scholarly journals Analogue earthquakes and seismic cycles: Experimental modelling across timescales

2016 ◽  
Author(s):  
Matthias Rosenau ◽  
Fabio Corbi ◽  
Stephane Dominguez
Keyword(s):  
Numerical Models ◽  
Experimental Modelling ◽  
Rupture Dynamics ◽  
Scale Models ◽  
Analogue Models ◽  
Elastic Rebound ◽  
Earthquake Modelling ◽  
Earthquake Model ◽  
Mechanical Models ◽  
Long Timescales

Abstract. Since the formulation of Reid’s elastic rebound theory 100 years ago laboratory mechanical models combining frictional and elastic elements have joined the forefront of the research on the dynamics of earthquakes. In the last decade, with the advent of high resolution monitoring techniques and new rock analogue materials, laboratory earthquake experiments kept developing from simple spring-slider models to more sophisticated scaled analogue models. This evolution was accomplished by advances in seismology and geodesy which, along with a culmination of large earthquakes, have significantly increased the quality and quantity of relevant observations in nature. We here review the cornerstones of analogue earthquake model developments with a focus on scale models which are directly comparable to observational data on short to long timescales. We revisit the basics of analogue modelling, namely scaling, materials and monitoring, as applied in earthquake modelling. An overview of applications highlights the contributions of analogue earthquake models in bridging timescales of observations including earthquake statistics, rupture dynamics, ground motion and seismic cycle deformation up to seismotectonic evolution. We finally discuss limits, challenges and links to numerical models.

scholarly journals Analogue earthquakes and seismic cycles: experimental modelling across timescales

Solid Earth ◽  
2017 ◽  
Vol 8 (3) ◽  
pp. 597-635 ◽  
Author(s):  
Matthias Rosenau ◽  
Fabio Corbi ◽  
Stephane Dominguez
Keyword(s):  
Tectonic Deformation ◽  
Earthquake Dynamics ◽  
Experimental Modelling ◽  
Rupture Dynamics ◽  
Analogue Models ◽  
Elastic Rebound ◽  
Earthquake Modelling ◽  
Mechanical Models ◽  
Seismic Deformation ◽  
Long Timescales

Abstract. Earth deformation is a multi-scale process ranging from seconds (seismic deformation) to millions of years (tectonic deformation). Bridging short- and long-term deformation and developing seismotectonic models has been a challenge in experimental tectonics for more than a century. Since the formulation of Reid's elastic rebound theory 100 years ago, laboratory mechanical models combining frictional and elastic elements have been used to study the dynamics of earthquakes. In the last decade, with the advent of high-resolution monitoring techniques and new rock analogue materials, laboratory earthquake experiments have evolved from simple spring-slider models to scaled analogue models. This evolution was accomplished by advances in seismology and geodesy along with relatively frequent occurrences of large earthquakes in the past decade. This coincidence has significantly increased the quality and quantity of relevant observations in nature and triggered a new understanding of earthquake dynamics. We review here the developments in analogue earthquake modelling with a focus on those seismotectonic scale models that are directly comparable to observational data on short to long timescales. We lay out the basics of analogue modelling, namely scaling, materials and monitoring, as applied in seismotectonic modelling. An overview of applications highlights the contributions of analogue earthquake models in bridging timescales of observations including earthquake statistics, rupture dynamics, ground motion, and seismic-cycle deformation up to seismotectonic evolution.

scholarly journals Thermal Finite Element Modelling of the Laser Beam Welding of Tailor Welded Blanks through an Equivalent Volumetric Heat Source

2021 ◽  
Author(s):  
Vito Busto ◽  
Donato Coviello ◽  
Andrea Lombardi ◽  
Mariarosaria De Vito ◽  
Donato Sorgente
Keyword(s):  
Finite Element ◽  
Heat Source ◽  
Numerical Models ◽  
Laser Beam Welding ◽  
Welding Process ◽  
Butt Joint ◽  
Volumetric Heat Source ◽  
Tailor Welded Blanks ◽  
Mechanical Models ◽  
Physical Phenomena

