Related Experiment Video
Updated: May 9, 2026
11:12
Driving Simulation in the Clinic: Testing Visual Exploratory Behavior in Daily Life Activities in Patients with Visual Field Defects
Published on: September 18, 2012
Dislocation damping and anisotropic seismic wave attenuation in Earth's upper mantle
Robert J M Farla1, Ian Jackson, John D Fitz Gerald
1Research School of Earth Sciences, Australian National University, Canberra, Australian Capital Territory 0200, Australia. robert.farla@yale.edu
Science (New York, N.Y.)
|April 21, 2012
Summary
Crystal defects, known as dislocations, may dampen seismic waves. Laboratory experiments show pre-deformed olivine exhibits enhanced wave dissipation, suggesting anisotropic seismic attenuation in Earth's upper mantle.
Area of Science:
- Geophysics
- Solid Earth Geophysics
- Mineral Physics
Background:
- Crystal defects, specifically dislocations, form during tectonic deformation.
- These dislocations may contribute to seismic wave attenuation in the upper mantle.
- Previous laboratory evidence for dislocation damping has been indirect.
Purpose of the Study:
- To experimentally determine shear modulus and strain-energy dissipation in pre-deformed olivine.
- To investigate the role of dislocations in seismic wave attenuation.
- To assess the impact of prior deformation (compression vs. torsion) on dissipation.
Main Methods:
- Experimental determination of shear modulus and strain-energy dissipation.
- Utilizing synthetic olivine aggregates subjected to high pressures and temperatures.
- Employing pre-deformation techniques (compression and torsion) to introduce dislocations.
Main Results:
- Enhanced high-temperature background dissipation observed in pre-deformed olivine.
- Dissipation enhancement was greater in specimens pre-deformed by torsion compared to compression.
- Results indicate a link between dislocation density/type and seismic wave attenuation.
Conclusions:
- Dislocation creep in olivine significantly influences seismic wave dissipation.
- Anisotropic seismic attenuation is possible in the upper mantle due to olivine deformation.
- Findings support the role of crystal defects in modulating seismic wave propagation.
Related Concept Videos
02:30Naturalistic Observations
If you want to understand how behavior occurs, one of the best ways to gain information is to simply observe the behavior in its natural context. However, people might change their behavior in unexpected ways if they know they are being observed. How do researchers obtain accurate information when people tend to hide their natural behavior? As an example, imagine that your professor asks everyone in your class to raise their hand if they always wash their hands after using the restroom. Chances...
01:30Cognitive Development During Adulthood
Cognitive development continues throughout adulthood, undergoing significant shifts across early, middle, and late stages. Individual transition occurs from adolescent idealism to pragmatic and adaptable thinking in early adulthood. During this period, individuals learn to integrate personal beliefs with the recognition that other perspectives are equally valid. Exposure to the complexities of modern society, diverse experiences, and higher education contribute to this adaptive thought process,...