Reis, C., Barbosa, A. R., Figueiredo, J., Clain, S., Lopes, M, & Baptista, M. A.. (2022). Smoothe... more Reis, C., Barbosa, A. R., Figueiredo, J., Clain, S., Lopes, M, & Baptista, M. A.. (2022). Smoothed particle hydrodynamics modeling of elevated structure impacted by tsunami-like waves. Engineering Structures, 270, 114851. DOI:10.1016/j.engstruct.2022.114851
International Journal of Disaster Risk Reduction , 2022
Preventive management strategies are evolving towards multi-hazard risk estimates. Commonly, the ... more Preventive management strategies are evolving towards multi-hazard risk estimates. Commonly, the multi-hazard characterization is pursued following a probabilistic approach. However, scenario-based evaluations can provide complementary key insights of relevance to design critical facilities. In this paper, an alternative deterministic analysis was explored to characterize the cascade seismic and tsunami actions of a 1755-alike Great Lisbon Earthquake and Tsunami event oriented to the container terminal of Sines deep-water seaport, Portugal, which is in expansion to increase the current 2.3 million TEU capacity to 7.1 million TEU. The analysis accounts source, propagation and site effects uncertainties influencing the multi-hazard estimates for different structural configurations representing the different stages of the extension plans for the infrastructure. The target-hazard assessment assumes ground motion acceleration and tsunami hydrostatic and hydrodynamic quantities as explanatory variables, respectively obtained from ground motion prediction equations and non-linear Shallow-Water equations. The intensity measures inherent to each of the inextricable candidate sources, Scandidate, were characterized over 864 seismic and 144 tsunami simulations and then compared to key-thresholds to identify the scenarios with damaging potential, Seligible. The quantities of each Seligible were assessed varying the earthquake and tsunami intensity measures as leading measures to define a set of combined worst-case scenarios for the infrastructure, Sworst. The cascading loading patterns for structural design purposes are then derived following the European and North American code provisions for earthquake and tsunami actions, respectively. The prediction of the cascading loading pattern at the terminal container of the Sines port quantifies PGA around 0.37 g for a seismic displacement-controlled behavior and peaks of hydrostatic and hydrodynamic components values around 1000 kNm⁻¹ for tsunami force-controlled behavior during both the inflow and outflow cycles. A brief correlation between indicative action values and structural resistance of the current constructive solution raises awareness for the high probability of structural collapse of the pile-supported wharf due to an extreme 1755-alike Great Lisbon Earthquake and Tsunami threat, which would disrupt the port's operations and compromise its role as lifeline structure in case of emergency.
Recently, the North American and Japanese authorities began combining the tsunami forces with oth... more Recently, 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.
Numerical modelling is a fundamental tool for scenario-based evaluation of hazardous phenomena su... more Numerical modelling is a fundamental tool for scenario-based evaluation of hazardous phenomena such as tsunami. Nevertheless, the numerical prediction highly depends on the tool quality and therefore the design of efficient numerical schemes that provide robust and accurate solutions still receives considerable attention. In this paper, we implement two different second-order finite volume numerical schemes deriving from an a priori or an a posteri-ori limitation procedure and we compare their efficiency in solving the non-conservative shallow-water equations. The numerical schemes assessed here are two variants of the a priori Monotonic Upstream-Centred Scheme for Conservation Laws (MUSCL) and the recent a posteriori multidimensional optimal order detection (MOOD) technique. We benchmark the numerical code, equipped with MUSCL and MOOD techniques, against: (1) a 1-D stationary problem with non-constant bathymetry to assess the second-order convergence of the method when a smooth analytical solution is involved; (2) a 1-D dam-break test to show its capacity to deal with irregular and discontinuous bathymetry in wet zones; and (3) using a simple 1-D analytical tsunami benchmark, 'single wave on a sloping beach', we show that the classical 1-D shallow-water system can be accurately solved by the second-order finite volume methods. Furthermore, we test the performance of the numerical code for the real-case tsunami of Tohoku-Oki, 2011. Through a set of 2-D numerical simulations, the 2011 tsunami records from both DART and GPS buoys are checked against the simulated results using MUSCL and MOOD. We find that the use of the MOOD technique leads to a better approximation between the numerical solutions and the observations than the MUSCL one. MOOD allows sharper shock capture and generates less numerical diffusion, suggesting it as a promising technique for solving shallow-water problems.
