Large earthquakes in the Azores

The history of the Azores archipelago, from its discovery and settlement in the rst half of the 15th century through the present, is marked by the social and economic impacts produced by earthquakes, mainly the high-intensity ones. Information that has been compiled leads to the conclusion that in this period, 33 earthquakes with intensity equal to or greater than VII have affected the Azores, which caused approximately 6,300 deaths and widespread destruction on some islands of the archipelago, principally S. Miguel, Terceira, Graciosa, Faial, S. Jorge and Pico Islands. The accommodation of strain resulting from the dynamics of the Azores triple junction (ATJ) plate boundary and volcanism, which also occurs in the region, are the main factors responsible for the intense seismic activity in this archipelago. This work reviews the scienti c issues of the known earthquakes that have severely interfered with the lives of the Azorean people throughout their history, which we call large earthquakes

Workshop em Ciências da Terra e do Espaço - Livro de Atas

O presente livro foi produzido no âmbito da unidade curricular Seminário do programa de Doutoramento em Ciências da Terra e do Espaço (DCTE) e do Mestrado em Ciências da Terra, da Atmosfera e do Espaço (MCTAE), que incluiu a organização da edição de 2018 do Workshop em Ciências da Terra e do Espaço da Universidade de Évora (WCTE2018). Neste volume estão reunidos os artigos de investigação produzidos pelos estudantes que frequentam a referida unidade curricular. O WCTE assume-se, desde a sua primeira edição em 2013, como um espaço de partilha de conhecimento e treino de comunicação em ciência. Nesse sentido, procura proporcionar aos estudantes que frequentam a Unidade de Seminário uma experiência efetiva não apenas na preparação e apresentação de comunicações orais e artigos de investigação, mas também na organização do próprio evento. Na edição do WCTE2018, que ocorreu no dia 10 de janeiro, foram submetidos e apresentados 9 trabalhos, que abrangem as várias temáticas que dos cursos MCTAE e DCTE

Design and Evaluation of a High Throughput Seismic Sensor Network - Tools for Planning, Deployment and Assessment

The rapid technological evolution in sensors, sensor platforms and networking is enabling the deployment of large sensor networks for "live" monitoring of seismic activity with high spatial resolution. In this regard, this paper describes our work in developing an online "High Throughput Seismic Sensor Network". We present the architecture and implementation comprising seismic sensors and servers (running data collection services) connected through internet-enabled technologies. We validate and assess the system, as well as identify bottlenecks, by means of experimentation. Based on the collected empirical data, we were able to identify methods and tools to support effective planning and implementation of sensor networks based on two main indicators: Sensor Network Transmission Rate (SNTR), which provides the overall network sensor data transmission throughput and thus an indication of the required network capacity; and CPU Sensor Network Performance Index (CSNPI), which provides an indication of a server capability to handle network sensor data. As we progress in our work to field deploy seismic sensor networks, we will continue to use these tools to plan and deploy future sensor networks, as well as assess improvements and modifications along the way

Física Geral I

para os cursos de Eng. Civil, Eng. Mecatrónica e Eng. Energias renováveis – conjunto de materiais composto por “Power Point” usados nas aulas teóricas; notas para apoio ao estudo elaboradas a partir das apresentações das aulas teóricas; fichas de exercícios e guias experimentais. Os materiais elaborados abrangem os temas: A Física como Ciência; Oscilações e ondas; Óptica; Termodinâmica; Teoria Cinética dos gases

Áquila Earthquake (2009): influence of seismic source model and structure to modeling the strong ground motions

O sismo, ocorrido em 6 de Abril de 2009 (Mw 6,3) junto à cidade de Áquila (Itália), provocou uma grande destruição. Uma das consequências deste evento foi o impacto na opinião pública em torno da capacidade científica para a estimação da perigosidade sísmica e a necessidade de criação de sistemas de alerta sísmico. A determinação dos mecanismos de fonte sísmica de eventos sísmicos ocorridos e registados permite melhores caracterizações dos movimentos sísmicos para uma determinada área de estudo e consequentemente melhores cenários de risco. Se a região em estudo possuir propriedades físicas específicas e muito distintas de local para local, capazes de provocar alterações locais dos movimentos sísmicos (efeitos de sítio), torna-se imperativo uma caracterização bem definida do meio de propagação das ondas sísmicas de forma a poder sintetizar informação capaz de contribuir para a boa estimação da perigosidade sísmica. No âmbito deste trabalho pretende-se estudar a influência do mecanismo de fonte sísmica e da estrutura na modelação de movimentos sísmicos no caso de Áquila. A metodologia adoptada consiste na determinação da distribuição de deslizamentos sobre o plano de falha e utilização desta informação na modelação de sismogramas sintéticos (com recurso ao algoritmo E3D). Será igualmente estabelecida uma comparação de resultados considerando-se um meio com e sem bacia e considerando-se uma fonte pontual e uma fonte extensa

