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A supershear transition mechanism for cracks
Eric M Dunham1, Pascal Favreau, J M Carlson
1Department of Physics, University of California, Santa Barbara, CA 93106, USA. edunham@physics.ucsb.edu
Science (New York, N.Y.)
|March 8, 2003
Summary
Stronger fault sections can accelerate ruptures beyond shear wave speed, a phenomenon unique to 3D cracks. This supershear mechanism helps distinguish between barrier and asperity models of fault heterogeneity.
Area of Science:
- Geophysics
- Seismology
- Earthquake rupture dynamics
Background:
- Fault ruptures exhibit complex paths and variable velocities due to heterogeneities in stress and fracture energy.
- Previous models often treated fault heterogeneity as indistinguishable.
Purpose of the Study:
- To investigate the phenomenon of fault ruptures exceeding shear wave speed.
- To differentiate between barrier and asperity models of fault heterogeneity.
Main Methods:
- Analysis of seismic data.
- Modeling of three-dimensional crack behavior.
Main Results:
- Locally stronger fault sections were observed to drive ruptures at velocities exceeding shear wave speed (supershear).
- This supershear mechanism provides a way to distinguish barrier and asperity models.
Conclusions:
- The supershear phenomenon is unique to three-dimensional cracks.
- High-strength barriers concentrate energy, potentially generating destructive ground motion pulses.
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