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Genesis of mega-thrust earthquakes at convergent plate boundaries: modelling of seismic coupling combining geodynamic and earthquake-faulting models

English title Genesis of mega-thrust earthquakes at convergent plate boundaries: modelling of seismic coupling combining geodynamic and earthquake-faulting models
Applicant Dalguer Luis
Number 144398
Funding scheme Project funding
Research institution Institut für Geophysik ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Geophysics
Start/End 01.10.2012 - 31.05.2013
Approved amount 44'218.00
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Keywords (6)

mega-thrust earthquakes; dynamic rupture modeling; numerical modeling of geodynamic processes; earthquake source physics; geodynamics of subduction zones; seismic cycles

Lay Summary (English)

Lead
Lay summary

This project is an extension of the (SNSF) funded project 200021-125274/4 to support one PhD researcher (Ylona van Dinther). The objective is to develop a new interdisciplinary, integrative approach for numerically modeling geodynamic and earthquake rupture processes to investigate the seismic cycle at subduction zones.

The original project consisted of six tasks that we re-allocated into four broader, composite tasks. In Task 1 (completed) we demonstrate that a continuum-mechanics based, visco-elasto-plastic approach, typically used for large-scale geodynamic problems, can be extended to study the relatively shorter-term seismic cycle (van Dinther et al, 2012a, submitted). This major breakthrough was accomplished by a benchmark with laboratory models, which is described in Corbi et al. (2012, submitted) in which the PhD candidate is co-author. The source parameter comparison demonstrated the necessity of a new implementation of a slip velocity-dependent frictional formulation. Using this new approach, we find that simulated GPS displacements reveal the possibility of measuring the inter-, co- and postseismic deformation, providing unique insights for earthquake forecasting. In addition, we observed several dynamic rupture features that are currently intensely debated in the rupture dynamics community, including pulses, cracks, and fault re-rupturing.

Task 2 builds on Task 1 to investigate the seismic cycle in a more realistic geometry for complex continental margins. This leading-edge approach, which is currently fine-tuned, is the first of its kind that contains the three key ingredients to simulate the seismic cycle: a rate-dependent friction, slow tectonic loading, and visco-elastic mantle relaxation. The innovative character of our approach opens rarely explored possibilities to investigate the spatio-temporal relation between different seismicity clusters, surface displacements relating to afterslip and mantle relaxation, and slow-slip phenomena.

We recently initiated Task 3, in which we couple our upgraded geodynamic code to a dynamic rupture simulation method. Task 4 applied our geodynamic approach to the M9.2 Sumatra event. This collaboration, finalized from our side, demonstrated the necessity of both mantle relaxation and aseismic afterslip to match gravity observations.

This continuation proposal, aims to finalize this highly innovative and interdisciplinary scientific research, which has gained momentum after we developed a new methodology that generates and quantifies seismic events in geodynamic models. The project progressed from the development to the benchmarking stage, overcoming a number of computational and scientific challenges, and has now entered the production stage. By finalizing the initiated Tasks 2 and 3, we expect at least two additional high level first-author publications on the generation and characteristics of mega-thrust earthquakes in subduction zones.


Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
The seismic cycle at subduction thrusts: 2. Dynamic implications of geodynamic simulations bench- marked with laboratory models
van Dinther Ylona (2013), The seismic cycle at subduction thrusts: 2. Dynamic implications of geodynamic simulations bench- marked with laboratory models, in Journal of Geophysical Research - Solid Earth, 1502.

Collaboration

Group / person Country
Types of collaboration
Prof. Gabriele Morra, School of Earth and Environmental Sciences, Seoul National University Korean Republic (South Korea) (Asia)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Prof. Taras Gerya, Institute of Geophysics, ETH-Zurich Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Prof. Giardini, Institute of Geophysics, ETH-Zurich Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Dr. F. Funicello, Department of Geology, Universita degli studi 'Roma Tre' Italy (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Prof. Martin Mai, King Abdullah University for Science and Techonology (KAUST) Saudi Arabia (Asia)
- in-depth/constructive exchanges on approaches, methods or results
- Publication

Associated projects

Number Title Start Funding scheme
125274 Genesis of mega-thrust earthquakes events at convergent plate boundaries: 3D modelling of seismic coupling combining geodynamic and earthquake-faulting models 01.06.2009 Project funding

Abstract

In 2009, the Swiss National Science Foundation (SNSF) funded project 200021-125274/4 to support one PhD researcher (Ylona van Dinther). The objective was to develop a new interdisciplinary, integrative approach for numerically modeling geodynamic and earthquake rupture processes to investigate the seismic cycle at subduction zones. The original project consisted of six tasks that we re-allocated into four broader, composite tasks. In Task 1 (completed) we demonstrate that a continuum-mechanics based, visco-elasto-plastic approach, typically used for large-scale geodynamic problems, can be extended to study the relatively shorter-term seismic cycle (van Dinther et al, 2012a, submitted). This major breakthrough was accomplished by a benchmark with laboratory models, which is described in Corbi et al. (2012, submitted) in which the PhD candidate is co-author. The source parameter comparison demonstrated the necessity of a new implementation of a slip velocity-dependent frictional formulation. Using this new approach, we find that simulated GPS displacements reveal the possibility of measuring the inter-, co- and postseismic deformation, providing unique insights for earthquake forecasting. In addition, we observed several dynamic rupture features that are currently intensely debated in the rupture dynamics community, including pulses, cracks, and fault re-rupturing. Task 2 builds on Task 1 to investigate the seismic cycle in a more realistic geometry for complex continental margins. This leading-edge approach, which is currently fine-tuned, is the first of its kind that contains the three key ingredients to simulate the seismic cycle: a rate-dependent friction, slow tectonic loading, and visco-elastic mantle relaxation. The innovative character of our approach opens rarely explored possibilities to investigate the spatio-temporal relation between different seismicity clusters, surface displacements relating to afterslip and mantle relaxation, and slow-slip phenomena. We recently initiated Task 3, in which we couple our upgraded geodynamic code to a dynamic rupture simulation method. This utilizes the strengths of both approaches: geodynamic models provide the much needed physics-based input on the preseismic stress state and geometrical complexities, whilst the dynamic rupture code solves for the geodynamically absent inertial dynamics and full fault coupling. Task 4 applied our geodynamic approach to the M9.2 Sumatra event. This collaboration, finalized from our side, demonstrated the necessity of both mantle relaxation and aseismic afterslip to match gravity observations. This continuation proposal, requesting 12 months of PhD salary, is submitted to finalize this highly innovative and interdisciplinary scientific research, which has gained momentum after we developed a new methodology that generates and quantifies seismic events in geodynamic models. The project progressed from the development to the benchmarking stage, overcoming a number of computational and scientific challenges, and has now entered the production stage. By finalizing the initiated Tasks 2 and 3, we expect at least two additional high level first-author publications on the generation and characteristics of mega-thrust earthquakes in subduction zones.
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