Loading...
5 results
Search Results
Now showing 1 - 5 of 5
- Estruturas mediterrânicas tradicionais. A utopia da paisagem urbano-turística do AlgarvePublication . Bragança, Carlos; Marçal Gonçalves, Marta; Prates, Gonçalo Nuno DelgadoUma das características marcantes das paisagens mediterrânicas é a armação dos terrenos montanhosos em socalcos suportados por muros de pedra seca. Além do carácter identitário que imprimem na paisagem, as construções milenares em pedra seca estabelecem uma rede de compartimentação com várias funções ou utilidades, como suporte de terras, drenagem, armazenamento de águas, divisão de propriedade, limitação de caminhos e veredas. Para além destas funções, focar-nos-emos de forma especial nos valores sociais e éticos capazes de gerar alternativas de evolução da paisagem. No Algarve, se bem que os valores atribuídos pelas populações locais sejam determinantes nessa evolução, o papel dos turistas e população residente estrangeira pode, no entanto, ser fundamental para gerar novos contextos cénicos. O nosso argumento gira em torno do futuro da estrutura dos muros de pedra seca, a prospetar dentro da diversidade de possíveis soluções sobre o desenvolvimento da paisagem envolvente do sistema urbano, enquanto parte viva de uma unidade que inclui as áreas mais densamente urbanizadas. Designamos essa unidade região urbanoturística do Algarve, inspirada em duas referências utópicas: a de ‘região urbana’ e a de ‘agropólia’, em que a paisagem é assumida como bem comum e instrumento de conhecimento e reconhecimento –governança democrática– de espaços regionais.
- Geodetic implications on block formation and geodynamic domains in the South Shetland Islands, Antarctic PeninsulaPublication . Berrocoso, M.; Fernandez-Ros, A.; Prates, Gonçalo; Garcia, A.; Kraus, S.The South Shetland Islands archipelago is dynamically complex due to its tectonic surroundings. Most islands are part of a formerly active volcanic arc, although Deception, Penguin and Bridgeman Islands, as well as several submarine volcanoes, are characterized by active back-arc volcanism. Geodetic benchmarks were deployed and the movement of the lithosphere to which they were fixed measured to provide geodynamic insight for the South Shetland Islands, Bransfield Basin and Antarctic Peninsula area based on surface deformation. These benchmarks' data add spatial and temporal coverage to previous results. The results reveal two different geodynamic patterns, each confined to a distinct part of the South Shetland Islands archipelago. The inferred absolute horizontal velocity vectors for the benchmarks in the northeastern part of the archipelago are consistent with the opening of the Bransfield Basin, while benchmark vectors in the southwestern part of the archipelago are similar to those of the benchmarks on the Antarctic Peninsula. In between, Snow, Deception and Livingston Islands represent a transition zone. In this area, the horizontal velocity vectors relative to the Antarctic plate shift northeastwards from N to NW. Furthermore, the South Shetland Islands benchmarks, except for that at Gibbs (Elephant) Islands, indicate subsidence, which might be a consequence of the slab roll-back at the South Shetland Trench. In contrast, the uplift revealed by the Antarctic Peninsula benchmarks suggests glacial isostatic adjustment after the Larson B ice-shelf breakup. (C) 2015 Elsevier B.V. All rights reserved.
- Normal vector analysis from GNSS-GPS data applied to Deception volcano surface deformationPublication . Berrocoso, M.; Prates, Gonçalo; Fernandez-Ros, A.; Garcia, A.Surface deformation parameters and its use in volcano monitoring have evolved from classical geodetic procedures up to those based on Global Navigation Satellite Systems (GNSS), in particular the most widely used and known Global Positioning System (GPS), profiting from the automated data processing, positioning precision and rates, as well as the large storage capacity and low power consumption of its equipments. These features have enabled the permanent GNSSGPS data acquisition to ensure the continuous monitoring of geodetic benchmarks for the evaluation of surface deformation in active tectonic or volcanic areas. In Deception Island (Antarctica), a normal vector analysis is being used to give surface deformation based on three permanently observed GNSSGPS benchmarks. Due to data availability, both in the past and for near real-time use, all benchmarks used are inside the monitored volcanic area, although the reference is away from thermal springs and/or fumaroles, unlike the other two. The time variation of slope distances to the reference benchmark and of the magnitude and inclination of the normal vector to the triangle defined by the reference benchmark and any other two, provides the spatial deformation in the volcanic area covered. The normal vector variation in magnitude gives information on compression or expansion, here called spatial dilatometer, while the changes in inclination gives information on relative uplift or subsidence, here called spatial inclinometer. In geodesy, the triangle is a basic geometric unit and the areal strain is commonly applied in tectonics and volcanism. The normal vector analysis conjugates both, benefiting from the method's precision, simplicity and possibility to model the surface using several triangles. The proposed method was applied to GNSSGPS data collected every austral summer between 20012002 and 20092010 in Deception Island. The results evidence that Deception Island acts as a strain marker in the Bransfield Basin volcano-tectonic setting.
