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- On the source of the 8 May 1939 Azores earthquake - tsunami observations and numerical modellingPublication . Reis, Cláudia; Omira, Rachid; Matias, Luis; Baptista, Maria Ana Carvalho VianaOn 8 May 1939, an earthquake (Ms7.1) occurred near the Azores archipelago, with an epicentre located close to the western end of the Gloria fault. Previous studies present different epicentre locations spreading over a large area, and two different types of focal mechanisms. Given these uncertainties, the interpretation of the seismological information in a complex tectonic environment between the Gloria Fault and the Terceira Ridge is a matter of debate. The event caused a small tsunami recorded in the Azores Islands. In this study, we use the tsunami observations and tsunami numerical modelling to select the earthquake fault rupture that best fits the tsunami observations. We consider the different focal mechanism solutions, perform tsunami numerical modelling, and compute synthetic tsunami waveforms at the tide gauge locations. We find that an earthquake caused by a low-angle dipping fault with dominant strike-slip movement generates a tsunami that reproduces well the record at Ponta Delgada tide gauge. Finally, in areas where earthquakes are rare, the study of ancient earthquakes must use all information available, namely tsunami observations and mareograph data.
- Mammography equipmentPublication . Sechopoulos, Ioannis; Reis, CláudiaMammography is one of the most technically demanding examinations in radiography. The requirements of imaging very small calcifications at the same time as low-contrast masses, at very low doses suitable for screening, have placed great demands on this imaging technology. This has resulted in the development of radiographic equipment dedicated specifically for breast imaging. In addition, the advent of digital detector technology has resulted in the pursuit of multiple new X-ray imaging modalities for breast imaging, all trying to address one or several limitations of standard mammography. In all, the last 30 years have seen exciting developments of new equipment, both for mammography and its derivatives. The fact that important innovations continue to be pursued is a testament to the extreme demands posed for this imaging task. This chapter will overview this equipment.
- Experimentally validated numerical models to assess tsunami hydrodynamic force on an elevated structurePublication . Reis, Cláudia; Clain, Stéphane; Figueiredo, Jorge; Barbosa, Andre R.; Baptista, Maria Ana Carvalho Viana; Lopes, MárioRecently, the North American and Japanese authorities began combining the tsunami forces with other loads in their structural design guidelines. Nonetheless, due to the infrequent nature of tsunamis, the provisions may benefit from complementary insights on the qualitative and quantitative characterization of the extreme phenomena and their interaction with coastal structures. The goal of this paper is to explore reliable and relatively accessible computational techniques to determine pressures and forces due to tsunami-like waves on elevated structures. Hydrodynamic flow quantities are simulated for the tsunami-like waves using an Eulerian scheme (Shallow Water equations solved by the Finite Volume method), a Lagrangian scheme (Navier-Stokes equations solved by the Smoothed Particle Hydrodynamics method), and a coupled Eulerian Lagrangian modeling approach. The numerical solutions are validated against experimental data acquired from an experimental campaign performed at the large wave flume of the Hinsdale Wave Research Laboratory, Oregon State University. The correlations between the experimental data and the numerical solutions highlight the advantages and disadvantages of the simulation techniques used, contributing to increase the confidence levels in their use in determining tsunami forces for use in structural assessments and design.