Tangled Dynamic Rupture Propagation on Laboratory Faults
Abstract
We illustrate a series of novel observations obtained in laboratory experiments with a photographic method coupled to acoustic emission monitoring. Two precut samples were put in contact on their edge, under uniaxial load of 1-13 kN, at an angle close to instability in order to ensure the spontaneous triggering of fracture. A high speed digital camera with inter-frame intervals of 10 μsec acquired image sequences of fracture propagation, while a small array of piezo sensors were recording the acoustic emission in the MHz range. The entire process is observed, starting from slow fracture initiation, to acceleration and fully dynamic propagation at sonic and supershear velocity. The silding interface was conditioned in different ways: lubricating patches were added at isolated points and the surface roughness was altered. In the latter case a consistent degree of complexity arises in the rupture, including tangled propagation and re-rupturing within short time intervals. Various radiated waves from the fault rupture are recognized in the photograms and compared to the monitored signal in the piezograms. This allows to evaluate the relative amplitude of the shock wave generated after super-shear transition.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFM.S44A..04N
- Keywords:
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- 7209 Earthquake dynamics (1242);
- 8004 Dynamics and mechanics of faulting (8118);
- 8010 Fractures and faults;
- 8164 Stresses: crust and lithosphere