Abstract In last decades, several numerical models of the keyhole laser welding process were developed in order to simulate the joining process. Most of them are sophisticated multiphase numerical models tempting to include all the several different physical phenomena involved. However, less computationally expensive thermo-mechanical models that are capable of satisfactorily simulating the process were developed as well. Among them, a moving volumetric equivalent heat source, whose dimensions are calibrated on experimental melt pool geometries, can estimate some aspects of the process using a Finite Element Method (FEM) modelling with no need to consider fluid flows. In this work, a double-conical volumetric heat source is used to arrange a combination of two half hourglass-like shapes with different dimensions each other. This particular arrangement aims to properly assess the laser joining of a Tailor Welded Blank (TWB) even in case of butt joint between sheets of different thicknesses. Experiments of TWBs made of 22MnB5 steel sheets were conducted in both equal and different thicknesses configurations in order to validate the proposed model. The results show that the model can estimate in a satisfactory way the shape and dimensions of the fused zone in case of TWB made of sheets with different thickness.

scholarly journals Rupture-dependent breakdown energy in fault models with thermo-hydro-mechanical processes

2020 ◽  
Author(s):  
Valère Lambert ◽  
Nadia Lapusta
Keyword(s):  
Material Property ◽  
Numerical Models ◽  
Slip Rate ◽  
Shear Cracks ◽  
Dynamic Rupture ◽  
Rupture Dynamics ◽  
Stress Changes ◽  
History Of ◽  
Thermal Pressurization ◽  
Pass Through

Abstract. Substantial insight into earthquake source processes has resulted from considering frictional ruptures analogous to cohesive-zone shear cracks from fracture mechanics. This analogy holds for slip-weakening representations of fault friction that encapsulate the resistance to rupture propagation in the form of breakdown energy, analogous to fracture energy, prescribed in advance as if it were a material property of the fault interface. Here, we use numerical models of earthquake sequences with enhanced weakening due to thermal pressurization of pore fluids to show how accounting for thermo-hydro-mechanical processes during dynamic shear ruptures makes breakdown energy rupture-dependent. We find that local breakdown energy is neither a constant material property nor uniquely defined by the amount of slip attained during rupture, but depends on how that slip is achieved through the history of slip rate and dynamic stress changes during the rupture process. As a consequence, the frictional breakdown energy of the same location along the fault can vary significantly in different earthquake ruptures that pass through. These results suggest the need for re-examining the assumption of pre-determined frictional breakdown energy common in dynamic rupture modeling and for better understanding of the factors that control rupture dynamics in the presence of thermo-hydro-mechanical processes.

scholarly journals Modeling Wear for Heterogeneous Bi-Phasic Materials Using Discrete Elements Approach

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Matthieu Champagne ◽  
Mathieu Renouf ◽  
Yves Berthier
Keyword(s):  
Friction And Wear ◽  
Numerical Models ◽  
Real Life ◽  
Limited Range ◽  
Friction Material ◽  
Contact Interface ◽  
Discrete Elements ◽  
Proper Understanding ◽  
Scale Models ◽  
Automotive Brake

A proper understanding of the processes of friction and wear can only be reached through a detailed study of the contact interface. Empirical laws, such as Archard's, are often used in numerical models. They give good results over a limited range of conditions when their coefficients are correctly set, but they cannot be predicted: any significant change of conditions requires a new set of experimental coefficients. In this paper, a new method, the use of discrete element models (DEMs), is proposed in order to tend to predictable models. As an example, a generic biphasic friction material is modeled, of the type used in aeronautical or automotive brake systems. Micro-scale models are built in order to study material damage and wear under tribological stress. The models show what could be achieved by these numerical methods in tribological studies and how they can reproduce the behavior and mechanisms seen with real-life friction materials without any empirical law or parameter.

A Spectral Boundary-Integral Method for Quasi-Dynamic Ruptures of Multiple Parallel Faults

2021 ◽  
Author(s):  
Sylvain Barbot
Keyword(s):  
Integral Method ◽  
Numerical Models ◽  
Boundary Integral ◽  
Boundary Integral Method ◽  
Three Dimensions ◽  
Power Law Distribution ◽  
Slow Slip Events ◽  
Multiple Faults ◽  
Rupture Dynamics ◽  
Wide Range

ABSTRACT Numerical models of rupture dynamics provide great insights into the physics of fault failure. However, resolving stress interactions among multiple faults remains challenging numerically. Here, we derive the elastostatic Green’s functions for stress and displacement caused by arbitrary slip distributions along multiple parallel faults. The equations are derived in the Fourier domain, providing an efficient means to calculate stress interactions with the fast Fourier transform. We demonstrate the relevance of the method for a wide range of applications, by simulating the rupture dynamics of single and multiple parallel faults controlled by a rate- and state-dependent frictional contact, using the spectral boundary integral method and the radiation-damping approximation. Within the antiplane strain approximation, we show seismic cycle simulations with a power-law distribution of rupture sizes and, in a different parameter regime, sequences of seismogenic slow-slip events. Using the in-plane strain approximation, we simulate the rupture dynamics of a restraining stepover. Finally, we describe cycles of large earthquakes along several parallel strike-slip faults in three dimensions. The approach is useful to explore the dynamics of interacting or isolated faults with many degrees of freedom.