Journal of Advances in Modeling Earth Systems, 2016
Tsunami modeling commonly accepts the shallow-water system as governing equations where the major... more Tsunami modeling commonly accepts the shallow-water system as governing equations where the major difficulty is the correct treatment of the non-conservative term due to bathymetry variations. The finite volume method for solving the shallow-water equations with such source terms has received great attention in the two last decades. The built-in conservation property, the capacity to correctly treat discontinuities, and the ability to handle complex bathymetry configurations preserving some steady-state configurations (well-balanced scheme) make the method very efficient. Nevertheless, it is still a challenge to build an efficient numerical scheme, with very few numerical artifacts (e.g. small numerical diffusion, correct propagation of the discontinuities, accuracy and robustness), to be used in an operational environment, and that is able to better capture the dynamics of the wet-dry interface and the physical phenomena that occur in the inundation area. In the first part of this paper, we present a new second-order finite volume code. The code is developed for the shallow-water equations with a non-conservative term based on the hydrostatic reconstruction technology to achieve a well-balanced scheme and an adequate dry/wet interface treatment. A detailed presentation of the numerical method is given. In the second part of the paper, we highlight the advantages of the new numerical technique. We benchmark the numerical code against analytical, experimental and field results to assess the robustness and the accuracy of the numerical code. Finally, we use the 28 February 1969 North East Atlantic tsunami to check the performance of the code with real data. This article is protected by copyright. All rights reserved.
On 8 May 1939, an earthquake (Ms7.1) occurred near the Azores archipelago, with an epicentre loca... more On 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.
Strong ground motion prediction based on finite-fault simulation requires the identification of t... more Strong ground motion prediction based on finite-fault simulation requires the identification of the fault (strike, dip, length and width), source kinematics parameters (stress drop, rupture velocity and slip distribution), regional crustal properties (geometrical spreading, anelastic structure, and upper crustal amplification and attenuation parameters) and the determination of amplification effects due to the local site geology. The general purpose of this study is to understand source and attenuation properties in the Azores, by the determination of stress drop, quality factor and kappa, through records obtained by the Portuguese digital seismic and accelerometer network. Source Spectra were obtained, for each record, after correcting observed spectra from geometrical spreading and anelastic attenuation effect: quality factor was estimated based on coda decay in the time domain and the kappa parameter was estimated by fitting the high-frequency decay of the acceleration spectrum with a straight line in a log-linear scale. Mean stress drop value was obtained considering that ω-squared model for the source spectra prevails. Parameters kappa, k, and quality factor, Q, have been estimated to be k = (0.075 ± 0.02)s and (Q(f) = (76 ± 11)f^(0.69 ± 0.09), respectively. A mean value of stress drop was estimated to be around 90–130 bars for the earthquakes in analysis. The knowledge of source and path parameters, in association with other ground motion parameters, allows improving ground-motion estimates for the Azores and, consequently, will lead to more accurate seismic hazard assessment for the Azores and better characterization of seismic scenarios.
Reis, C., Barbosa, A. R., Figueiredo, J., Clain, S., Lopes, M, & Baptista, M. A.. (2022). Smoothe... more Reis, C., Barbosa, A. R., Figueiredo, J., Clain, S., Lopes, M, & Baptista, M. A.. (2022). Smoothed particle hydrodynamics modeling of elevated structure impacted by tsunami-like waves. Engineering Structures, 270, 114851. DOI:10.1016/j.engstruct.2022.114851
International Journal of Disaster Risk Reduction , 2022
Preventive management strategies are evolving towards multi-hazard risk estimates. Commonly, the ... more Preventive management strategies are evolving towards multi-hazard risk estimates. Commonly, the multi-hazard characterization is pursued following a probabilistic approach. However, scenario-based evaluations can provide complementary key insights of relevance to design critical facilities. In this paper, an alternative deterministic analysis was explored to characterize the cascade seismic and tsunami actions of a 1755-alike Great Lisbon Earthquake and Tsunami event oriented to the container terminal of Sines deep-water seaport, Portugal, which is in expansion to increase the current 2.3 million TEU capacity to 7.1 million TEU. The analysis accounts source, propagation and site effects uncertainties influencing the multi-hazard estimates for different structural configurations representing the different stages of the extension plans for the infrastructure. The target-hazard assessment assumes ground motion acceleration and tsunami hydrostatic and hydrodynamic quantities as explanatory variables, respectively obtained from ground motion prediction equations and non-linear Shallow-Water equations. The intensity measures inherent to each of the inextricable candidate sources, Scandidate, were characterized over 864 seismic and 144 tsunami simulations and then compared to key-thresholds to identify the scenarios with damaging potential, Seligible. The quantities of each Seligible were assessed varying the earthquake and tsunami intensity measures as leading measures to define a set of combined worst-case scenarios for the infrastructure, Sworst. The cascading loading patterns for structural design purposes are then derived following the European and North American code provisions for earthquake and tsunami actions, respectively. The prediction of the cascading loading pattern at the terminal container of the Sines port quantifies PGA around 0.37 g for a seismic displacement-controlled behavior and peaks of hydrostatic and hydrodynamic components values around 1000 kNm⁻¹ for tsunami force-controlled behavior during both the inflow and outflow cycles. A brief correlation between indicative action values and structural resistance of the current constructive solution raises awareness for the high probability of structural collapse of the pile-supported wharf due to an extreme 1755-alike Great Lisbon Earthquake and Tsunami threat, which would disrupt the port's operations and compromise its role as lifeline structure in case of emergency.
