Related Experiment Video
Updated: Mar 11, 2026
12:30
High-pressure, High-temperature Deformation Experiment Using the New Generation Griggs-type Apparatus
Published on: April 3, 2018
19.6K
Mega-earthquakes rupture flat megathrusts
Quentin Bletery1, Amanda M Thomas2, Alan W Rempel2
1Department of Earth Sciences, University of Oregon, 1272 University of Oregon, Eugene, OR 97403, USA. qbletery@uoregon.edu.
Science (New York, N.Y.)
|November 26, 2016
Summary
Mega-earthquakes do not require fast convergence or young lithosphere. Instead, mega-earthquake rupture is linked to flat, low-curvature subduction zones, which promote homogeneous shear strength for widespread rupture.
Area of Science:
- Geophysics
- Seismology
- Tectonics
Background:
- The 2004 Sumatra-Andaman and 2011 Tohoku-Oki earthquakes revealed incomplete understanding of mega-earthquake dynamics.
- Previous assumptions linked mega-earthquakes to fast convergence and young, buoyant lithosphere, which is now challenged.
Purpose of the Study:
- To investigate the geometric factors controlling mega-earthquake rupture.
- To identify the relationship between subduction zone geometry and the occurrence of mega-earthquakes.
Main Methods:
- Calculation of interface curvature along global subduction zones.
- Development of a simplified analytic model to assess shear strength heterogeneity.
Main Results:
- Mega-earthquakes preferentially occur on flat (low-curvature) subduction interfaces.
- Interface curvature correlates with increased heterogeneity in shear strength.
- Flat megathrusts exhibit more homogeneous shear strength, facilitating simultaneous rupture over larger areas.
Conclusions:
- Subduction zone geometry, specifically interface curvature, is a critical factor in mega-earthquake rupture.
- Low-curvature interfaces promote the conditions necessary for large-area, simultaneous shear stress release characteristic of mega-earthquakes.
Related Concept Videos
01:24Stress-Strain Diagram - Brittle Materials
4.7K
Brittle materials, including glass, cast iron, and stone, exhibit unique characteristics. They fracture without considerable change in their elongation rate, indicating that their breaking and ultimate strength are equivalent. Such materials also show lower strain levels at the point of rupture. The failure in brittle materials predominantly results from normal stresses, as evidenced by the rupture created along a surface perpendicular to the applied load. These materials do not display...
4.7K
01:21Fatigue
934
Fatigue occurs when materials rupture under repeated or fluctuating loads, even at stress levels far below their static breaking strength. It typically results in brittle failure, even for ductile materials. It is a critical consideration in designing machines and structural components subjected to repetitive or varying loads. The nature of these loadings can range from fluctuating loads like unbalanced pump impellers causing vibrations to repeatedly bending a thin steel rod wire back and forth...
934
01:15Relation between Poisson's ratio, Modulus of Elasticity and Modulus of Rigidity
661
Deformation occurs in axial and transverse directions when an axial load is applied to a slender bar. This deformation impacts the cubic element within the bar, transforming it into either a rectangular parallelepiped or a rhombus, contingent on its orientation. This transformation process induces shearing strain. Axial loading elicits both shearing and normal strains. Applying an axial load instigates equal normal and shearing stresses on elements oriented at a 45° angle to the load axis.
661
01:25Effects of Creep
514
Creep in concrete, the gradual deformation under prolonged stress, significantly impacts the integrity of structures. For reinforced concrete beams, it can be a vital design consideration, as it increases deflection, sometimes necessitating additional design measures. In columns, especially slender ones under eccentric loads, creep can cause buckling, compromising their stability. However, creep can be beneficial in indeterminate structures by mitigating stresses that arise from shrinkage,...
514
01:20Microcracking in Concrete
524
Microcracking in concrete refers to the tiny cracks that can form within the material even before any external load is applied. These microcracks typically occur at the interface between the coarse aggregate and the hydrated cement paste, often as a result of differential volume changes prompted by variations in stress-strain behavior, as well as thermal and moisture movement. Initially, these microcracks remain stable and do not grow substantially until the concrete is stressed to about 30...
524
01:20Elastic Strain Energy for Shearing Stresses
576
As discussed in previous lessons, strain energy in a material is the energy stored when it is elastically deformed, a concept crucial in materials science and mechanical engineering. This energy results from the internal work done against the cohesive forces within the material. When a material undergoes shearing stress and corresponding shearing strain, the strain energy density, which is the energy stored per unit volume, is calculated. Within the elastic limit, where the stress is...
576