Free slip conditions in 3D, what does it actually mean ?

2020 ◽  
Author(s):  
Laetitia Le Pourhiet ◽  
Anthony Jourdon ◽  
Louise Watremez ◽  
Bruno Vendeville
Keyword(s):  
Boundary Conditions ◽  
Numerical Simulations ◽  
Numerical Models ◽  
Boundary Effects ◽  
Tectonic Structures ◽  
Analogue Model ◽  
Slip Boundary ◽  
Analogue Models ◽  
Long Time ◽  
Quantum Technology

<p>For long time,3D tectonic modelling was reserved to analog methods and many practitioners spent a lot of time and energy developing methods and materials to make their naturally 3D "simulations" as cylindrical as possible.</p><p>Fighting with so-called boundary effects, they actually obtained a lot of interesting structures and dynamics related to "border effects" . In the last 5 years, 3D numerical simulations have really emerged thanks to new numerical technics and increase in available 'computational power. The two methods are now competing and sooner or later, with the emergence of exa-scale and quantum technology, it is quite certain that numerical simulations will dominate the field because it is much better suited to tackle multi- physics problems arising in long term tectonics.</p><p>However, before entering an era of mass production, it is interesting to re-think how we introduce 3 dimensionality in numerical models. Numerical models can easily produce perfectly free slip boundary conditions, and it has therefore never been a problem to simulate a perfectly cylindrical situation. Is it useful ? Not really since we can run 2D simulations.</p><p>However, many models introduce the 3 dimensionality by imposing inherited structures in simulations that use perfectly cylindrical boundary conditions. Technically this corresponds to imposing free slip boundaries in the third dimensions. Nobody question it, and in a way, we numerical modellers, are just mimicking traditional analogue model set ups and emphazing on the multi-physics aspect of our simulations.</p><p>Yet, comparing to analogue models, we some time reach different solutions and sometimes, analogue models with their boundary effects produce tectonic structures that are much more realistic than models with perfectly free slip boundaries.</p><p>In this pico presentation, I will show exemples of free slip boundaries that introduce biased in continental break-up propagation models and discuss in which conditions free slips are acceptable and in which conditions are should be carefull in our interpretations of simulation results.</p>

Development of C- shear bands in brittle-ductile shear zones: Insights from analogue and numerical models.

2020 ◽  
Author(s):  
Arnab Roy ◽  
Nandan Roy ◽  
Puspendu Saha ◽  
Nibir Mandal
Keyword(s):  
Shear Zone ◽  
Numerical Models ◽  
Shear Bands ◽  
Shear Zones ◽  
Rheological Parameters ◽  
Comprehensive Understanding ◽  
Experimental Conditions ◽  
Ductile Shear Zones ◽  
Analogue Models ◽  
Ductile Shear

<p>Development of brittle and brittle-ductile shear zones involve partitioning of large shear strains in bands, called C-shear bands (C-SB) nearly parallel to the shear zone boundaries. Our present work aims to provide a comprehensive understanding of the rheological factors in controlling such SB growth in meter scale natural brittle- ductile shear zones observed in in Singbhum and Chotonagpur mobile belts.  The shear zones show C- SB at an angle of 0°- 5° with the shear zone boundary. We used analogue models, based on Coulomb and Viscoplastic rheology to reproduce them in experimental conditions.</p><p>These models produce dominantly Riedel (R) shear bands. We show a transition from R-shearing in conjugate to single sets at angles of ~15<sup>o</sup> by changing model materials. However, none of the analogue models produced C-SB, as observed in the field. To reconcile the experimental and field findings, numeral models have been used to better constrain the geometrical and rheological parameters. We simulate model shear zones replicating those observed in the field, which display two distinct zones: drag zone where the viscous strains dominate  and the core zone, where both viscous and plastic strains come into play.  Numerical model results suggest the formation of  C- SB for a specific rheological condition. We also show varying shear band patterns as a function of the thickness ratio between drag and core zones.</p>

