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Erosion and Earthquakes – EROQUAKE

Erosion and Earthquakes

Understanding how tectonics, climate and surface processes interact to shape the Earth’s surface is one of the most challenging issues in Earth sciences. Numerous studies have addressed this question considering mountain belt evolution without properly accounting for the short time-scale (< 1000 yr) physics of tectonics and surface processes. Our ambition is therefore to address the issue of the feedbacks between tectonics and surface processes at the time-scale of a seismic cycle.

Our objectives are to model the impact of earthquakes on landscape evolution and to demonstrate how surface processes can influence fault seismicity.

The idea of our project is motivated by the recent findings showing 1) that the net topographic effect of large earthquakes (magnitude > 7) can be negative, i.e. that the erosion induced by these earthquakes can be greater than the co-seismic uplift; and 2) that surface processes, including erosion and sedimentation, can increase the stress loading of active faults and trigger shallow seismicity. To go beyond these findings, we wish to investigate three main questions :<br />1) How landscapes and surface processes (landslides, river erosion, transport and avulsion) respond to large earthquakes. <br />2) How surface processes during the co-, post- and inter-seismic periods influence stress loading, seismicity, and displacements of active fault planes. <br />3) How the interactions between surface processes and tectonics during the seismic cycle influence mountain building.<br /><br />This basic research project has three tasks but a single problematic, which is to understand the feedbacks and interactions between surface processes and crustal deformation during the seismic cycle of active mountain belts.<br />

We use the €ROS numerical model, which is the only landscape evolution model to our knowledge able to investigate the dynamics of landscapes and surface processes (landslides, extreme sediment transport, river narrowing/widening, river avulsion) during the co- and post-seismic phases of a large earthquake. To model the impact of erosion on seismicity and deformation during the seismic cycle, we use the Bicycle elasto-dynamic model. At the time-scale of a seismic-cycle, no attempt has yet been made to couple “solid earth” models to models of landscape evolution. We therefore continue the development of a 3D visco-elastic numerical model for the lithosphere that account for the influence of surface processes and of faults and shear zones by the means of Okada-type dislocations. We apply our models to Taiwan and the Southern Alps of New-Zealand, which are well-documented mountain belts displaying very high rates of erosion and tectonic activity.

In progress

In progress

Steer, P., Simoes, M., Cattin, R., & Shyu, J. B. H. (2014). Erosion influences the seismicity of active thrust faults. Nature communications, 5.

Understanding how tectonics, climate and surface processes interact to shape the Earth’s surface is one of the most challenging issues in earth sciences. Over the last few decades, numerous studies have addressed this question considering landscapes and mountain belt evolution on geological time-scales (1 - 100 Myr) without properly accounting for the short time-scale (< 1000 yr) physics of tectonics and surface processes and their feedbacks. Indeed, our preliminary work shows 1) that the net topographic effect of large earthquakes (magnitude > 7) can be negative, i.e. that the erosion induced by these earthquakes can be greater than the co-seismic uplift; and 2) that surface processes, including erosion and sedimentation, can increase the stress loading of active faults and trigger shallow seismicity. Our ambition with this project is therefore to address, for the first time, the issue of the feedbacks and interactions between tectonics and surface processes at the time-scale of a seismic cycle (<1000 yr).

We will combine numerical models with field data to investigate:
TASK 4) How landscapes and surface processes (landslides, river erosion, transport and avulsion) respond to large earthquakes.
TASK 5) How surface processes during the co-, post- and inter-seismic periods influence stress loading, seismicity, and displacements of active fault planes.
TASK 6) How the interactions between surface processes and tectonics during the seismic cycle influence mountain building.

This basic research project has three tasks but a single problematic, which is to understand the feedbacks and interactions between surface processes and crustal deformation during the seismic cycle of active mountain belts. We will use the €ROS numerical model, which is the only landscape evolution model to our knowledge able to investigate the dynamics of landscapes and surface processes (landslides, extreme sediment transport, river narrowing/widening, river avulsion) during the co- and post-seismic phases of a large earthquake. At the time-scale of a seismic-cycle, no attempt has yet been made to couple “solid earth” models to models of landscape evolution. We will therefore continue the development of a 3D visco-elastic numerical model for the lithosphere that will account for the influence of surface processes and of faults and shear zones by the means of Okada-type dislocations. We will apply our models to Taiwan and the Southern Alps of New-Zealand, which are well-documented mountain belts displaying very high rates of erosion and tectonic activity. This project will benefit from the competences on the modeling of surface processes of our Quantitative Geomorphology team at Géosciences Rennes (Université Rennes 1) and the ones of our external collaborators on tectonics during the seismic cycle and on landscape evolution during and after large earthquakes. By offering new insights on the relationship between extreme climatic, erosional and tectonics events, the results of our project will have direct and strong societal implications, in particular concerning natural hazard assessment.

Project coordination

Philippe Steer (Géosciences Rennes UMR 6118)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

GEOSCIENCES Géosciences Rennes UMR 6118

Help of the ANR 196,576 euros
Beginning and duration of the scientific project: September 2014 - 48 Months

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