Along his history the Lower Tagus Valley (LTV) region was shaken by several earthquakes, some of them produced in large ruptures of offshore structures located southwest of the Portuguese coastline. Among these is the Lisbon earthquake of 1 November 1755 (M∼8.5-8.7), and other moderates earthquakes that were produced by local sources such as the 1344 (M6.0), 1531 (M7.1) and 1909 (M6.0) earthquakes. Previous sim...
Throughout its history the Lower Tagus Valley (LTV) has been struck by several earthquakes which produced important material damage and loss of lives: The 1st of November 1755 Lisbon earthquake and the 1969 earthquake (Mw=7.3), located in the SW Iberia Margin and the 1344, 1531 and 1909 (M= 6 to 7) with epicenter located inside the LTV basin. Since this region is the most highly populated region in Portugal, it...
Neste trabalho é apresentada uma metodologia baseada no cruzamento de técnicas e dados sísmicos (ondas de volume com registo telessísmico por estações de banda larga) e geodésicos (SAR - Radar de Abertura Sintética) com o intuito de estudar o complexo processo de ruptura do sismo do Haiti de 12 de Janeiro de 2010. Esta metodologia baseia-se: 1) na análise da diretividade para estimar a direção e a velocidade mé...
ABSTRACT Several tributaries of the Tejo and Zêzere rivers show a graded relict profile in the most upstream reach and a rejuvenated profile in the lower reach. A major slope break in the long profile (knickpoint) separates both reaches. Extrapolation of the oldest graded relict profile downstream to the confluence allowed the incision amount to be quantified. Results reveal that the downcutting is higher in st...
Neste trabalho apresenta-se uma síntese sobre a relevância dos knickpoints na estruturação do perfil longitudinal dos rios e indirectamente, na evolução da paisagem. Aborda-se o significado dos knickpoints relativamente aos conceitos de equilíbrio e desequilíbrio do perfil longitudinal, difundidos na literatura. Leis que regem a incisão fluvial, testadas em modelos físico-matemáticos, estabelecidos nas duas últ...
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