The 2018 version of the Global Earthquake Model: Hazard component

2020 ◽  
Vol 36 (1_suppl) ◽  
pp. 226-251 ◽  
Author(s):  
Marco Pagani ◽  
Julio Garcia-Pelaez ◽  
Robin Gee ◽  
Kendra Johnson ◽  
Valerio Poggi ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Regional Scale ◽  
Global Scale ◽  
Hazard Models ◽  
Probabilistic Seismic Hazard ◽  
Implementation Phase ◽  
Current State ◽  
Scale Models ◽  
Earthquake Model ◽  
National Models

In December 2018, at the conclusion of its second implementation phase, the Global Earthquake Model (GEM) Foundation released its first version of a map outlining the spatial distribution of seismic hazard at a global scale. The map is the result of an extensive, joint effort combining the results obtained from a collection of probabilistic seismic hazard models, called the GEM Mosaic. Together, the map and the underlying database of models provide an up-to-date view of the earthquake threat globally. In addition, using the Mosaic, a synopsis of the current state-of-practice in modeling probabilistic seismic hazard at national and regional scales is possible. The process adopted for the compilation of the Mosaic adhered to the maximum extent possible to GEM’s principles of collaboration, inclusiveness, transparency, and reproducibility. For each region, priority was given to seismic hazard models either developed by well-recognized national agencies or by large collaborative projects involving local scientists. The version of the GEM Mosaic presented herein contains 30 probabilistic seismic hazard models, 14 of which represent national or sub-national models; the remainder are regional-scale models. We discuss the general qualities of these models, the underlying framework of the database, and the outlook for the Mosaic’s utility and its future versions.

An Object-Oriented Analysis of Complex Numerical Models

2014 ◽  
Vol 611-612 ◽  
pp. 1356-1363 ◽  
Author(s):  
Piotr Macioł ◽  
Romain Bureau ◽  
Christof Sommitsch
Keyword(s):  
Numerical Models ◽  
Object Oriented ◽  
Scale Model ◽  
Internal Variables ◽  
Object Oriented Design ◽  
Multi Scale ◽  
Advantages And Disadvantages ◽  
Single Scale ◽  
Scale Models ◽  
Modelling Methodology

Modelling the behaviour of metal alloys during their thermo-mechanical processing relies on the physical and mathematical description of numerous phenomena occurring in several space scales and evolving on different characteristic times. Although it is possible to develop complicated multi-scale models, it is often simpler to simulate each phenomenon separately in a single-scale model and link all the models together in a global structure responsible for their good interaction. Such a structure is relatively difficult to design. Both efficiency and flexibility must be well balanced, keeping in mind the character of scientific computing. In that context, the Agile Multiscale Modelling Methodology (AM3) has been developed in order to support the object-oriented designing of complex numerical models [. In this paper, the application of the AM3 for designing a model of the metal alloy behaviour is presented. The basis and some consequences of the application of the Object-Oriented design of a sub-models structure are investigated. The object-oriented (OO) design of a 3 internal variables model of the dislocations evolution is presented and compared to the procedural one. The main advantages and disadvantages of the OO design of numerical models are pointed out.

scholarly journals Rupture-dependent breakdown energy in fault models with thermo-hydro-mechanical processes

Solid Earth ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 2283-2302
Author(s):  
Valère Lambert ◽  
Nadia Lapusta
Keyword(s):  
Material Property ◽  
Numerical Models ◽  
Slip Rate ◽  
Shear Cracks ◽  
Dynamic Rupture ◽  
Rupture Dynamics ◽  
Stress Changes ◽  
History Of ◽  
Thermal Pressurization ◽  
Pass Through

Abstract. Substantial insight into earthquake source processes has resulted from considering frictional ruptures analogous to cohesive-zone shear cracks from fracture mechanics. This analogy holds for slip-weakening representations of fault friction that encapsulate the resistance to rupture propagation in the form of breakdown energy, analogous to fracture energy, prescribed in advance as if it were a material property of the fault interface. Here, we use numerical models of earthquake sequences with enhanced weakening due to thermal pressurization of pore fluids to show how accounting for thermo-hydro-mechanical processes during dynamic shear ruptures makes breakdown energy rupture-dependent. We find that local breakdown energy is neither a constant material property nor uniquely defined by the amount of slip attained during rupture, but depends on how that slip is achieved through the history of slip rate and dynamic stress changes during the rupture process. As a consequence, the frictional breakdown energy of the same location along the fault can vary significantly in different earthquake ruptures that pass through. These results suggest the need to reexamine the assumption of predetermined frictional breakdown energy common in dynamic rupture modeling and to better understand the factors that control rupture dynamics in the presence of thermo-hydro-mechanical processes.

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