DIRDOP: a directivity approach to determining the seismic rupture velocity vector

Directivity effects are a characteristic of seismic source finiteness and are a consequence of the rupture spread in preferential directions. These effects are manifested through seismic spectral deviations as a function of the observation location. The directivity by Doppler effect method permits estimation of the directions and rupture velocities, beginning from the duration of common pulses, which are identified in waveforms or relative source time functions. The general model of directivity that supports the method presented here is a Doppler analysis based on a kinematic source model of rupture (Haskell, Bull Seismol Soc Am 54:1811–1841, 1964) and a structural medium with spherical symmetry. To evaluate its performance, we subjected the method to a series of tests with synthetic data obtained from ten typical seismic ruptures. The experimental conditions studied correspond with scenarios of simple and complex, unilaterally and bilaterally extended ruptures with different mechanisms and datasets with different levels of azimuthal coverage. The obtained results generally agree with the expected values. We also present four real case studies, applying the method to the following earthquakes: Arequipa, Peru (Mw = 8.4, June 23, 2001); Denali, AK, USA (Mw = 7.8; November 3, 2002); Zemmouri– Boumerdes, Algeria (Mw = 6.8, May 21, 2003); and Sumatra, Indonesia (Mw = 9.3, December 26, 2004). The results obtained from the dataset of the four earthquakes agreed, in general, with the values presented by other authors using different methods and data

Geophysical prospection of antique structural traces from São Francisco (Évora) Royal Palace with the use of georradar and laser scanner.

In the place where currently there is the D. Manuel Palace, in Évora, will have been the Royal Palace of S. Francisco, one of the residences of the Portuguese monarchy between the sixteenth and seventeenth century. The building began to decline in 1616 and has been adapted to other occupations, abandoned and destroyed by re. Between this building and the market there are archaeological remains, discovered during the execution of urban works. The current building was the result of several changes on what’s left, the last one on the front of its facade, which were removed monumental stairs that there is photographic record. This work intends to show the existence of ancient palace remains, integrated into the structures that currently exist within the research effective methods of application of geophysical techniques in Archaeology. To realize the goal, it proceeded to carry out geophysical prospecting with georadar, in areas adjacent to the palace, and with laser scanner, in order to integrate the results of georadar a three-dimensional representation of the current building. The results show the existence of structures that have corresponded to the palace staircase and remains consistent with the view that the palace would be extended to the side where there is the current market

Strong Ground Motion Simulations and Assessment of Influence of Model Parameters on the Waveforms

Modeling near-field ground motion is an important and useful tool of modern seismology. In our work we use a finite difference algorithm to compute near-field ground motions from a real moderate event with pre-existing slip distribution model. Lately, synthetic seismograms are quantitatively compared with observed waveforms from near-field seismic stations in order to justify created model. Furthermore, we independently changed several source parameters (rupture velocity, source dimension and geometry), and structure (velocity model) in order to evaluate their influence on the waveforms. For the comparison of seismograms we applied quantitative misfit criteria based on wavelet transform

Three-dimensional seismic ground motion modelling in Lower Tagus Valley from Finite difference simulations

Throughout its history the Lower Tagus Valley (LTV) has been struck by several earthquakes which produced important material damage and loss of lives: The 1rst of November 1755 Lisbon earthquake and the 1969 earthquake (Mw=7.3), located in the SW Iberia Margin and the 1344, 1531 and 1909 (magnitudes ranging from 6 to 7) with epicenter located inside the basin. Since this region is the most highly populated region in Portugal, it is expected that an earthquake of similar magnitude of those that have occurred in the past will cause an enormous destruction and casualties. To contribute to an improved assessment of the seismic hazard in the Lower Tagus Basin we introduce a realistic method on the prediction of seismic ground motion produced by moderate to large earthquakes in this area. This process involves the establishment of a structural 3D model, the evaluation of seismic potential of the faults in the studied area, and finally, a three-dimensional seismic ground motion modeling based on Finite Difference Methods. After that, using appropriated relations between seismic intensity (MMI) and PGV we computed the synthetic isoseismic maps. By comparing these results with available seismic intensities it is possible to evaluate the realism of the different proposed sources. This study gives new insights on the seismic risk in LTV and will help to identify the regions that are most exposed to strong ground motions

Mass – Radius Relationship in Extrasolar Planets

The increasing number of Extrasolar planets observed in the last years makes important to define, as soon as possible, a mass – radius relationship, and so, we adjusted an planetary constitution independent experimental equation. Using the latest database of Extrasolar planets, a bi-logarithmic graphic was plotted that represents the mass - radius relationship where we adjusted a polynomial equation, which better suited the sample of Extrasolar planets at current time