, the areal rainfall return period observed for a storm registered by the network approximately decreases by a factor of 1/n _eq in relation to the current point rainfall intensity–duration–frequency relationships for the metropolitan area of Barcelona. Using objective analysis techniques, continuous precipitation fields have been generated on a regular grid with a spatial resolution of 300?×?300 m for the storms registered by the rain gauges from 1994 to 2009, for durations from 10 min to 24 h. The precipitation fields obtained have been useful to estimate the characteristic areal reduction factors in the metropolitan area of Barcelona. A direct relationship has been found between the areal reduction factor for all the area corresponding to the urban rainfall network of Barcelona and the effective number of n _eq for every duration considered.     

The Baraza Slide: model and dynamics

The Baraza Slide is located in the northwestern Alboran Sea, western Mediterranean region, between 590 and 830?m water depth, and its morphology, seismic facies and sedimentary structure are analyzed based on multibeam bathymetry and very high to medium resolution single-channel seismic records. During the Pleistocene and Late Quaternary this landslide has undergone repeated slope failures characterized by a succession of two main types of mass movement, the first of the mass-flow type and the second of the slide type. This study also reveals that the western sector of this landslide could still be active. The relatively high slope gradients, a sedimentary column characterized by the presence of under consolidated layers and earthquake shaking related to tectonic activity on the margin are the factors governing the genesis and post-mobility behavior of the Baraza mass movement. The recognition and analysis of these factors suggest that the Baraza Slide should be considered as a geo-hazard in the tectonically active Alboran Sea.     

Full-scale dynamic testing of the Alamillo cable-stayed bridge in Sevilla (Spain)

Accelerations and displacements due to dynamic excitation by simulated traffic consisting of two trucks, were measured on the deck and tower of the Alamillo cable-stayed bridge. Also the dynamic testing program included the measurement with accelerometers of the free-damped vibration of the 26 cables achieved by means of quick-releasing force. From these measurements it was possible to obtain the dynamic parameters of the bridge (natural frequencies and damping ratios) and the real forces in the cables. In the paper, only the tests, results and conclusions related to dynamic parameters of the bridge are presented. The objective of the dynamic tests herein described was to validate the mathematical modelling and the wind-tunnel models used in the dynamic analysis of the bridge in front of traffic and wind-forces. As the agreement between dynamic parameters of the real bridge and theoretical and scaled models was very satisfactory, the correct dynamic behaviour of the bridge in response to traffic and wind (vortex shedding, flutter, etc.) can be deduced jointly with the correct alignment and expected internal forces in the permanent state in tower and deck.     

Evidence of a Cretaceous remagnetization in the Cameros Basin (North Spain): implications for basin geometry

The paleomagnetic results obtained in 23 sites from red beds of the northern border of the inverted Cameros Basin (northern Iberian Peninsula) prove a Cretaceous widespread remagnetization. Paleomagnetic and rock magnetic analyses indicate that the Natural remanent magnetization (NRM) is dominated by a stable and always normal polarity component carried by haematite. Two conglomerate test and five-fold test indicate that this component is a syn-tectonic overprint dated between Albian and Santonian times, most probably Albian, contemporary with a low-grade metamorphism. Remagnetization was acquired before compressional deformation and post-dates the main extensional stage of basin formation (Berriasian–Albian). Incremental fold tests provide best clustering solutions showing dispersed results and far from the expected direction. An alternative procedure to obtain fold test solution was applied considering asymmetric limb rotation. Mean directions obtained from these “asymmetric solutions” are consistent with the expected direction and yield a statistical value for significant grouping at the 95% confidence level in all fold tests performed. This reconstruction allows to determine the tilting of beds at the moment of acquisition of magnetization. These original dips were used to reconstruct the original geometry of the northern basin border, later modified during the Tertiary inversion stage. This extensional geometry can be characterised as a large-scale syn-sedimentary normal fault drag, with a minor roll-over anticline. The procedure developed in this paper should be tested in other inverted basins that also have undergone burial remagnetizations.     

Geographic characteristics of a network interdiction problem

The protection of critical infrastructure from natural and intentional events is a key component of any national security agenda. Protection schemes need to be readily identifiable and adaptable to complex changing environments. In this paper, we identify strategic geographic characteristics that impact the location of detection resources (e.g. sensors) towards the defense of regional critical infrastructure. Specifically, we seek to estimate the relationship between the results of a variation of the traditional shortest path network interdiction problem and geographical characteristics of the transportation infrastructure and the urban environment. Experiments conducted on three distinct transportation networks of different shapes and granularities (New York City—grid, Houston—radial, Boston—hybrid) underline the importance of geographic characteristics such as the proximity to resource location, attacker entry points as well as network coverage. Insights gained from this work are relevant to policy and decision makers to facilitate the development of analytical and decision-support tools capable of identifying resource allocation strategies. We discuss a heuristic-based framework that prioritizes the selection of detection resources, reflecting the importance of geographic characteristics. The findings underline the importance of geographical characteristics for the allocation of resources in a regional setting.     

Processing Symplectic Methods for Near-Integrable Hamiltonian Systems

Processing techniques are used to approximate the exact flow of near-integrable Hamiltonian systems depending on a small perturbation parameter. We study the reduction of the number of conditions for the kernel for this type of Hamiltonians and we build third, fourth and fifth order methods which are shown to be more efficient than previous algorithms for the same class of problems. This revised version was published online in July 2006 with corrections to the Cover Date.     

Role of lateral thickness variations on the development of oblique structures at the Western end of the South Pyrenean Central Unit

The Montsec unit is one of the most important detached South-verging nappes within the South Pyrenean Central Unit (SPCU, Southern Pyrenees). A N–S cross-section of its Western sector, based on seismic reflection profiles, shows a hangingwall ramp geometry in Mesozoic strata, overlain by a syntectonic series of Lower Eocene sediments with growth geometry. The geometry of growth strata constrains the age of its movement between the Paleocene and the Middle Eocene. The geometry of the Western, oblique ramp of the South Pyrenean Central Unit is defined by a series of N–S folds, in some cases associated with underlying West-verging thrusts, as indicated by seismic reflection profiles and field data. In this paper, we propose that the geometry of the thrust wedge of Mesozoic units, progressively thinning from East to West, strongly contributed to constrain the location and geometry of the Western termination of the Montsec thrust. The hypothesis proposed is checked by a series of experimental wedges developed in a sandpack with lateral and three-dimensional thickness variations. Oblique structures form as thrusting progresses at the tip of the sand wedge.