A parametric study of thermomechanical 3D nite element simulations of subduction zones and its application to the Central Andes using realistic geometries

A parametric study of thermomechanical 3D nite element simulations of subduction zones and its application to the Central Andes using realistic geometries
Author: Chris Salomon
Publisher:
Total Pages:
Release: 2020*
Genre: Subduction zones
ISBN:

The western margin of central South America is one of the best studied regions of subduction zones. The oceanic Nazca plate descends beneath the continental South American plate at an oceanward concave trench. This form of the trench is unique on Earth and lead to the formation of the Andes. Here, I focus on a three-dimensional thermomechanical finite element model along the north Chilean margin. At first a reference model with simplified geometry reaching down to 400 km depth is created that makes use of an elasto-viscoplastic rheology including shear heating along the plate interface. The subduction process is simulated for geologically short timescales to reflect the recent state of subduction and the model results are in first-order agreement with observations. The model is analyzed within the framework of a parametric study revealing the most important parameters to be convergence and slab pull velocity, type and number of elements of the finite element mesh, type of rheology, cohesion, friction coefficient and angle of internal friction. Because of its lower thickness the oceanic crust is generally more affected by changes in these parameters than the continental crust. The final model includes a realistic geometry and density distribution that is based on a well constrained density model, not considering topography and bathymetry. It simulates 100,000 years of subduction and accounts for elastic deformations. The geometry has a major impact on the model results causing significant differences between the northern and southern parts of the model. This, as well as the final distributions of shear stress, strain rate and heat flux is in good agreement with observations from global models except for the magmatic arc because inelastic deformations are neglected. The usage of a realistic geometry and density distribution for finite element simulations of subduction zones can thus help to significantly improve future geodynamic models.

A parametric study of thermomechanical 3D nite element simulations of subduction zones and its application to the Central Andes using realistic geometries

A parametric study of thermomechanical 3D nite element simulations of subduction zones and its application to the Central Andes using realistic geometries
Author: Chris Salomon
Publisher:
Total Pages:
Release: 2020*
Genre:
ISBN:

The western margin of central South America is one of the best studied regions of subduction zones. The oceanic Nazca plate descends beneath the continental South American plate at an oceanward concave trench. This form of the trench is unique on Earth and lead to the formation of the Andes. Here, I focus on a three-dimensional thermomechanical finite element model along the north Chilean margin. At first a reference model with simplified geometry reaching down to 400 km depth is created that makes use of an elasto-viscoplastic rheology including shear heating along the plate interface. The subduction process is simulated for geologically short timescales to reflect the recent state of subduction and the model results are in first-order agreement with observations. The model is analyzed within the framework of a parametric study revealing the most important parameters to be convergence and slab pull velocity, type and number of elements of the finite element mesh, type of rheology, cohesion, friction coefficient and angle of internal friction. Because of its lower thickness the oceanic crust is generally more affected by changes in these parameters than the continental crust. The final model includes a realistic geometry and density distribution that is based on a well constrained density model, not considering topography and bathymetry. It simulates 100,000 years of subduction and accounts for elastic deformations. The geometry has a major impact on the model results causing significant differences between the northern and southern parts of the model. This, as well as the final distributions of shear stress, strain rate and heat flux is in good agreement with observations from global models except for the magmatic arc because inelastic deformations are neglected. The usage of a realistic geometry and density distribution for finite element simulations of subduction zones can thus help to significantly improve future geodynamic models.

Subduction

Subduction
Author: Alexander I. Shemenda
Publisher: Springer Science & Business Media
Total Pages: 242
Release: 1994-09-30
Genre: Science
ISBN: 9780792330424

This book is devoted to the quantitative physical modeling of subduction and subduction-related processes. It presents a coherent description of the modeling method (including similarity criteria, and a novel applied experimental technique), results from model experiments, theoretical analysis of results on the basis of continuum mechanics, and their geodynamic interpretation. Subduction is modeled in general as well as applied to particular regions using both 2-D and 3-D approaches, with both slab-push and slab-pull driving forces. The modeling covers all stages from subduction initiation to `death', different regimes of subduction producing back arc extension and compression, blocking of subduction and jumps of subduction zone, arc-continent collision and continental subduction. This work is for geologists and geophysicists interested in geodynamics of the convergent plate boundaries and in mechanics of the lithosphere.