- Volcano-tectonic dynamics of Deception Island (Antarctica): 27 years of GPS observations (1991-2018)Publication . Rosado, B.; Fernandez-Ros, A.; Berrocoso, M.; Prates, Gonçalo; Garate, J.; de Gil, A.; Geyer, A.Deception Island (South Shetland Islands) is one of the most active volcanoes in Antarctica. In the 1988-1989 austral summer, after the most recent eruptive process on the island (1967-1970), monitoring of volcanic activity through geophysical and geodetic techniques was resumed by Spanish and Argentinean scientists. In order to monitor the island's tectonic and volcanic behavior, a geodetic network was deployed. Currently, this network consists of 15 geodetic benchmarks located around Port Foster, Deception's inner bay open to the sea. Two additional geodetic benchmarks were installed outside Deception Island to be used as reference benchmarks for the differential positioning strategy. Since 1991-1992, geodetic ground-displacement velocities between the successive austral summer Antarctic campaigns have been computed and analyzed. The overall geodynamic behavior of Deception Island within the South Shetland Islands, Antarctic Peninsula and Bransfield Basin regional environment has been analyzed from geodetic ground-displacements. Results obtained demonstrate that Deception and Livingston island have a similar behavior derived from the Bransfield Basin extension and the Phoenix micro-plate subsidence processes. However, Deception Island is also highly influenced by its volcanic activity. Deception Island's volcanic behavior between 1991 and 2018 is shown by the velocity field, strain tensors and pressure source evolution obtained from the ground-displacements at the geodetic benchmarks. During this time period, it is possible to identify different inflation and deflation phases separated by transitional (or mixed) stages of extension without uplift and compression without subsidence. The most representative inflation and deflation periods were analyzed in detail, to show how they correlate with high and low seismic activity, respectively. The transitional or mixed stages, seem to be the precursors of the next inflation or deflation phase being the Bransfield basin rifting and NW-SE extension the potential related process. Finally, we have analyzed the processes that occurred prior to the volcanic unrests of 1999-2000 and 2012-2013. In both cases, an increase in detected seismic activity and/or soil and seawater temperature was observed and a mixed phase of extension without uplift seems to be precursory to the volcanic unrest. The correlation between the inflation processes, identified by ground-displacement of the network geodetic benchmarks, the increase in seismicity and the increment of soil and seawater temperature makes these transitional mixed phases potential precursors of Deception Island's volcanic unrest periods.
- Renewing terraces and drystone walls of Algarvian Barrocal. Cultural and touristic valuesPublication . Marçal Gonçalves, Marta; Prates, Gonçalo Nuno Delgado; Rosendahl, StefanThis paper aims to enhance the functions of terraces and drystone walls as structural elements and distinctive factors of the traditional rural zone known as the barrocal of the Algarve, south of Portugal. In fact, such elements define the character of the landscape that forms the background of a traditional touristic region along the coast. The core of this paper will be the knowledge of construc-tion processes, spatial distribution, and hydrological, ecological, economic and social functions, once it is quite necessary for the Algarve region. Some projects and studies have been developed in the Mediterranean context, but there is not enough research on this subject in the south of Portugal. Secondly, the social meaning, or acknowledgement of the landscape characterized by drystone wall structures, will be the key for finding real possibilities of renewing the terraces. Therefore, the landscape will be assumed as a common good. In this subject, we take into account the potential role and sensibility of tourists and resident popu-lation. Beyond static patrimonial statutes, we can design some practical possibil-ities to enhance plastic features and new uses leading to an acknowledgement of the Algarvian drystone wall structure, referred as a part of Mediterranean coastal landscapes. Some examples that can add cultural and touristic value could be: recreation areas for urbanites, new cooperative forms of agriculture, hobby farm-ing, workshops about harvesting traditional products, circuits and pedestrian paths, and interchange with similar Mediterranean regions defining broader cir-cuits.