Recently, the North American and Japanese authorities began combining the tsunami forces with oth... more Recently, 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.
Numerical modelling is a fundamental tool for scenario-based evaluation of hazardous phenomena su... more Numerical modelling is a fundamental tool for scenario-based evaluation of hazardous phenomena such as tsunami. Nevertheless, the numerical prediction highly depends on the tool quality and therefore the design of efficient numerical schemes that provide robust and accurate solutions still receives considerable attention. In this paper, we implement two different second-order finite volume numerical schemes deriving from an a priori or an a posteri-ori limitation procedure and we compare their efficiency in solving the non-conservative shallow-water equations. The numerical schemes assessed here are two variants of the a priori Monotonic Upstream-Centred Scheme for Conservation Laws (MUSCL) and the recent a posteriori multidimensional optimal order detection (MOOD) technique. We benchmark the numerical code, equipped with MUSCL and MOOD techniques, against: (1) a 1-D stationary problem with non-constant bathymetry to assess the second-order convergence of the method when a smooth analytical solution is involved; (2) a 1-D dam-break test to show its capacity to deal with irregular and discontinuous bathymetry in wet zones; and (3) using a simple 1-D analytical tsunami benchmark, 'single wave on a sloping beach', we show that the classical 1-D shallow-water system can be accurately solved by the second-order finite volume methods. Furthermore, we test the performance of the numerical code for the real-case tsunami of Tohoku-Oki, 2011. Through a set of 2-D numerical simulations, the 2011 tsunami records from both DART and GPS buoys are checked against the simulated results using MUSCL and MOOD. We find that the use of the MOOD technique leads to a better approximation between the numerical solutions and the observations than the MUSCL one. MOOD allows sharper shock capture and generates less numerical diffusion, suggesting it as a promising technique for solving shallow-water problems.
Journal of Advances in Modeling Earth Systems, 2016
Tsunami modeling commonly accepts the shallow-water system as governing equations where the major... more Tsunami modeling commonly accepts the shallow-water system as governing equations where the major difficulty is the correct treatment of the non-conservative term due to bathymetry variations. The finite volume method for solving the shallow-water equations with such source terms has received great attention in the two last decades. The built-in conservation property, the capacity to correctly treat discontinuities, and the ability to handle complex bathymetry configurations preserving some steady-state configurations (well-balanced scheme) make the method very efficient. Nevertheless, it is still a challenge to build an efficient numerical scheme, with very few numerical artifacts (e.g. small numerical diffusion, correct propagation of the discontinuities, accuracy and robustness), to be used in an operational environment, and that is able to better capture the dynamics of the wet-dry interface and the physical phenomena that occur in the inundation area. In the first part of this paper, we present a new second-order finite volume code. The code is developed for the shallow-water equations with a non-conservative term based on the hydrostatic reconstruction technology to achieve a well-balanced scheme and an adequate dry/wet interface treatment. A detailed presentation of the numerical method is given. In the second part of the paper, we highlight the advantages of the new numerical technique. We benchmark the numerical code against analytical, experimental and field results to assess the robustness and the accuracy of the numerical code. Finally, we use the 28 February 1969 North East Atlantic tsunami to check the performance of the code with real data. This article is protected by copyright. All rights reserved.
On 8 May 1939, an earthquake (Ms7.1) occurred near the Azores archipelago, with an epicentre loca... more On 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.
Strong ground motion prediction based on finite-fault simulation requires the identification of t... more Strong ground motion prediction based on finite-fault simulation requires the identification of the fault (strike, dip, length and width), source kinematics parameters (stress drop, rupture velocity and slip distribution), regional crustal properties (geometrical spreading, anelastic structure, and upper crustal amplification and attenuation parameters) and the determination of amplification effects due to the local site geology. The general purpose of this study is to understand source and attenuation properties in the Azores, by the determination of stress drop, quality factor and kappa, through records obtained by the Portuguese digital seismic and accelerometer network. Source Spectra were obtained, for each record, after correcting observed spectra from geometrical spreading and anelastic attenuation effect: quality factor was estimated based on coda decay in the time domain and the kappa parameter was estimated by fitting the high-frequency decay of the acceleration spectrum with a straight line in a log-linear scale. Mean stress drop value was obtained considering that ω-squared model for the source spectra prevails. Parameters kappa, k, and quality factor, Q, have been estimated to be k = (0.075 ± 0.02)s and (Q(f) = (76 ± 11)f^(0.69 ± 0.09), respectively. A mean value of stress drop was estimated to be around 90–130 bars for the earthquakes in analysis. The knowledge of source and path parameters, in association with other ground motion parameters, allows improving ground-motion estimates for the Azores and, consequently, will lead to more accurate seismic hazard assessment for the Azores and better characterization of seismic scenarios.
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Papers by Claudia Reis