An Introduction to Seismology, Earthquakes, and Earth Structure

An Introduction to Seismology, Earthquakes, and Earth Structure
Author: Seth Stein
Publisher: John Wiley & Sons
Total Pages: 512
Release: 2013-05-30
Genre: Science
ISBN: 1118687450

An Introduction to Seismology, Earthquakes and Earth Structures is an introduction to seismology and its role in the earth sciences, and is written for advanced undergraduate and beginning graduate students. The fundamentals of seismic wave propagation are developed using a physical approach and then applied to show how refraction, reflection, and teleseismic techniques are used to study the structure and thus the composition and evolution of the earth. The book shows how seismic waves are used to study earthquakes and are integrated with other data to investigate the plate tectonic processes that cause earthquakes. Figures, examples, problems, and computer exercises teach students about seismology in a creative and intuitive manner. Necessary mathematical tools including vector and tensor analysis, matrix algebra, Fourier analysis, statistics of errors, signal processing, and data inversion are introduced with many relevant examples. The text also addresses the fundamentals of seismometry and applications of seismology to societal issues. Special attention is paid to help students visualize connections between different topics and view seismology as an integrated science. An Introduction to Seismology, Earthquakes, and Earth Structure gives an excellent overview for students of geophysics and tectonics, and provides a strong foundation for further studies in seismology. Multidisciplinary examples throughout the text - catering to students in varied disciplines (geology, mineralogy, petrology, physics, etc.). Most up to date book on the market - includes recent seismic events such as the 1999 Earthquakes in Turkey, Greece, and Taiwan). Chapter outlines - each chapter begins with an outline and a list of learning objectives to help students focus and study. Essential math review - an entire section reviews the essential math needed to understand seismology. This can be covered in class or left to students to review as needed. End of chapter problem sets - homework problems that cover the material presented in the chapter. Solutions to all odd numbered problem sets are listed in the back so that students can track their progress. Extensive References - classic references and more current references are listed at the end of each chapter. A set of instructor's resources containing downloadable versions of all the figures in the book, errata and answers to homework problems is available at: http://levee.wustl.edu/seismology/book/. Also available on this website are PowerPoint lecture slides corresponding to the first 5 chapters of the book.

The Andes

The Andes
Author: Onno Oncken
Publisher: Springer Science & Business Media
Total Pages: 574
Release: 2006-11-22
Genre: Science
ISBN: 3540486844

This book provides the first comprehensive overview of a complete subduction orogen, the Andes. To date the results provide the densest and most highly resolved geophysical image of an active subduction orogen.

Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space

Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space
Author: National Academies of Sciences, Engineering, and Medicine
Publisher: National Academies Press
Total Pages: 29
Release: 2019-06-18
Genre: Science
ISBN: 0309492432

We live on a dynamic Earth shaped by both natural processes and the impacts of humans on their environment. It is in our collective interest to observe and understand our planet, and to predict future behavior to the extent possible, in order to effectively manage resources, successfully respond to threats from natural and human-induced environmental change, and capitalize on the opportunities â€" social, economic, security, and more â€" that such knowledge can bring. By continuously monitoring and exploring Earth, developing a deep understanding of its evolving behavior, and characterizing the processes that shape and reshape the environment in which we live, we not only advance knowledge and basic discovery about our planet, but we further develop the foundation upon which benefits to society are built. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space (National Academies Press, 2018) provides detailed guidance on how relevant federal agencies can ensure that the United States receives the maximum benefit from its investments in Earth observations from space, while operating within realistic cost constraints. This short booklet, designed to be accessible to the general public, provides a summary of the key ideas and recommendations from the full decadal survey report.

Advanced Geodynamics

Advanced Geodynamics
Author: David T. Sandwell
Publisher: Cambridge University Press
Total Pages: 283
Release: 2022-01-27
Genre: Science
ISBN: 1009021494

David Sandwell developed this advanced textbook over a period of nearly 30 years for his graduate course at Scripps Institution of Oceanography. The book augments the classic textbook Geodynamics by Don Turcotte and Jerry Schubert, presenting more complex and foundational mathematical methods and approaches to geodynamics. The main new tool developed in the book is the multi-dimensional Fourier transform for solving linear partial differential equations. The book comprises nineteen chapters, including: the latest global data sets; quantitative plate tectonics; plate driving forces associated with lithospheric heat transfer and subduction; the physics of the earthquake cycle; postglacial rebound; and six chapters on gravity field development and interpretation. Each chapter has a set of student exercises that make use of the higher-level mathematical and numerical methods developed in the book. Solutions to the exercises are available online for course instructors, on request.